From e9f0a1af539edfb5dde48a257bc4e81520d80968 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Thu, 28 Jul 2022 09:20:32 -0700
Subject: [PATCH 01/14] WIP

---
 src/compiler/commandLineParser.ts             |  1 +
 src/compiler/moduleNameResolver.ts            | 67 ++++++++++++++++++-
 src/compiler/types.ts                         |  2 +
 src/testRunner/compilerRunner.ts              |  1 +
 .../moduleResolution/minimal_relative.ts      | 47 +++++++++++++
 5 files changed, 117 insertions(+), 1 deletion(-)
 create mode 100644 tests/cases/conformance/moduleResolution/minimal_relative.ts

diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 370461abd8559..646807980fc8f 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -835,6 +835,7 @@ namespace ts {
                 classic: ModuleResolutionKind.Classic,
                 node16: ModuleResolutionKind.Node16,
                 nodenext: ModuleResolutionKind.NodeNext,
+                minimal: ModuleResolutionKind.Minimal,
             })),
             affectsModuleResolution: true,
             paramType: Diagnostics.STRATEGY,
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index 68780ef26aab3..bf8fbb5ca37eb 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -25,6 +25,10 @@ namespace ts {
         return r && { path: r.path, extension: r.ext, packageId };
     }
 
+    function createLoaderWithNoPackageId<P extends any[]>(loader: (...args: P) => PathAndExtension | undefined): (...args: P) => Resolved | undefined {
+        return (...args) => noPackageId(loader(...args));
+    }
+
     function noPackageId(r: PathAndExtension | undefined): Resolved | undefined {
         return withPackageId(/*packageInfo*/ undefined, r);
     }
@@ -1013,6 +1017,9 @@ namespace ts {
                 case ModuleResolutionKind.Classic:
                     result = classicNameResolver(moduleName, containingFile, compilerOptions, host, cache, redirectedReference);
                     break;
+                case ModuleResolutionKind.Minimal:
+                    result = minimalModuleNameResolver(moduleName, containingFile, compilerOptions, host);
+                    break;
                 default:
                     return Debug.fail(`Unexpected moduleResolution: ${moduleResolution}`);
             }
@@ -1550,7 +1557,10 @@ namespace ts {
     function loadModuleFromFileNoImplicitExtensions(extensions: Extensions, candidate: string, onlyRecordFailures: boolean, state: ModuleResolutionState): PathAndExtension | undefined {
         // If that didn't work, try stripping a ".js" or ".jsx" extension and replacing it with a TypeScript one;
         // e.g. "./foo.js" can be matched by "./foo.ts" or "./foo.d.ts"
-        if (hasJSFileExtension(candidate) || (fileExtensionIs(candidate, Extension.Json) && state.compilerOptions.resolveJsonModule)) {
+        if (hasJSFileExtension(candidate) ||
+            (state.compilerOptions.resolveJsonModule && fileExtensionIs(candidate, Extension.Json)) ||
+            (shouldResolveTsExtension(state.compilerOptions) && fileExtensionIsOneOf(candidate, supportedTSExtensionsFlat))
+        ) {
             const extensionless = removeFileExtension(candidate);
             const extension = candidate.substring(extensionless.length);
             if (state.traceEnabled) {
@@ -1610,6 +1620,13 @@ namespace ts {
                     case Extension.Json:
                         candidate += Extension.Json;
                         return useDts ? tryExtension(Extension.Dts) : undefined;
+                    case Extension.Ts:
+                    case Extension.Tsx:
+                    case Extension.Dts:
+                        if (shouldResolveTsExtension(state.compilerOptions)) {
+                            return tryExtension(originalExtension);
+                        }
+                        // falls through
                     default:
                         return tryExtension(Extension.Ts) || tryExtension(Extension.Tsx) || (useDts ? tryExtension(Extension.Dts) : undefined);
                 }
@@ -2636,6 +2653,54 @@ namespace ts {
         }
     }
 
+    export function minimalModuleNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations {
+        const traceEnabled = isTraceEnabled(compilerOptions, host);
+        const failedLookupLocations: string[] = [];
+        const affectingLocations: string[] = [];
+        const containingDirectory = getDirectoryPath(containingFile);
+        const diagnostics: Diagnostic[] = [];
+        const state: ModuleResolutionState = {
+            compilerOptions,
+            host,
+            traceEnabled,
+            failedLookupLocations,
+            affectingLocations,
+            packageJsonInfoCache: undefined,
+            features: NodeResolutionFeatures.None,
+            conditions: [],
+            requestContainingDirectory: containingDirectory,
+            reportDiagnostic: diag => void diagnostics.push(diag),
+        };
+
+        const candidate = normalizePath(combinePaths(containingDirectory, moduleName));
+        return createResolvedModuleWithFailedLookupLocations(
+            tryResolve(Extensions.TypeScript) || tryResolve(Extensions.JavaScript),
+            /*isExternalLibraryImport*/ false,
+            failedLookupLocations,
+            affectingLocations,
+            diagnostics,
+            state.resultFromCache);
+
+        function tryResolve(extensions: Extensions) {
+            const resolvedUsingSettings = tryLoadModuleUsingOptionalResolutionSettings(extensions, moduleName, containingDirectory, createLoaderWithNoPackageId(loadModuleFromFileNoImplicitExtensions), state);
+            if (resolvedUsingSettings) {
+                return resolvedUsingSettings;
+            }
+            const resolvedRelative = loadModuleFromFileNoImplicitExtensions(extensions, candidate, /*onlyRecordFailures*/ false, state);
+            if (resolvedRelative) {
+                return noPackageId(resolvedRelative);
+            }
+        }
+    }
+
+    export function shouldResolveTsExtension(compilerOptions: CompilerOptions) {
+      return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Minimal;
+    }
+
+    export function shouldAllowTsExtension(compilerOptions: CompilerOptions) {
+        return shouldResolveTsExtension(compilerOptions) && !!compilerOptions.noEmit;
+    }
+
     /**
      * A host may load a module from a global cache of typings.
      * This is the minumum code needed to expose that functionality; the rest is in the host.
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index f93f36c369157..d5e5dbbb27ab2 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -6246,6 +6246,8 @@ namespace ts {
         // In turn, we offer both a `NodeNext` moving resolution target, and a `Node16` version-anchored resolution target
         Node16   = 3,
         NodeNext = 99, // Not simply `Node16` so that compiled code linked against TS can use the `Next` value reliably (same as with `ModuleKind`)
+
+        Minimal  = 100,
     }
 
     export enum ModuleDetectionKind {
diff --git a/src/testRunner/compilerRunner.ts b/src/testRunner/compilerRunner.ts
index a6c67a17ee186..2fcda0891a652 100644
--- a/src/testRunner/compilerRunner.ts
+++ b/src/testRunner/compilerRunner.ts
@@ -121,6 +121,7 @@ namespace Harness {
             "moduleDetection",
             "target",
             "jsx",
+            "noEmit",
             "removeComments",
             "importHelpers",
             "importHelpers",
diff --git a/tests/cases/conformance/moduleResolution/minimal_relative.ts b/tests/cases/conformance/moduleResolution/minimal_relative.ts
new file mode 100644
index 0000000000000..48fda19b7c3eb
--- /dev/null
+++ b/tests/cases/conformance/moduleResolution/minimal_relative.ts
@@ -0,0 +1,47 @@
+// @moduleResolution: minimal
+// @outDir: dist
+// @noEmit: true,false
+// @traceResolution: true
+
+// @Filename: /project/a.ts
+export {};
+
+// @Filename: /project/b.ts
+export {};
+
+// @Filename: /project/b.js
+export {};
+
+// @Filename: /project/b.d.ts
+export {};
+
+// @Filename: /project/c.ts
+export {};
+
+// @Filename: /project/c.tsx
+export {};
+
+// @Filename: /project/d/index.ts
+export {};
+
+// @Filename: /project/e
+export {};
+
+// @Filename: /project/main.ts
+import {} from "./a";
+import {} from "./a.js";
+import {} from "./a.ts";
+
+import {} from "./b";
+import {} from "./b.js";
+import {} from "./b.ts";
+import {} from "./b.d.ts";
+
+import {} from "./c.ts";
+import {} from "./c.tsx";
+
+import {} from "./d";
+import {} from "./d/index";
+import {} from "./d/index.ts";
+
+import {} from "./e";

From 5f9cf9db8d71dcc98ffe41b49cde8f181b6beb31 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Fri, 29 Jul 2022 13:07:11 -0700
Subject: [PATCH 02/14] Add extension error back unless noEmit is set

---
 src/compiler/checker.ts                       | 30 +++---
 src/compiler/moduleNameResolver.ts            | 47 ++++++---
 src/compiler/types.ts                         |  5 +
 src/services/shims.ts                         |  2 +-
 src/testRunner/unittests/moduleResolution.ts  |  9 +-
 src/testRunner/unittests/tscWatch/watchApi.ts |  1 +
 .../reference/api/tsserverlibrary.d.ts        | 11 ++-
 tests/baselines/reference/api/typescript.d.ts | 11 ++-
 .../minimal_relative(noemit=false).errors.txt | 95 +++++++++++++++++++
 .../minimal_relative(noemit=false).js         | 58 +++++++++++
 .../minimal_relative(noemit=false).symbols    | 38 ++++++++
 .../minimal_relative(noemit=false).trace.json | 57 +++++++++++
 .../minimal_relative(noemit=false).types      | 38 ++++++++
 .../minimal_relative(noemit=true).errors.txt  | 75 +++++++++++++++
 .../minimal_relative(noemit=true).symbols     | 38 ++++++++
 .../minimal_relative(noemit=true).trace.json  | 57 +++++++++++
 .../minimal_relative(noemit=true).types       | 38 ++++++++
 17 files changed, 582 insertions(+), 28 deletions(-)
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=false).errors.txt
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=false).js
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=false).symbols
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=false).trace.json
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=false).types
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=true).errors.txt
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=true).symbols
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=true).trace.json
 create mode 100644 tests/baselines/reference/minimal_relative(noemit=true).types

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 7768b78ef3ecd..bbcb97e7c881f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3570,6 +3570,10 @@ namespace ts {
                 if (resolutionDiagnostic) {
                     error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName);
                 }
+                if (resolvedModule.resolvedUsingTsExtension && !shouldAllowTsExtension(compilerOptions)) {
+                    const tsExtension = Debug.checkDefined(tryExtractTSExtension(moduleReference));
+                    errorOnTSExtensionImport(tsExtension);
+                }
                 if (sourceFile.symbol) {
                     if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) {
                         errorOnImplicitAnyModule(/*isError*/ false, errorNode, resolvedModule, moduleReference);
@@ -3642,17 +3646,7 @@ namespace ts {
                     const resolutionIsNode16OrNext = moduleResolutionKind === ModuleResolutionKind.Node16 ||
                         moduleResolutionKind === ModuleResolutionKind.NodeNext;
                     if (tsExtension) {
-                        const diag = Diagnostics.An_import_path_cannot_end_with_a_0_extension_Consider_importing_1_instead;
-                        const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension);
-                        let replacedImportSource = importSourceWithoutExtension;
-                        /**
-                         * Direct users to import source with .js extension if outputting an ES module.
-                         * @see https://github.com/microsoft/TypeScript/issues/42151
-                         */
-                        if (moduleKind >= ModuleKind.ES2015) {
-                            replacedImportSource += tsExtension === Extension.Mts ? ".mjs" : tsExtension === Extension.Cts ? ".cjs" : ".js";
-                        }
-                        error(errorNode, diag, tsExtension, replacedImportSource);
+                        errorOnTSExtensionImport(tsExtension);
                     }
                     else if (!compilerOptions.resolveJsonModule &&
                         fileExtensionIs(moduleReference, Extension.Json) &&
@@ -3678,6 +3672,20 @@ namespace ts {
                 }
             }
             return undefined;
+
+            function errorOnTSExtensionImport(tsExtension: string) {
+                const diag = Diagnostics.An_import_path_cannot_end_with_a_0_extension_Consider_importing_1_instead;
+                const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension);
+                let replacedImportSource = importSourceWithoutExtension;
+                /**
+                 * Direct users to import source with .js extension if outputting an ES module.
+                 * @see https://github.com/microsoft/TypeScript/issues/42151
+                 */
+                if (moduleKind >= ModuleKind.ES2015 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Minimal) {
+                    replacedImportSource += tsExtension === Extension.Mts ? ".mjs" : tsExtension === Extension.Cts ? ".cjs" : ".js";
+                }
+                error(errorNode, diag, tsExtension, replacedImportSource);
+            }
         }
 
         function errorOnImplicitAnyModule(isError: boolean, errorNode: Node, { packageId, resolvedFileName }: ResolvedModuleFull, moduleReference: string): void {
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index bf8fbb5ca37eb..5bec091015037 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -22,7 +22,7 @@ namespace ts {
                 };
             }
         }
-        return r && { path: r.path, extension: r.ext, packageId };
+        return r && { path: r.path, extension: r.ext, packageId, resolvedUsingTsExtension: r.resolvedUsingTsExtension };
     }
 
     function createLoaderWithNoPackageId<P extends any[]>(loader: (...args: P) => PathAndExtension | undefined): (...args: P) => Resolved | undefined {
@@ -36,7 +36,7 @@ namespace ts {
     function removeIgnoredPackageId(r: Resolved | undefined): PathAndExtension | undefined {
         if (r) {
             Debug.assert(r.packageId === undefined);
-            return { path: r.path, ext: r.extension };
+            return { path: r.path, ext: r.extension, resolvedUsingTsExtension: r.resolvedUsingTsExtension };
         }
     }
 
@@ -55,6 +55,7 @@ namespace ts {
          * Note: This is a file name with preserved original casing, not a normalized `Path`.
          */
         originalPath?: string | true;
+        resolvedUsingTsExtension: boolean | undefined;
     }
 
     /** Result of trying to resolve a module at a file. Needs to have 'packageId' added later. */
@@ -62,6 +63,7 @@ namespace ts {
         path: string;
         // (Use a different name than `extension` to make sure Resolved isn't assignable to PathAndExtension.)
         ext: Extension;
+        resolvedUsingTsExtension: boolean | undefined;
     }
 
     /**
@@ -104,7 +106,14 @@ namespace ts {
             return resultFromCache;
         }
         return {
-            resolvedModule: resolved && { resolvedFileName: resolved.path, originalPath: resolved.originalPath === true ? undefined : resolved.originalPath, extension: resolved.extension, isExternalLibraryImport, packageId: resolved.packageId },
+            resolvedModule: resolved && {
+                resolvedFileName: resolved.path,
+                originalPath: resolved.originalPath === true ? undefined : resolved.originalPath,
+                extension: resolved.extension,
+                isExternalLibraryImport,
+                packageId: resolved.packageId,
+                resolvedUsingTsExtension: !!resolved.resolvedUsingTsExtension,
+            },
             failedLookupLocations,
             affectingLocations,
             resolutionDiagnostics: diagnostics,
@@ -1573,7 +1582,7 @@ namespace ts {
     function loadJSOrExactTSFileName(extensions: Extensions, candidate: string, onlyRecordFailures: boolean, state: ModuleResolutionState): PathAndExtension | undefined {
         if ((extensions === Extensions.TypeScript || extensions === Extensions.DtsOnly) && fileExtensionIsOneOf(candidate, supportedTSExtensionsFlat)) {
             const result = tryFile(candidate, onlyRecordFailures, state);
-            return result !== undefined ? { path: candidate, ext: tryExtractTSExtension(candidate) as Extension } : undefined;
+            return result !== undefined ? { path: candidate, ext: tryExtractTSExtension(candidate) as Extension, resolvedUsingTsExtension: undefined } : undefined;
         }
 
         return loadModuleFromFileNoImplicitExtensions(extensions, candidate, onlyRecordFailures, state);
@@ -1624,7 +1633,7 @@ namespace ts {
                     case Extension.Tsx:
                     case Extension.Dts:
                         if (shouldResolveTsExtension(state.compilerOptions)) {
-                            return tryExtension(originalExtension);
+                            return tryExtension(originalExtension, /*resolvedUsingTsExtension*/ true);
                         }
                         // falls through
                     default:
@@ -1650,9 +1659,9 @@ namespace ts {
                 return tryExtension(Extension.Json);
         }
 
-        function tryExtension(ext: Extension): PathAndExtension | undefined {
+        function tryExtension(ext: Extension, resolvedUsingTsExtension?: boolean): PathAndExtension | undefined {
             const path = tryFile(candidate + ext, onlyRecordFailures, state);
-            return path === undefined ? undefined : { path, ext };
+            return path === undefined ? undefined : { path, ext, resolvedUsingTsExtension };
         }
     }
 
@@ -1978,9 +1987,9 @@ namespace ts {
     }
 
     /** Resolve from an arbitrarily specified file. Return `undefined` if it has an unsupported extension. */
-    function resolvedIfExtensionMatches(extensions: Extensions, path: string): PathAndExtension | undefined {
+    function resolvedIfExtensionMatches(extensions: Extensions, path: string, resolvedUsingTsExtension?: boolean): PathAndExtension | undefined {
         const ext = tryGetExtensionFromPath(path);
-        return ext !== undefined && extensionIsOk(extensions, ext) ? { path, ext } : undefined;
+        return ext !== undefined && extensionIsOk(extensions, ext) ? { path, ext, resolvedUsingTsExtension } : undefined;
     }
 
     /** True if `extension` is one of the supported `extensions`. */
@@ -2179,7 +2188,13 @@ namespace ts {
                     if (isImports && !startsWith(target, "../") && !startsWith(target, "/") && !isRootedDiskPath(target)) {
                         const combinedLookup = pattern ? target.replace(/\*/g, subpath) : target + subpath;
                         const result = nodeModuleNameResolverWorker(state.features, combinedLookup, scope.packageDirectory + "/", state.compilerOptions, state.host, cache, [extensions], redirectedReference);
-                        return toSearchResult(result.resolvedModule ? { path: result.resolvedModule.resolvedFileName, extension: result.resolvedModule.extension, packageId: result.resolvedModule.packageId, originalPath: result.resolvedModule.originalPath } : undefined);
+                        return toSearchResult(result.resolvedModule ? {
+                            path: result.resolvedModule.resolvedFileName,
+                            extension: result.resolvedModule.extension,
+                            packageId: result.resolvedModule.packageId,
+                            originalPath: result.resolvedModule.originalPath,
+                            resolvedUsingTsExtension: result.resolvedModule.resolvedUsingTsExtension
+                        } : undefined);
                     }
                     if (state.traceEnabled) {
                         trace(state.host, Diagnostics.package_json_scope_0_has_invalid_type_for_target_of_specifier_1, scope.packageDirectory, moduleName);
@@ -2528,7 +2543,7 @@ namespace ts {
                 if (extension !== undefined) {
                     const path = tryFile(candidate, onlyRecordFailures, state);
                     if (path !== undefined) {
-                        return noPackageId({ path, ext: extension });
+                        return noPackageId({ path, ext: extension, resolvedUsingTsExtension: undefined });
                     }
                 }
                 return loader(extensions, candidate, onlyRecordFailures || !directoryProbablyExists(getDirectoryPath(candidate), state.host), state);
@@ -2588,7 +2603,15 @@ namespace ts {
                 trace(state.host, Diagnostics.Resolution_for_module_0_was_found_in_cache_from_location_1, moduleName, containingDirectory);
             }
             state.resultFromCache = result;
-            return { value: result.resolvedModule && { path: result.resolvedModule.resolvedFileName, originalPath: result.resolvedModule.originalPath || true, extension: result.resolvedModule.extension, packageId: result.resolvedModule.packageId } };
+            return {
+                value: result.resolvedModule && {
+                    path: result.resolvedModule.resolvedFileName,
+                    originalPath: result.resolvedModule.originalPath || true,
+                    extension: result.resolvedModule.extension,
+                    packageId: result.resolvedModule.packageId,
+                    resolvedUsingTsExtension: result.resolvedModule.resolvedUsingTsExtension
+                }
+            };
         }
     }
 
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index d5e5dbbb27ab2..4f2c65d876578 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -6853,6 +6853,11 @@ namespace ts {
         resolvedFileName: string;
         /** True if `resolvedFileName` comes from `node_modules`. */
         isExternalLibraryImport?: boolean;
+        /**
+         * True if the original module reference used a .ts extension to refer directly to a .ts file,
+         * which should produce an error during checking if emit is enabled.
+         */
+        resolvedUsingTsExtension: boolean;
     }
 
     /**
diff --git a/src/services/shims.ts b/src/services/shims.ts
index 6d313b695ce67..72b7c936863ea 100644
--- a/src/services/shims.ts
+++ b/src/services/shims.ts
@@ -362,7 +362,7 @@ namespace ts {
                     const resolutionsInFile = JSON.parse(this.shimHost.getModuleResolutionsForFile!(containingFile)) as MapLike<string>; // TODO: GH#18217
                     return map(moduleNames, name => {
                         const result = getProperty(resolutionsInFile, name);
-                        return result ? { resolvedFileName: result, extension: extensionFromPath(result), isExternalLibraryImport: false } : undefined;
+                        return result ? { resolvedFileName: result, extension: extensionFromPath(result), isExternalLibraryImport: false, resolvedUsingTsExtension: false } : undefined;
                     });
                 };
             }
diff --git a/src/testRunner/unittests/moduleResolution.ts b/src/testRunner/unittests/moduleResolution.ts
index 1f85f97827c16..abf0c48773385 100644
--- a/src/testRunner/unittests/moduleResolution.ts
+++ b/src/testRunner/unittests/moduleResolution.ts
@@ -24,8 +24,8 @@ namespace ts {
         assert.deepEqual(actual.failedLookupLocations, expectedFailedLookupLocations, `Failed lookup locations should match - expected has ${expectedFailedLookupLocations.length}, actual has ${actual.failedLookupLocations.length}`);
     }
 
-    export function createResolvedModule(resolvedFileName: string, isExternalLibraryImport = false): ResolvedModuleFull {
-        return { resolvedFileName, extension: extensionFromPath(resolvedFileName), isExternalLibraryImport };
+    export function createResolvedModule(resolvedFileName: string, isExternalLibraryImport = false, resolvedUsingTsExtension = false): ResolvedModuleFull {
+        return { resolvedFileName, extension: extensionFromPath(resolvedFileName), isExternalLibraryImport, resolvedUsingTsExtension };
     }
 
     interface File {
@@ -214,6 +214,7 @@ namespace ts {
                     resolvedFileName: "/sub/node_modules/a/index.ts",
                     isExternalLibraryImport: true,
                     extension: Extension.Ts,
+                    resolvedUsingTsExtension: false,
                 },
                 failedLookupLocations: [],
                 affectingLocations: [],
@@ -229,6 +230,7 @@ namespace ts {
                     resolvedFileName: "/sub/directory/node_modules/b/index.ts",
                     isExternalLibraryImport: true,
                     extension: Extension.Ts,
+                    resolvedUsingTsExtension: false,
                 },
                 failedLookupLocations: [],
                 affectingLocations: [],
@@ -246,6 +248,7 @@ namespace ts {
                     resolvedFileName: "/bar/node_modules/c/index.ts",
                     isExternalLibraryImport: true,
                     extension: Extension.Ts,
+                    resolvedUsingTsExtension: false,
                 },
                 failedLookupLocations: [],
                 affectingLocations: [],
@@ -262,6 +265,7 @@ namespace ts {
                     resolvedFileName: "/foo/index.ts",
                     isExternalLibraryImport: true,
                     extension: Extension.Ts,
+                    resolvedUsingTsExtension: false,
                 },
                 failedLookupLocations: [],
                 affectingLocations: [],
@@ -277,6 +281,7 @@ namespace ts {
                     resolvedFileName: "d:/bar/node_modules/e/index.ts",
                     isExternalLibraryImport: true,
                     extension: Extension.Ts,
+                    resolvedUsingTsExtension: false,
                 },
                 failedLookupLocations: [],
                 affectingLocations: [],
diff --git a/src/testRunner/unittests/tscWatch/watchApi.ts b/src/testRunner/unittests/tscWatch/watchApi.ts
index 477a982eafde2..89b7359309903 100644
--- a/src/testRunner/unittests/tscWatch/watchApi.ts
+++ b/src/testRunner/unittests/tscWatch/watchApi.ts
@@ -35,6 +35,7 @@ namespace ts.tscWatch {
                     resolvedFileName: resolvedModule.resolvedFileName,
                     isExternalLibraryImport: resolvedModule.isExternalLibraryImport,
                     originalFileName: resolvedModule.originalPath,
+                    resolvedUsingTsExtension: false,
                 };
             });
             const watch = createWatchProgram(host);
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index bbc5c38476cdd..1fe485492ffd2 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -2926,7 +2926,8 @@ declare namespace ts {
         Classic = 1,
         NodeJs = 2,
         Node16 = 3,
-        NodeNext = 99
+        NodeNext = 99,
+        Minimal = 100
     }
     export enum ModuleDetectionKind {
         /**
@@ -3221,6 +3222,11 @@ declare namespace ts {
         resolvedFileName: string;
         /** True if `resolvedFileName` comes from `node_modules`. */
         isExternalLibraryImport?: boolean;
+        /**
+         * True if the original module reference used a .ts extension to refer directly to a .ts file,
+         * which should produce an error during checking if emit is enabled.
+         */
+        resolvedUsingTsExtension: boolean;
     }
     /**
      * ResolvedModule with an explicitly provided `extension` property.
@@ -5028,6 +5034,9 @@ declare namespace ts {
     export function resolveModuleName(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: ModuleResolutionCache, redirectedReference?: ResolvedProjectReference, resolutionMode?: ModuleKind.CommonJS | ModuleKind.ESNext): ResolvedModuleWithFailedLookupLocations;
     export function nodeModuleNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: ModuleResolutionCache, redirectedReference?: ResolvedProjectReference): ResolvedModuleWithFailedLookupLocations;
     export function classicNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: NonRelativeModuleNameResolutionCache, redirectedReference?: ResolvedProjectReference): ResolvedModuleWithFailedLookupLocations;
+    export function minimalModuleNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations;
+    export function shouldResolveTsExtension(compilerOptions: CompilerOptions): boolean;
+    export function shouldAllowTsExtension(compilerOptions: CompilerOptions): boolean;
     export {};
 }
 declare namespace ts {
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index f9e5f2d0bdebf..62ea676e7dd8d 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -2926,7 +2926,8 @@ declare namespace ts {
         Classic = 1,
         NodeJs = 2,
         Node16 = 3,
-        NodeNext = 99
+        NodeNext = 99,
+        Minimal = 100
     }
     export enum ModuleDetectionKind {
         /**
@@ -3221,6 +3222,11 @@ declare namespace ts {
         resolvedFileName: string;
         /** True if `resolvedFileName` comes from `node_modules`. */
         isExternalLibraryImport?: boolean;
+        /**
+         * True if the original module reference used a .ts extension to refer directly to a .ts file,
+         * which should produce an error during checking if emit is enabled.
+         */
+        resolvedUsingTsExtension: boolean;
     }
     /**
      * ResolvedModule with an explicitly provided `extension` property.
@@ -5028,6 +5034,9 @@ declare namespace ts {
     export function resolveModuleName(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: ModuleResolutionCache, redirectedReference?: ResolvedProjectReference, resolutionMode?: ModuleKind.CommonJS | ModuleKind.ESNext): ResolvedModuleWithFailedLookupLocations;
     export function nodeModuleNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: ModuleResolutionCache, redirectedReference?: ResolvedProjectReference): ResolvedModuleWithFailedLookupLocations;
     export function classicNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: NonRelativeModuleNameResolutionCache, redirectedReference?: ResolvedProjectReference): ResolvedModuleWithFailedLookupLocations;
+    export function minimalModuleNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations;
+    export function shouldResolveTsExtension(compilerOptions: CompilerOptions): boolean;
+    export function shouldAllowTsExtension(compilerOptions: CompilerOptions): boolean;
     export {};
 }
 declare namespace ts {
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).errors.txt b/tests/baselines/reference/minimal_relative(noemit=false).errors.txt
new file mode 100644
index 0000000000000..fde1ffef20104
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=false).errors.txt
@@ -0,0 +1,95 @@
+error TS5056: Cannot write file 'dist/c.js' because it would be overwritten by multiple input files.
+error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+  The file is in the program because:
+    Root file specified for compilation
+error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+  The file is in the program because:
+    Root file specified for compilation
+/project/main.ts(1,16): error TS2307: Cannot find module './a' or its corresponding type declarations.
+/project/main.ts(3,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './a.js' instead.
+/project/main.ts(5,16): error TS2307: Cannot find module './b' or its corresponding type declarations.
+/project/main.ts(7,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './b.js' instead.
+/project/main.ts(8,16): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './b.js' instead.
+/project/main.ts(10,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './c.js' instead.
+/project/main.ts(11,16): error TS2691: An import path cannot end with a '.tsx' extension. Consider importing './c.js' instead.
+/project/main.ts(11,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+/project/main.ts(13,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
+/project/main.ts(14,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+/project/main.ts(15,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './d/index.js' instead.
+/project/main.ts(17,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
+
+
+!!! error TS5056: Cannot write file 'dist/c.js' because it would be overwritten by multiple input files.
+!!! error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+!!! error TS6231:   The file is in the program because:
+!!! error TS6231:     Root file specified for compilation
+!!! error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+!!! error TS6504:   The file is in the program because:
+!!! error TS6504:     Root file specified for compilation
+==== /project/a.ts (0 errors) ====
+    export {};
+    
+==== /project/b.ts (0 errors) ====
+    export {};
+    
+==== /project/b.js (0 errors) ====
+    export {};
+    
+==== /project/b.d.ts (0 errors) ====
+    export {};
+    
+==== /project/c.ts (0 errors) ====
+    export {};
+    
+==== /project/c.tsx (0 errors) ====
+    export {};
+    
+==== /project/d/index.ts (0 errors) ====
+    export {};
+    
+==== /project/e (0 errors) ====
+    export {};
+    
+==== /project/main.ts (12 errors) ====
+    import {} from "./a";
+                   ~~~~~
+!!! error TS2307: Cannot find module './a' or its corresponding type declarations.
+    import {} from "./a.js";
+    import {} from "./a.ts";
+                   ~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.ts' extension. Consider importing './a.js' instead.
+    
+    import {} from "./b";
+                   ~~~~~
+!!! error TS2307: Cannot find module './b' or its corresponding type declarations.
+    import {} from "./b.js";
+    import {} from "./b.ts";
+                   ~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.ts' extension. Consider importing './b.js' instead.
+    import {} from "./b.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './b.js' instead.
+    
+    import {} from "./c.ts";
+                   ~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.ts' extension. Consider importing './c.js' instead.
+    import {} from "./c.tsx";
+                   ~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.tsx' extension. Consider importing './c.js' instead.
+                   ~~~~~~~~~
+!!! error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+    
+    import {} from "./d";
+                   ~~~~~
+!!! error TS2307: Cannot find module './d' or its corresponding type declarations.
+    import {} from "./d/index";
+                   ~~~~~~~~~~~
+!!! error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+    import {} from "./d/index.ts";
+                   ~~~~~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.ts' extension. Consider importing './d/index.js' instead.
+    
+    import {} from "./e";
+                   ~~~~~
+!!! error TS2307: Cannot find module './e' or its corresponding type declarations.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).js b/tests/baselines/reference/minimal_relative(noemit=false).js
new file mode 100644
index 0000000000000..ca36c746501fb
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=false).js
@@ -0,0 +1,58 @@
+//// [tests/cases/conformance/moduleResolution/minimal_relative.ts] ////
+
+//// [a.ts]
+export {};
+
+//// [b.ts]
+export {};
+
+//// [b.js]
+export {};
+
+//// [b.d.ts]
+export {};
+
+//// [c.ts]
+export {};
+
+//// [c.tsx]
+export {};
+
+//// [index.ts]
+export {};
+
+//// [e]
+export {};
+
+//// [main.ts]
+import {} from "./a";
+import {} from "./a.js";
+import {} from "./a.ts";
+
+import {} from "./b";
+import {} from "./b.js";
+import {} from "./b.ts";
+import {} from "./b.d.ts";
+
+import {} from "./c.ts";
+import {} from "./c.tsx";
+
+import {} from "./d";
+import {} from "./d/index";
+import {} from "./d/index.ts";
+
+import {} from "./e";
+
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+//// [b.js]
+"use strict";
+exports.__esModule = true;
+//// [index.js]
+"use strict";
+exports.__esModule = true;
+//// [main.js]
+"use strict";
+exports.__esModule = true;
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).symbols b/tests/baselines/reference/minimal_relative(noemit=false).symbols
new file mode 100644
index 0000000000000..42b5e186aa78d
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=false).symbols
@@ -0,0 +1,38 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).trace.json b/tests/baselines/reference/minimal_relative(noemit=false).trace.json
new file mode 100644
index 0000000000000..33784890cf65f
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=false).trace.json
@@ -0,0 +1,57 @@
+[
+    "======== Resolving module './a' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './a' was not resolved. ========",
+    "======== Resolving module './a.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.js' has a '.js' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.js' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.ts' has a '.ts' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './b' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './b' was not resolved. ========",
+    "======== Resolving module './b.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.js' has a '.js' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.js' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.ts' has a '.ts' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.ts' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.d.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/b.d.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.d.ts' was successfully resolved to '/project/b.d.ts'. ========",
+    "======== Resolving module './c.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.ts' has a '.ts' extension - stripping it.",
+    "File '/project/c.ts' exist - use it as a name resolution result.",
+    "======== Module name './c.ts' was successfully resolved to '/project/c.ts'. ========",
+    "======== Resolving module './c.tsx' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.tsx' has a '.tsx' extension - stripping it.",
+    "File '/project/c.tsx' exist - use it as a name resolution result.",
+    "======== Module name './c.tsx' was successfully resolved to '/project/c.tsx'. ========",
+    "======== Resolving module './d' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d' was not resolved. ========",
+    "======== Resolving module './d/index' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d/index' was not resolved. ========",
+    "======== Resolving module './d/index.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/d/index.ts' has a '.ts' extension - stripping it.",
+    "File '/project/d/index.ts' exist - use it as a name resolution result.",
+    "======== Module name './d/index.ts' was successfully resolved to '/project/d/index.ts'. ========",
+    "======== Resolving module './e' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './e' was not resolved. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).types b/tests/baselines/reference/minimal_relative(noemit=false).types
new file mode 100644
index 0000000000000..42b5e186aa78d
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=false).types
@@ -0,0 +1,38 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(noemit=true).errors.txt b/tests/baselines/reference/minimal_relative(noemit=true).errors.txt
new file mode 100644
index 0000000000000..7c405129a243d
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=true).errors.txt
@@ -0,0 +1,75 @@
+error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+  The file is in the program because:
+    Root file specified for compilation
+error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+  The file is in the program because:
+    Root file specified for compilation
+/project/main.ts(1,16): error TS2307: Cannot find module './a' or its corresponding type declarations.
+/project/main.ts(5,16): error TS2307: Cannot find module './b' or its corresponding type declarations.
+/project/main.ts(11,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+/project/main.ts(13,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
+/project/main.ts(14,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+/project/main.ts(17,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
+
+
+!!! error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+!!! error TS6231:   The file is in the program because:
+!!! error TS6231:     Root file specified for compilation
+!!! error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+!!! error TS6504:   The file is in the program because:
+!!! error TS6504:     Root file specified for compilation
+==== /project/a.ts (0 errors) ====
+    export {};
+    
+==== /project/b.ts (0 errors) ====
+    export {};
+    
+==== /project/b.js (0 errors) ====
+    export {};
+    
+==== /project/b.d.ts (0 errors) ====
+    export {};
+    
+==== /project/c.ts (0 errors) ====
+    export {};
+    
+==== /project/c.tsx (0 errors) ====
+    export {};
+    
+==== /project/d/index.ts (0 errors) ====
+    export {};
+    
+==== /project/e (0 errors) ====
+    export {};
+    
+==== /project/main.ts (6 errors) ====
+    import {} from "./a";
+                   ~~~~~
+!!! error TS2307: Cannot find module './a' or its corresponding type declarations.
+    import {} from "./a.js";
+    import {} from "./a.ts";
+    
+    import {} from "./b";
+                   ~~~~~
+!!! error TS2307: Cannot find module './b' or its corresponding type declarations.
+    import {} from "./b.js";
+    import {} from "./b.ts";
+    import {} from "./b.d.ts";
+    
+    import {} from "./c.ts";
+    import {} from "./c.tsx";
+                   ~~~~~~~~~
+!!! error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+    
+    import {} from "./d";
+                   ~~~~~
+!!! error TS2307: Cannot find module './d' or its corresponding type declarations.
+    import {} from "./d/index";
+                   ~~~~~~~~~~~
+!!! error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+    import {} from "./d/index.ts";
+    
+    import {} from "./e";
+                   ~~~~~
+!!! error TS2307: Cannot find module './e' or its corresponding type declarations.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(noemit=true).symbols b/tests/baselines/reference/minimal_relative(noemit=true).symbols
new file mode 100644
index 0000000000000..42b5e186aa78d
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=true).symbols
@@ -0,0 +1,38 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(noemit=true).trace.json b/tests/baselines/reference/minimal_relative(noemit=true).trace.json
new file mode 100644
index 0000000000000..33784890cf65f
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=true).trace.json
@@ -0,0 +1,57 @@
+[
+    "======== Resolving module './a' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './a' was not resolved. ========",
+    "======== Resolving module './a.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.js' has a '.js' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.js' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.ts' has a '.ts' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './b' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './b' was not resolved. ========",
+    "======== Resolving module './b.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.js' has a '.js' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.js' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.ts' has a '.ts' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.ts' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.d.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/b.d.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.d.ts' was successfully resolved to '/project/b.d.ts'. ========",
+    "======== Resolving module './c.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.ts' has a '.ts' extension - stripping it.",
+    "File '/project/c.ts' exist - use it as a name resolution result.",
+    "======== Module name './c.ts' was successfully resolved to '/project/c.ts'. ========",
+    "======== Resolving module './c.tsx' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.tsx' has a '.tsx' extension - stripping it.",
+    "File '/project/c.tsx' exist - use it as a name resolution result.",
+    "======== Module name './c.tsx' was successfully resolved to '/project/c.tsx'. ========",
+    "======== Resolving module './d' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d' was not resolved. ========",
+    "======== Resolving module './d/index' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d/index' was not resolved. ========",
+    "======== Resolving module './d/index.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/d/index.ts' has a '.ts' extension - stripping it.",
+    "File '/project/d/index.ts' exist - use it as a name resolution result.",
+    "======== Module name './d/index.ts' was successfully resolved to '/project/d/index.ts'. ========",
+    "======== Resolving module './e' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './e' was not resolved. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(noemit=true).types b/tests/baselines/reference/minimal_relative(noemit=true).types
new file mode 100644
index 0000000000000..42b5e186aa78d
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(noemit=true).types
@@ -0,0 +1,38 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.
\ No newline at end of file

From 2421cf58ab4527288c26668e0e1e39e19a598dfe Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Fri, 29 Jul 2022 13:46:17 -0700
Subject: [PATCH 03/14] Add non-relative tests

---
 .../reference/minimal_nonRelative.errors.txt  | 18 +++++
 .../reference/minimal_nonRelative.trace.json  | 14 ++++
 .../minimal_pathsAndBaseUrl.errors.txt        | 38 ++++++++++
 .../minimal_pathsAndBaseUrl.trace.json        | 73 +++++++++++++++++++
 .../moduleResolution/minimal_nonRelative.ts   | 14 ++++
 .../minimal_pathsAndBaseUrl.ts                | 35 +++++++++
 6 files changed, 192 insertions(+)
 create mode 100644 tests/baselines/reference/minimal_nonRelative.errors.txt
 create mode 100644 tests/baselines/reference/minimal_nonRelative.trace.json
 create mode 100644 tests/baselines/reference/minimal_pathsAndBaseUrl.errors.txt
 create mode 100644 tests/baselines/reference/minimal_pathsAndBaseUrl.trace.json
 create mode 100644 tests/cases/conformance/moduleResolution/minimal_nonRelative.ts
 create mode 100644 tests/cases/conformance/moduleResolution/minimal_pathsAndBaseUrl.ts

diff --git a/tests/baselines/reference/minimal_nonRelative.errors.txt b/tests/baselines/reference/minimal_nonRelative.errors.txt
new file mode 100644
index 0000000000000..9229d86fe597c
--- /dev/null
+++ b/tests/baselines/reference/minimal_nonRelative.errors.txt
@@ -0,0 +1,18 @@
+/main.ts(1,16): error TS2307: Cannot find module 'foo' or its corresponding type declarations.
+/main.ts(2,16): error TS2307: Cannot find module 'bar' or its corresponding type declarations.
+
+
+==== /node_modules/@types/foo/index.d.ts (0 errors) ====
+    export {};
+    
+==== /node_modules/bar/index.d.ts (0 errors) ====
+    export {};
+    
+==== /main.ts (2 errors) ====
+    import {} from "foo";
+                   ~~~~~
+!!! error TS2307: Cannot find module 'foo' or its corresponding type declarations.
+    import {} from "bar";
+                   ~~~~~
+!!! error TS2307: Cannot find module 'bar' or its corresponding type declarations.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_nonRelative.trace.json b/tests/baselines/reference/minimal_nonRelative.trace.json
new file mode 100644
index 0000000000000..769cebfe4261f
--- /dev/null
+++ b/tests/baselines/reference/minimal_nonRelative.trace.json
@@ -0,0 +1,14 @@
+[
+    "======== Resolving module 'foo' from '/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name 'foo' was not resolved. ========",
+    "======== Resolving module 'bar' from '/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name 'bar' was not resolved. ========",
+    "======== Resolving type reference directive 'foo', containing file '__inferred type names__.ts', root directory '/node_modules/@types'. ========",
+    "Resolving with primary search path '/node_modules/@types'.",
+    "File '/node_modules/@types/foo/package.json' does not exist.",
+    "File '/node_modules/@types/foo/index.d.ts' exist - use it as a name resolution result.",
+    "Resolving real path for '/node_modules/@types/foo/index.d.ts', result '/node_modules/@types/foo/index.d.ts'.",
+    "======== Type reference directive 'foo' was successfully resolved to '/node_modules/@types/foo/index.d.ts', primary: true. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_pathsAndBaseUrl.errors.txt b/tests/baselines/reference/minimal_pathsAndBaseUrl.errors.txt
new file mode 100644
index 0000000000000..a1b7074087d13
--- /dev/null
+++ b/tests/baselines/reference/minimal_pathsAndBaseUrl.errors.txt
@@ -0,0 +1,38 @@
+/main.ts(4,16): error TS2307: Cannot find module 'hello' or its corresponding type declarations.
+
+
+==== /tsconfig.json (0 errors) ====
+    {
+      "compilerOptions": {
+        "moduleResolution": "minimal",
+        "noEmit": true,
+        "baseUrl": ".",
+        "paths": {
+          "*": [
+            "*",
+            "./vendor/*",
+            "./vendor/*/index.d.ts",
+            "./apps/*"
+          ]
+        }
+      }
+    }
+    
+==== /vendor/foo/index.d.ts (0 errors) ====
+    export {};
+    
+==== /apps/hello.ts (0 errors) ====
+    export {};
+    
+==== /foo.ts (0 errors) ====
+    export {};
+    
+==== /main.ts (1 errors) ====
+    import {} from "foo";
+    import {} from "foo/index.js";
+    import {} from "hello.ts";
+    import {} from "hello";
+                   ~~~~~~~
+!!! error TS2307: Cannot find module 'hello' or its corresponding type declarations.
+    import {} from "foo.js";
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_pathsAndBaseUrl.trace.json b/tests/baselines/reference/minimal_pathsAndBaseUrl.trace.json
new file mode 100644
index 0000000000000..9d8aa1165d31a
--- /dev/null
+++ b/tests/baselines/reference/minimal_pathsAndBaseUrl.trace.json
@@ -0,0 +1,73 @@
+[
+    "======== Resolving module 'foo' from '/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "'baseUrl' option is set to '/', using this value to resolve non-relative module name 'foo'.",
+    "'paths' option is specified, looking for a pattern to match module name 'foo'.",
+    "Module name 'foo', matched pattern '*'.",
+    "Trying substitution '*', candidate module location: 'foo'.",
+    "Trying substitution './vendor/*', candidate module location: './vendor/foo'.",
+    "Trying substitution './vendor/*/index.d.ts', candidate module location: './vendor/foo/index.d.ts'.",
+    "File '/vendor/foo/index.d.ts' exist - use it as a name resolution result.",
+    "======== Module name 'foo' was successfully resolved to '/vendor/foo/index.d.ts'. ========",
+    "======== Resolving module 'foo/index.js' from '/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "'baseUrl' option is set to '/', using this value to resolve non-relative module name 'foo/index.js'.",
+    "'paths' option is specified, looking for a pattern to match module name 'foo/index.js'.",
+    "Module name 'foo/index.js', matched pattern '*'.",
+    "Trying substitution '*', candidate module location: 'foo/index.js'.",
+    "File name '/foo/index.js' has a '.js' extension - stripping it.",
+    "Trying substitution './vendor/*', candidate module location: './vendor/foo/index.js'.",
+    "File name '/vendor/foo/index.js' has a '.js' extension - stripping it.",
+    "File '/vendor/foo/index.ts' does not exist.",
+    "File '/vendor/foo/index.tsx' does not exist.",
+    "File '/vendor/foo/index.d.ts' exist - use it as a name resolution result.",
+    "======== Module name 'foo/index.js' was successfully resolved to '/vendor/foo/index.d.ts'. ========",
+    "======== Resolving module 'hello.ts' from '/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "'baseUrl' option is set to '/', using this value to resolve non-relative module name 'hello.ts'.",
+    "'paths' option is specified, looking for a pattern to match module name 'hello.ts'.",
+    "Module name 'hello.ts', matched pattern '*'.",
+    "Trying substitution '*', candidate module location: 'hello.ts'.",
+    "File name '/hello.ts' has a '.ts' extension - stripping it.",
+    "File '/hello.ts' does not exist.",
+    "Trying substitution './vendor/*', candidate module location: './vendor/hello.ts'.",
+    "File name '/vendor/hello.ts' has a '.ts' extension - stripping it.",
+    "File '/vendor/hello.ts' does not exist.",
+    "Trying substitution './vendor/*/index.d.ts', candidate module location: './vendor/hello.ts/index.d.ts'.",
+    "File '/vendor/hello.ts/index.d.ts' does not exist.",
+    "File name '/vendor/hello.ts/index.d.ts' has a '.d.ts' extension - stripping it.",
+    "Trying substitution './apps/*', candidate module location: './apps/hello.ts'.",
+    "File name '/apps/hello.ts' has a '.ts' extension - stripping it.",
+    "File '/apps/hello.ts' exist - use it as a name resolution result.",
+    "======== Module name 'hello.ts' was successfully resolved to '/apps/hello.ts'. ========",
+    "======== Resolving module 'hello' from '/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "'baseUrl' option is set to '/', using this value to resolve non-relative module name 'hello'.",
+    "'paths' option is specified, looking for a pattern to match module name 'hello'.",
+    "Module name 'hello', matched pattern '*'.",
+    "Trying substitution '*', candidate module location: 'hello'.",
+    "Trying substitution './vendor/*', candidate module location: './vendor/hello'.",
+    "Trying substitution './vendor/*/index.d.ts', candidate module location: './vendor/hello/index.d.ts'.",
+    "File '/vendor/hello/index.d.ts' does not exist.",
+    "File name '/vendor/hello/index.d.ts' has a '.d.ts' extension - stripping it.",
+    "Trying substitution './apps/*', candidate module location: './apps/hello'.",
+    "'baseUrl' option is set to '/', using this value to resolve non-relative module name 'hello'.",
+    "'paths' option is specified, looking for a pattern to match module name 'hello'.",
+    "Module name 'hello', matched pattern '*'.",
+    "Trying substitution '*', candidate module location: 'hello'.",
+    "Trying substitution './vendor/*', candidate module location: './vendor/hello'.",
+    "Trying substitution './vendor/*/index.d.ts', candidate module location: './vendor/hello/index.d.ts'.",
+    "File '/vendor/hello/index.d.ts' does not exist.",
+    "File name '/vendor/hello/index.d.ts' has a '.d.ts' extension - stripping it.",
+    "Trying substitution './apps/*', candidate module location: './apps/hello'.",
+    "======== Module name 'hello' was not resolved. ========",
+    "======== Resolving module 'foo.js' from '/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "'baseUrl' option is set to '/', using this value to resolve non-relative module name 'foo.js'.",
+    "'paths' option is specified, looking for a pattern to match module name 'foo.js'.",
+    "Module name 'foo.js', matched pattern '*'.",
+    "Trying substitution '*', candidate module location: 'foo.js'.",
+    "File name '/foo.js' has a '.js' extension - stripping it.",
+    "File '/foo.ts' exist - use it as a name resolution result.",
+    "======== Module name 'foo.js' was successfully resolved to '/foo.ts'. ========"
+]
\ No newline at end of file
diff --git a/tests/cases/conformance/moduleResolution/minimal_nonRelative.ts b/tests/cases/conformance/moduleResolution/minimal_nonRelative.ts
new file mode 100644
index 0000000000000..e055574fc2739
--- /dev/null
+++ b/tests/cases/conformance/moduleResolution/minimal_nonRelative.ts
@@ -0,0 +1,14 @@
+// @moduleResolution: minimal
+// @noEmit: true
+// @traceResolution: true
+// @noTypesAndSymbols: true
+
+// @Filename: /node_modules/@types/foo/index.d.ts
+export {};
+
+// @Filename: /node_modules/bar/index.d.ts
+export {};
+
+// @Filename: /main.ts
+import {} from "foo";
+import {} from "bar";
diff --git a/tests/cases/conformance/moduleResolution/minimal_pathsAndBaseUrl.ts b/tests/cases/conformance/moduleResolution/minimal_pathsAndBaseUrl.ts
new file mode 100644
index 0000000000000..a7fb1a2c4ebb6
--- /dev/null
+++ b/tests/cases/conformance/moduleResolution/minimal_pathsAndBaseUrl.ts
@@ -0,0 +1,35 @@
+// @traceResolution: true
+// @noTypesAndSymbols: true
+
+// @Filename: /tsconfig.json
+{
+  "compilerOptions": {
+    "moduleResolution": "minimal",
+    "noEmit": true,
+    "baseUrl": ".",
+    "paths": {
+      "*": [
+        "*",
+        "./vendor/*",
+        "./vendor/*/index.d.ts",
+        "./apps/*"
+      ]
+    }
+  }
+}
+
+// @Filename: /vendor/foo/index.d.ts
+export {};
+
+// @Filename: /apps/hello.ts
+export {};
+
+// @Filename: /foo.ts
+export {};
+
+// @Filename: /main.ts
+import {} from "foo";
+import {} from "foo/index.js";
+import {} from "hello.ts";
+import {} from "hello";
+import {} from "foo.js";

From 660026e966000df368516a156f53e3652f913ef2 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Fri, 29 Jul 2022 15:02:41 -0700
Subject: [PATCH 04/14] Add error for importing from declaration file

---
 src/compiler/checker.ts                       | 24 +++++++++++++++----
 src/compiler/diagnosticMessages.json          |  4 ++++
 .../minimal_relative(noemit=false).errors.txt | 19 ++++++++-------
 .../minimal_relative(noemit=false).js         |  1 +
 .../minimal_relative(noemit=false).symbols    |  1 +
 .../minimal_relative(noemit=false).types      |  1 +
 .../minimal_relative(noemit=true).errors.txt  | 14 +++++++----
 .../minimal_relative(noemit=true).symbols     |  1 +
 .../minimal_relative(noemit=true).types       |  1 +
 .../moduleResolution/minimal_relative.ts      |  1 +
 10 files changed, 49 insertions(+), 18 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index bbcb97e7c881f..eb5d398dc4c35 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3570,10 +3570,23 @@ namespace ts {
                 if (resolutionDiagnostic) {
                     error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName);
                 }
-                if (resolvedModule.resolvedUsingTsExtension && !shouldAllowTsExtension(compilerOptions)) {
+
+                if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) {
+                    const importOrExport =
+                        findAncestor(location, isImportDeclaration)?.importClause ||
+                        findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)) as ImportEqualsDeclaration | ExportDeclaration | undefined;
+                    if (importOrExport && !importOrExport.isTypeOnly || findAncestor(location, isImportCall)) {
+                        error(
+                            errorNode,
+                            Diagnostics.A_declaration_file_cannot_be_imported_without_import_type_Did_you_mean_to_import_an_implementation_file_0_instead,
+                            getSuggestedImportSource(Debug.checkDefined(tryExtractTSExtension(moduleReference))));
+                    }
+                }
+                else if (resolvedModule.resolvedUsingTsExtension && !shouldAllowTsExtension(compilerOptions)) {
                     const tsExtension = Debug.checkDefined(tryExtractTSExtension(moduleReference));
                     errorOnTSExtensionImport(tsExtension);
                 }
+
                 if (sourceFile.symbol) {
                     if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) {
                         errorOnImplicitAnyModule(/*isError*/ false, errorNode, resolvedModule, moduleReference);
@@ -3675,16 +3688,19 @@ namespace ts {
 
             function errorOnTSExtensionImport(tsExtension: string) {
                 const diag = Diagnostics.An_import_path_cannot_end_with_a_0_extension_Consider_importing_1_instead;
+                error(errorNode, diag, tsExtension, getSuggestedImportSource(tsExtension));
+            }
+
+            function getSuggestedImportSource(tsExtension: string) {
                 const importSourceWithoutExtension = removeExtension(moduleReference, tsExtension);
-                let replacedImportSource = importSourceWithoutExtension;
                 /**
                  * Direct users to import source with .js extension if outputting an ES module.
                  * @see https://github.com/microsoft/TypeScript/issues/42151
                  */
                 if (moduleKind >= ModuleKind.ES2015 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Minimal) {
-                    replacedImportSource += tsExtension === Extension.Mts ? ".mjs" : tsExtension === Extension.Cts ? ".cjs" : ".js";
+                    return importSourceWithoutExtension + (tsExtension === Extension.Mts ? ".mjs" : tsExtension === Extension.Cts ? ".cjs" : ".js");
                 }
-                error(errorNode, diag, tsExtension, replacedImportSource);
+                return importSourceWithoutExtension;
             }
         }
 
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index dc22ff2b4b7e3..718d8845e85bc 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -3515,6 +3515,10 @@
         "category": "Error",
         "code": 2844
     },
+    "A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file '{0}' instead?": {
+        "category": "Error",
+        "code": 2845
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).errors.txt b/tests/baselines/reference/minimal_relative(noemit=false).errors.txt
index fde1ffef20104..04640dbdd2934 100644
--- a/tests/baselines/reference/minimal_relative(noemit=false).errors.txt
+++ b/tests/baselines/reference/minimal_relative(noemit=false).errors.txt
@@ -9,14 +9,14 @@ error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable
 /project/main.ts(3,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './a.js' instead.
 /project/main.ts(5,16): error TS2307: Cannot find module './b' or its corresponding type declarations.
 /project/main.ts(7,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './b.js' instead.
-/project/main.ts(8,16): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './b.js' instead.
-/project/main.ts(10,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './c.js' instead.
-/project/main.ts(11,16): error TS2691: An import path cannot end with a '.tsx' extension. Consider importing './c.js' instead.
-/project/main.ts(11,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
-/project/main.ts(13,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
-/project/main.ts(14,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
-/project/main.ts(15,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './d/index.js' instead.
-/project/main.ts(17,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
+/project/main.ts(8,16): error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+/project/main.ts(11,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './c.js' instead.
+/project/main.ts(12,16): error TS2691: An import path cannot end with a '.tsx' extension. Consider importing './c.js' instead.
+/project/main.ts(12,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+/project/main.ts(14,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
+/project/main.ts(15,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+/project/main.ts(16,16): error TS2691: An import path cannot end with a '.ts' extension. Consider importing './d/index.js' instead.
+/project/main.ts(18,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
 
 
 !!! error TS5056: Cannot write file 'dist/c.js' because it would be overwritten by multiple input files.
@@ -68,7 +68,8 @@ error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable
 !!! error TS2691: An import path cannot end with a '.ts' extension. Consider importing './b.js' instead.
     import {} from "./b.d.ts";
                    ~~~~~~~~~~
-!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './b.js' instead.
+!!! error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+    import type {} from "./b.d.ts";
     
     import {} from "./c.ts";
                    ~~~~~~~~
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).js b/tests/baselines/reference/minimal_relative(noemit=false).js
index ca36c746501fb..4044dbad4adb8 100644
--- a/tests/baselines/reference/minimal_relative(noemit=false).js
+++ b/tests/baselines/reference/minimal_relative(noemit=false).js
@@ -33,6 +33,7 @@ import {} from "./b";
 import {} from "./b.js";
 import {} from "./b.ts";
 import {} from "./b.d.ts";
+import type {} from "./b.d.ts";
 
 import {} from "./c.ts";
 import {} from "./c.tsx";
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).symbols b/tests/baselines/reference/minimal_relative(noemit=false).symbols
index 42b5e186aa78d..13a097c71c1b7 100644
--- a/tests/baselines/reference/minimal_relative(noemit=false).symbols
+++ b/tests/baselines/reference/minimal_relative(noemit=false).symbols
@@ -25,6 +25,7 @@ No type information for this code.import {} from "./b";
 No type information for this code.import {} from "./b.js";
 No type information for this code.import {} from "./b.ts";
 No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
 No type information for this code.
 No type information for this code.import {} from "./c.ts";
 No type information for this code.import {} from "./c.tsx";
diff --git a/tests/baselines/reference/minimal_relative(noemit=false).types b/tests/baselines/reference/minimal_relative(noemit=false).types
index 42b5e186aa78d..13a097c71c1b7 100644
--- a/tests/baselines/reference/minimal_relative(noemit=false).types
+++ b/tests/baselines/reference/minimal_relative(noemit=false).types
@@ -25,6 +25,7 @@ No type information for this code.import {} from "./b";
 No type information for this code.import {} from "./b.js";
 No type information for this code.import {} from "./b.ts";
 No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
 No type information for this code.
 No type information for this code.import {} from "./c.ts";
 No type information for this code.import {} from "./c.tsx";
diff --git a/tests/baselines/reference/minimal_relative(noemit=true).errors.txt b/tests/baselines/reference/minimal_relative(noemit=true).errors.txt
index 7c405129a243d..b5584db1abe5f 100644
--- a/tests/baselines/reference/minimal_relative(noemit=true).errors.txt
+++ b/tests/baselines/reference/minimal_relative(noemit=true).errors.txt
@@ -6,10 +6,11 @@ error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable
     Root file specified for compilation
 /project/main.ts(1,16): error TS2307: Cannot find module './a' or its corresponding type declarations.
 /project/main.ts(5,16): error TS2307: Cannot find module './b' or its corresponding type declarations.
-/project/main.ts(11,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
-/project/main.ts(13,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
-/project/main.ts(14,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
-/project/main.ts(17,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
+/project/main.ts(8,16): error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+/project/main.ts(12,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+/project/main.ts(14,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
+/project/main.ts(15,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+/project/main.ts(18,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
 
 
 !!! error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
@@ -42,7 +43,7 @@ error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable
 ==== /project/e (0 errors) ====
     export {};
     
-==== /project/main.ts (6 errors) ====
+==== /project/main.ts (7 errors) ====
     import {} from "./a";
                    ~~~~~
 !!! error TS2307: Cannot find module './a' or its corresponding type declarations.
@@ -55,6 +56,9 @@ error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable
     import {} from "./b.js";
     import {} from "./b.ts";
     import {} from "./b.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+    import type {} from "./b.d.ts";
     
     import {} from "./c.ts";
     import {} from "./c.tsx";
diff --git a/tests/baselines/reference/minimal_relative(noemit=true).symbols b/tests/baselines/reference/minimal_relative(noemit=true).symbols
index 42b5e186aa78d..13a097c71c1b7 100644
--- a/tests/baselines/reference/minimal_relative(noemit=true).symbols
+++ b/tests/baselines/reference/minimal_relative(noemit=true).symbols
@@ -25,6 +25,7 @@ No type information for this code.import {} from "./b";
 No type information for this code.import {} from "./b.js";
 No type information for this code.import {} from "./b.ts";
 No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
 No type information for this code.
 No type information for this code.import {} from "./c.ts";
 No type information for this code.import {} from "./c.tsx";
diff --git a/tests/baselines/reference/minimal_relative(noemit=true).types b/tests/baselines/reference/minimal_relative(noemit=true).types
index 42b5e186aa78d..13a097c71c1b7 100644
--- a/tests/baselines/reference/minimal_relative(noemit=true).types
+++ b/tests/baselines/reference/minimal_relative(noemit=true).types
@@ -25,6 +25,7 @@ No type information for this code.import {} from "./b";
 No type information for this code.import {} from "./b.js";
 No type information for this code.import {} from "./b.ts";
 No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
 No type information for this code.
 No type information for this code.import {} from "./c.ts";
 No type information for this code.import {} from "./c.tsx";
diff --git a/tests/cases/conformance/moduleResolution/minimal_relative.ts b/tests/cases/conformance/moduleResolution/minimal_relative.ts
index 48fda19b7c3eb..b3428c435e48a 100644
--- a/tests/cases/conformance/moduleResolution/minimal_relative.ts
+++ b/tests/cases/conformance/moduleResolution/minimal_relative.ts
@@ -36,6 +36,7 @@ import {} from "./b";
 import {} from "./b.js";
 import {} from "./b.ts";
 import {} from "./b.d.ts";
+import type {} from "./b.d.ts";
 
 import {} from "./c.ts";
 import {} from "./c.tsx";

From f49a36851f8425d957a6b3259d4cd79479f6e605 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Wed, 14 Sep 2022 14:05:41 -0700
Subject: [PATCH 05/14] Update unit test

---
 src/testRunner/unittests/config/commandLineParsing.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/testRunner/unittests/config/commandLineParsing.ts b/src/testRunner/unittests/config/commandLineParsing.ts
index e2b48977106b6..07ecbb7393328 100644
--- a/src/testRunner/unittests/config/commandLineParsing.ts
+++ b/src/testRunner/unittests/config/commandLineParsing.ts
@@ -237,7 +237,7 @@ namespace ts {
                         start: undefined,
                         length: undefined,
                     }, {
-                        messageText: "Argument for '--moduleResolution' option must be: 'node', 'classic', 'node16', 'nodenext'.",
+                        messageText: "Argument for '--moduleResolution' option must be: 'node', 'classic', 'node16', 'nodenext', 'minimal'.",
                         category: Diagnostics.Argument_for_0_option_must_be_Colon_1.category,
                         code: Diagnostics.Argument_for_0_option_must_be_Colon_1.code,
 

From af03675a085d6b799b8b7ce7e8f6f4baf4008ea9 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Wed, 14 Sep 2022 16:52:42 -0700
Subject: [PATCH 06/14] Add explicit flag for importing from .ts extensions

---
 src/compiler/checker.ts                       |   4 +-
 src/compiler/commandLineParser.ts             |   8 ++
 src/compiler/diagnosticMessages.json          |  16 ++-
 src/compiler/moduleNameResolver.ts            |   8 +-
 src/compiler/program.ts                       |   4 +
 src/compiler/types.ts                         |   1 +
 src/testRunner/compilerRunner.ts              |   1 +
 .../minimal_pathsAndBaseUrl.errors.txt        |   1 +
 ...sextensions=false,noemit=false).errors.txt | 107 ++++++++++++++++++
 ...portingtsextensions=false,noemit=false).js |  64 +++++++++++
 ...ngtsextensions=false,noemit=false).symbols |  44 +++++++
 ...sextensions=false,noemit=false).trace.json |  68 +++++++++++
 ...tingtsextensions=false,noemit=false).types |  44 +++++++
 ...tsextensions=false,noemit=true).errors.txt | 105 +++++++++++++++++
 ...ingtsextensions=false,noemit=true).symbols |  44 +++++++
 ...tsextensions=false,noemit=true).trace.json |  68 +++++++++++
 ...rtingtsextensions=false,noemit=true).types |  44 +++++++
 ...tsextensions=true,noemit=false).errors.txt |  94 +++++++++++++++
 ...mportingtsextensions=true,noemit=false).js |  64 +++++++++++
 ...ingtsextensions=true,noemit=false).symbols |  44 +++++++
 ...tsextensions=true,noemit=false).trace.json |  68 +++++++++++
 ...rtingtsextensions=true,noemit=false).types |  44 +++++++
 ...gtsextensions=true,noemit=true).errors.txt |  90 +++++++++++++++
 ...tingtsextensions=true,noemit=true).symbols |  44 +++++++
 ...gtsextensions=true,noemit=true).trace.json |  68 +++++++++++
 ...ortingtsextensions=true,noemit=true).types |  44 +++++++
 .../minimal_pathsAndBaseUrl.ts                |   1 +
 .../moduleResolution/minimal_relative.ts      |   6 +
 28 files changed, 1190 insertions(+), 8 deletions(-)
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).errors.txt
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).js
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).symbols
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).trace.json
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).types
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).errors.txt
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).symbols
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).trace.json
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).types
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).errors.txt
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).js
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).symbols
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).trace.json
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).types
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).errors.txt
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).symbols
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).trace.json
 create mode 100644 tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).types

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index d7d6c3148b9e4..36e21f63f35d5 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3620,9 +3620,9 @@ namespace ts {
                             getSuggestedImportSource(Debug.checkDefined(tryExtractTSExtension(moduleReference))));
                     }
                 }
-                else if (resolvedModule.resolvedUsingTsExtension && !shouldAllowTsExtension(compilerOptions)) {
+                else if (resolvedModule.resolvedUsingTsExtension && !shouldAllowImportingTsExtension(compilerOptions, currentSourceFile.fileName)) {
                     const tsExtension = Debug.checkDefined(tryExtractTSExtension(moduleReference));
-                    errorOnTSExtensionImport(tsExtension);
+                    error(errorNode, Diagnostics.An_import_path_can_only_end_with_a_0_extension_when_allowImportingTsExtensions_is_enabled, tsExtension);
                 }
 
                 if (sourceFile.symbol) {
diff --git a/src/compiler/commandLineParser.ts b/src/compiler/commandLineParser.ts
index 541871714593f..f3ffc50336dc0 100644
--- a/src/compiler/commandLineParser.ts
+++ b/src/compiler/commandLineParser.ts
@@ -956,6 +956,14 @@ namespace ts {
             category: Diagnostics.Modules,
             description: Diagnostics.List_of_file_name_suffixes_to_search_when_resolving_a_module,
         },
+        {
+            name: "allowImportingTsExtensions",
+            type: "boolean",
+            affectsModuleResolution: true,
+            category: Diagnostics.Modules,
+            description: Diagnostics.Allow_imports_to_include_TypeScript_file_extensions_Requires_moduleResolution_minimal_and_either_noEmit_or_emitDeclarationOnly_to_be_set,
+            defaultValueDescription: false,
+        },
 
         // Source Maps
         {
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index 4d74c87d16799..c6614d6482b14 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -4229,6 +4229,14 @@
         "category": "Error",
         "code": 5095
     },
+    "Option 'allowImportingTsExtensions' can only be used when 'moduleResolution' is set to 'minimal' and either 'noEmit' or 'emitDeclarationOnly' is set.": {
+        "category": "Error",
+        "code": 5096
+    },
+    "An import path can only end with a '{0}' extension when 'allowImportingTsExtensions' is enabled.": {
+        "category": "Error",
+        "code": 5097
+    },
 
     "Generates a sourcemap for each corresponding '.d.ts' file.": {
         "category": "Message",
@@ -4451,10 +4459,6 @@
         "category": "Message",
         "code": 6066
     },
-    "Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6).": {
-        "category": "Message",
-        "code": 6069
-    },
     "Initializes a TypeScript project and creates a tsconfig.json file.": {
         "category": "Message",
         "code": 6070
@@ -5418,6 +5422,10 @@
         "category": "Message",
         "code": 6401
     },
+    "Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set.": {
+        "category": "Message",
+        "code": 6402
+    },
 
     "The expected type comes from property '{0}' which is declared here on type '{1}'": {
         "category": "Message",
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index c61ba110532bb..6fc614ab5dc1a 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -2716,8 +2716,12 @@ namespace ts {
       return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Minimal;
     }
 
-    export function shouldAllowTsExtension(compilerOptions: CompilerOptions) {
-        return shouldResolveTsExtension(compilerOptions) && !!compilerOptions.noEmit;
+    // Program errors validate that `noEmit` or `emitDeclarationOnly` is also set,
+    // so this function doesn't check them to avoid propagating errors.
+    export function shouldAllowImportingTsExtension(compilerOptions: CompilerOptions, fromFileName?: string) {
+        return shouldResolveTsExtension(compilerOptions) && (
+            !!compilerOptions.allowImportingTsExtensions ||
+            fromFileName && isDeclarationFileName(fromFileName));
     }
 
     /**
diff --git a/src/compiler/program.ts b/src/compiler/program.ts
index 412f307eae4bf..676c5507ee143 100644
--- a/src/compiler/program.ts
+++ b/src/compiler/program.ts
@@ -3657,6 +3657,10 @@ namespace ts {
                 createOptionValueDiagnostic("importsNotUsedAsValues", Diagnostics.Option_preserveValueImports_can_only_be_used_when_module_is_set_to_es2015_or_later);
             }
 
+            if (options.allowImportingTsExtensions && !(getEmitModuleResolutionKind(options) === ModuleResolutionKind.Minimal && (options.noEmit || options.emitDeclarationOnly))) {
+                createOptionValueDiagnostic("allowImportingTsExtensions", Diagnostics.Option_allowImportingTsExtensions_can_only_be_used_when_moduleResolution_is_set_to_minimal_and_either_noEmit_or_emitDeclarationOnly_is_set);
+            }
+
             // If the emit is enabled make sure that every output file is unique and not overwriting any of the input files
             if (!options.noEmit && !options.suppressOutputPathCheck) {
                 const emitHost = getEmitHost();
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
index fa3fdd92df5e0..2790fb700ffa3 100644
--- a/src/compiler/types.ts
+++ b/src/compiler/types.ts
@@ -6543,6 +6543,7 @@ namespace ts {
 
     export interface CompilerOptions {
         /*@internal*/ all?: boolean;
+        allowImportingTsExtensions?: boolean;
         allowJs?: boolean;
         /*@internal*/ allowNonTsExtensions?: boolean;
         allowSyntheticDefaultImports?: boolean;
diff --git a/src/testRunner/compilerRunner.ts b/src/testRunner/compilerRunner.ts
index 00daa90668848..22ae1b9c6e469 100644
--- a/src/testRunner/compilerRunner.ts
+++ b/src/testRunner/compilerRunner.ts
@@ -119,6 +119,7 @@ namespace Harness {
             "module",
             "moduleResolution",
             "moduleDetection",
+            "allowImportingTsExtensions",
             "target",
             "jsx",
             "noEmit",
diff --git a/tests/baselines/reference/minimal_pathsAndBaseUrl.errors.txt b/tests/baselines/reference/minimal_pathsAndBaseUrl.errors.txt
index a1b7074087d13..31490691952d2 100644
--- a/tests/baselines/reference/minimal_pathsAndBaseUrl.errors.txt
+++ b/tests/baselines/reference/minimal_pathsAndBaseUrl.errors.txt
@@ -6,6 +6,7 @@
       "compilerOptions": {
         "moduleResolution": "minimal",
         "noEmit": true,
+        "allowImportingTsExtensions": true,
         "baseUrl": ".",
         "paths": {
           "*": [
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).errors.txt b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).errors.txt
new file mode 100644
index 0000000000000..1a1ce3a5447b2
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).errors.txt
@@ -0,0 +1,107 @@
+error TS5056: Cannot write file 'dist/c.js' because it would be overwritten by multiple input files.
+error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+  The file is in the program because:
+    Root file specified for compilation
+error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+  The file is in the program because:
+    Root file specified for compilation
+/project/main.ts(1,16): error TS2307: Cannot find module './a' or its corresponding type declarations.
+/project/main.ts(3,16): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(5,16): error TS2307: Cannot find module './b' or its corresponding type declarations.
+/project/main.ts(7,16): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(8,16): error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+/project/main.ts(11,16): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(12,16): error TS5097: An import path can only end with a '.tsx' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(12,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+/project/main.ts(14,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
+/project/main.ts(15,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+/project/main.ts(16,16): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(18,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
+/project/types.d.ts(2,16): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+/project/types.d.ts(3,21): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+
+
+!!! error TS5056: Cannot write file 'dist/c.js' because it would be overwritten by multiple input files.
+!!! error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+!!! error TS6231:   The file is in the program because:
+!!! error TS6231:     Root file specified for compilation
+!!! error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+!!! error TS6504:   The file is in the program because:
+!!! error TS6504:     Root file specified for compilation
+==== /project/a.ts (0 errors) ====
+    export {};
+    
+==== /project/b.ts (0 errors) ====
+    export {};
+    
+==== /project/b.js (0 errors) ====
+    export {};
+    
+==== /project/b.d.ts (0 errors) ====
+    export {};
+    
+==== /project/c.ts (0 errors) ====
+    export {};
+    
+==== /project/c.tsx (0 errors) ====
+    export {};
+    
+==== /project/d/index.ts (0 errors) ====
+    export {};
+    
+==== /project/e (0 errors) ====
+    export {};
+    
+==== /project/main.ts (12 errors) ====
+    import {} from "./a";
+                   ~~~~~
+!!! error TS2307: Cannot find module './a' or its corresponding type declarations.
+    import {} from "./a.js";
+    import {} from "./a.ts";
+                   ~~~~~~~~
+!!! error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+    
+    import {} from "./b";
+                   ~~~~~
+!!! error TS2307: Cannot find module './b' or its corresponding type declarations.
+    import {} from "./b.js";
+    import {} from "./b.ts";
+                   ~~~~~~~~
+!!! error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+    import {} from "./b.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+    import type {} from "./b.d.ts";
+    
+    import {} from "./c.ts";
+                   ~~~~~~~~
+!!! error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+    import {} from "./c.tsx";
+                   ~~~~~~~~~
+!!! error TS5097: An import path can only end with a '.tsx' extension when 'allowImportingTsExtensions' is enabled.
+                   ~~~~~~~~~
+!!! error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+    
+    import {} from "./d";
+                   ~~~~~
+!!! error TS2307: Cannot find module './d' or its corresponding type declarations.
+    import {} from "./d/index";
+                   ~~~~~~~~~~~
+!!! error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+    import {} from "./d/index.ts";
+                   ~~~~~~~~~~~~~~
+!!! error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+    
+    import {} from "./e";
+                   ~~~~~
+!!! error TS2307: Cannot find module './e' or its corresponding type declarations.
+    
+==== /project/types.d.ts (2 errors) ====
+    import {} from "./a.ts";
+    import {} from "./a.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+    import type {} from "./a.d.ts";
+                        ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).js b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).js
new file mode 100644
index 0000000000000..2eeeabf051a24
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).js
@@ -0,0 +1,64 @@
+//// [tests/cases/conformance/moduleResolution/minimal_relative.ts] ////
+
+//// [a.ts]
+export {};
+
+//// [b.ts]
+export {};
+
+//// [b.js]
+export {};
+
+//// [b.d.ts]
+export {};
+
+//// [c.ts]
+export {};
+
+//// [c.tsx]
+export {};
+
+//// [index.ts]
+export {};
+
+//// [e]
+export {};
+
+//// [main.ts]
+import {} from "./a";
+import {} from "./a.js";
+import {} from "./a.ts";
+
+import {} from "./b";
+import {} from "./b.js";
+import {} from "./b.ts";
+import {} from "./b.d.ts";
+import type {} from "./b.d.ts";
+
+import {} from "./c.ts";
+import {} from "./c.tsx";
+
+import {} from "./d";
+import {} from "./d/index";
+import {} from "./d/index.ts";
+
+import {} from "./e";
+
+//// [types.d.ts]
+import {} from "./a.ts";
+import {} from "./a.d.ts";
+import type {} from "./a.d.ts";
+
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+//// [b.js]
+"use strict";
+exports.__esModule = true;
+//// [index.js]
+"use strict";
+exports.__esModule = true;
+//// [main.js]
+"use strict";
+exports.__esModule = true;
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).symbols b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).symbols
new file mode 100644
index 0000000000000..8087e521944d1
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).symbols
@@ -0,0 +1,44 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.=== /project/types.d.ts ===
+import {} from "./a.ts";
+No type information for this code.import {} from "./a.d.ts";
+No type information for this code.import type {} from "./a.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).trace.json b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).trace.json
new file mode 100644
index 0000000000000..40a02fe86a714
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).trace.json
@@ -0,0 +1,68 @@
+[
+    "======== Resolving module './a' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './a' was not resolved. ========",
+    "======== Resolving module './a.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.js' has a '.js' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.js' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.ts' has a '.ts' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './b' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './b' was not resolved. ========",
+    "======== Resolving module './b.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.js' has a '.js' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.js' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.ts' has a '.ts' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.ts' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.d.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/b.d.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.d.ts' was successfully resolved to '/project/b.d.ts'. ========",
+    "======== Resolving module './c.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.ts' has a '.ts' extension - stripping it.",
+    "File '/project/c.ts' exist - use it as a name resolution result.",
+    "======== Module name './c.ts' was successfully resolved to '/project/c.ts'. ========",
+    "======== Resolving module './c.tsx' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.tsx' has a '.tsx' extension - stripping it.",
+    "File '/project/c.tsx' exist - use it as a name resolution result.",
+    "======== Module name './c.tsx' was successfully resolved to '/project/c.tsx'. ========",
+    "======== Resolving module './d' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d' was not resolved. ========",
+    "======== Resolving module './d/index' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d/index' was not resolved. ========",
+    "======== Resolving module './d/index.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/d/index.ts' has a '.ts' extension - stripping it.",
+    "File '/project/d/index.ts' exist - use it as a name resolution result.",
+    "======== Module name './d/index.ts' was successfully resolved to '/project/d/index.ts'. ========",
+    "======== Resolving module './e' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './e' was not resolved. ========",
+    "======== Resolving module './a.ts' from '/project/types.d.ts'. ========",
+    "Resolution for module './a.ts' was found in cache from location '/project'.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.d.ts' from '/project/types.d.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/a.d.ts' does not exist.",
+    "File name '/project/a.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/a.js' does not exist.",
+    "File '/project/a.jsx' does not exist.",
+    "======== Module name './a.d.ts' was not resolved. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).types b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).types
new file mode 100644
index 0000000000000..8087e521944d1
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=false).types
@@ -0,0 +1,44 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.=== /project/types.d.ts ===
+import {} from "./a.ts";
+No type information for this code.import {} from "./a.d.ts";
+No type information for this code.import type {} from "./a.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).errors.txt b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).errors.txt
new file mode 100644
index 0000000000000..be1af8b2bad51
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).errors.txt
@@ -0,0 +1,105 @@
+error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+  The file is in the program because:
+    Root file specified for compilation
+error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+  The file is in the program because:
+    Root file specified for compilation
+/project/main.ts(1,16): error TS2307: Cannot find module './a' or its corresponding type declarations.
+/project/main.ts(3,16): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(5,16): error TS2307: Cannot find module './b' or its corresponding type declarations.
+/project/main.ts(7,16): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(8,16): error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+/project/main.ts(11,16): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(12,16): error TS5097: An import path can only end with a '.tsx' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(12,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+/project/main.ts(14,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
+/project/main.ts(15,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+/project/main.ts(16,16): error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+/project/main.ts(18,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
+/project/types.d.ts(2,16): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+/project/types.d.ts(3,21): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+
+
+!!! error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+!!! error TS6231:   The file is in the program because:
+!!! error TS6231:     Root file specified for compilation
+!!! error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+!!! error TS6504:   The file is in the program because:
+!!! error TS6504:     Root file specified for compilation
+==== /project/a.ts (0 errors) ====
+    export {};
+    
+==== /project/b.ts (0 errors) ====
+    export {};
+    
+==== /project/b.js (0 errors) ====
+    export {};
+    
+==== /project/b.d.ts (0 errors) ====
+    export {};
+    
+==== /project/c.ts (0 errors) ====
+    export {};
+    
+==== /project/c.tsx (0 errors) ====
+    export {};
+    
+==== /project/d/index.ts (0 errors) ====
+    export {};
+    
+==== /project/e (0 errors) ====
+    export {};
+    
+==== /project/main.ts (12 errors) ====
+    import {} from "./a";
+                   ~~~~~
+!!! error TS2307: Cannot find module './a' or its corresponding type declarations.
+    import {} from "./a.js";
+    import {} from "./a.ts";
+                   ~~~~~~~~
+!!! error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+    
+    import {} from "./b";
+                   ~~~~~
+!!! error TS2307: Cannot find module './b' or its corresponding type declarations.
+    import {} from "./b.js";
+    import {} from "./b.ts";
+                   ~~~~~~~~
+!!! error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+    import {} from "./b.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+    import type {} from "./b.d.ts";
+    
+    import {} from "./c.ts";
+                   ~~~~~~~~
+!!! error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+    import {} from "./c.tsx";
+                   ~~~~~~~~~
+!!! error TS5097: An import path can only end with a '.tsx' extension when 'allowImportingTsExtensions' is enabled.
+                   ~~~~~~~~~
+!!! error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+    
+    import {} from "./d";
+                   ~~~~~
+!!! error TS2307: Cannot find module './d' or its corresponding type declarations.
+    import {} from "./d/index";
+                   ~~~~~~~~~~~
+!!! error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+    import {} from "./d/index.ts";
+                   ~~~~~~~~~~~~~~
+!!! error TS5097: An import path can only end with a '.ts' extension when 'allowImportingTsExtensions' is enabled.
+    
+    import {} from "./e";
+                   ~~~~~
+!!! error TS2307: Cannot find module './e' or its corresponding type declarations.
+    
+==== /project/types.d.ts (2 errors) ====
+    import {} from "./a.ts";
+    import {} from "./a.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+    import type {} from "./a.d.ts";
+                        ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).symbols b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).symbols
new file mode 100644
index 0000000000000..8087e521944d1
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).symbols
@@ -0,0 +1,44 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.=== /project/types.d.ts ===
+import {} from "./a.ts";
+No type information for this code.import {} from "./a.d.ts";
+No type information for this code.import type {} from "./a.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).trace.json b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).trace.json
new file mode 100644
index 0000000000000..40a02fe86a714
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).trace.json
@@ -0,0 +1,68 @@
+[
+    "======== Resolving module './a' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './a' was not resolved. ========",
+    "======== Resolving module './a.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.js' has a '.js' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.js' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.ts' has a '.ts' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './b' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './b' was not resolved. ========",
+    "======== Resolving module './b.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.js' has a '.js' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.js' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.ts' has a '.ts' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.ts' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.d.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/b.d.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.d.ts' was successfully resolved to '/project/b.d.ts'. ========",
+    "======== Resolving module './c.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.ts' has a '.ts' extension - stripping it.",
+    "File '/project/c.ts' exist - use it as a name resolution result.",
+    "======== Module name './c.ts' was successfully resolved to '/project/c.ts'. ========",
+    "======== Resolving module './c.tsx' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.tsx' has a '.tsx' extension - stripping it.",
+    "File '/project/c.tsx' exist - use it as a name resolution result.",
+    "======== Module name './c.tsx' was successfully resolved to '/project/c.tsx'. ========",
+    "======== Resolving module './d' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d' was not resolved. ========",
+    "======== Resolving module './d/index' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d/index' was not resolved. ========",
+    "======== Resolving module './d/index.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/d/index.ts' has a '.ts' extension - stripping it.",
+    "File '/project/d/index.ts' exist - use it as a name resolution result.",
+    "======== Module name './d/index.ts' was successfully resolved to '/project/d/index.ts'. ========",
+    "======== Resolving module './e' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './e' was not resolved. ========",
+    "======== Resolving module './a.ts' from '/project/types.d.ts'. ========",
+    "Resolution for module './a.ts' was found in cache from location '/project'.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.d.ts' from '/project/types.d.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/a.d.ts' does not exist.",
+    "File name '/project/a.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/a.js' does not exist.",
+    "File '/project/a.jsx' does not exist.",
+    "======== Module name './a.d.ts' was not resolved. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).types b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).types
new file mode 100644
index 0000000000000..8087e521944d1
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=false,noemit=true).types
@@ -0,0 +1,44 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.=== /project/types.d.ts ===
+import {} from "./a.ts";
+No type information for this code.import {} from "./a.d.ts";
+No type information for this code.import type {} from "./a.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).errors.txt b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).errors.txt
new file mode 100644
index 0000000000000..68fea4b6506d7
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).errors.txt
@@ -0,0 +1,94 @@
+error TS5056: Cannot write file 'dist/c.js' because it would be overwritten by multiple input files.
+error TS5096: Option 'allowImportingTsExtensions' can only be used when 'moduleResolution' is set to 'minimal' and either 'noEmit' or 'emitDeclarationOnly' is set.
+error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+  The file is in the program because:
+    Root file specified for compilation
+error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+  The file is in the program because:
+    Root file specified for compilation
+/project/main.ts(1,16): error TS2307: Cannot find module './a' or its corresponding type declarations.
+/project/main.ts(5,16): error TS2307: Cannot find module './b' or its corresponding type declarations.
+/project/main.ts(8,16): error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+/project/main.ts(12,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+/project/main.ts(14,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
+/project/main.ts(15,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+/project/main.ts(18,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
+/project/types.d.ts(2,16): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+/project/types.d.ts(3,21): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+
+
+!!! error TS5056: Cannot write file 'dist/c.js' because it would be overwritten by multiple input files.
+!!! error TS5096: Option 'allowImportingTsExtensions' can only be used when 'moduleResolution' is set to 'minimal' and either 'noEmit' or 'emitDeclarationOnly' is set.
+!!! error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+!!! error TS6231:   The file is in the program because:
+!!! error TS6231:     Root file specified for compilation
+!!! error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+!!! error TS6504:   The file is in the program because:
+!!! error TS6504:     Root file specified for compilation
+==== /project/a.ts (0 errors) ====
+    export {};
+    
+==== /project/b.ts (0 errors) ====
+    export {};
+    
+==== /project/b.js (0 errors) ====
+    export {};
+    
+==== /project/b.d.ts (0 errors) ====
+    export {};
+    
+==== /project/c.ts (0 errors) ====
+    export {};
+    
+==== /project/c.tsx (0 errors) ====
+    export {};
+    
+==== /project/d/index.ts (0 errors) ====
+    export {};
+    
+==== /project/e (0 errors) ====
+    export {};
+    
+==== /project/main.ts (7 errors) ====
+    import {} from "./a";
+                   ~~~~~
+!!! error TS2307: Cannot find module './a' or its corresponding type declarations.
+    import {} from "./a.js";
+    import {} from "./a.ts";
+    
+    import {} from "./b";
+                   ~~~~~
+!!! error TS2307: Cannot find module './b' or its corresponding type declarations.
+    import {} from "./b.js";
+    import {} from "./b.ts";
+    import {} from "./b.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+    import type {} from "./b.d.ts";
+    
+    import {} from "./c.ts";
+    import {} from "./c.tsx";
+                   ~~~~~~~~~
+!!! error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+    
+    import {} from "./d";
+                   ~~~~~
+!!! error TS2307: Cannot find module './d' or its corresponding type declarations.
+    import {} from "./d/index";
+                   ~~~~~~~~~~~
+!!! error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+    import {} from "./d/index.ts";
+    
+    import {} from "./e";
+                   ~~~~~
+!!! error TS2307: Cannot find module './e' or its corresponding type declarations.
+    
+==== /project/types.d.ts (2 errors) ====
+    import {} from "./a.ts";
+    import {} from "./a.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+    import type {} from "./a.d.ts";
+                        ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).js b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).js
new file mode 100644
index 0000000000000..2eeeabf051a24
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).js
@@ -0,0 +1,64 @@
+//// [tests/cases/conformance/moduleResolution/minimal_relative.ts] ////
+
+//// [a.ts]
+export {};
+
+//// [b.ts]
+export {};
+
+//// [b.js]
+export {};
+
+//// [b.d.ts]
+export {};
+
+//// [c.ts]
+export {};
+
+//// [c.tsx]
+export {};
+
+//// [index.ts]
+export {};
+
+//// [e]
+export {};
+
+//// [main.ts]
+import {} from "./a";
+import {} from "./a.js";
+import {} from "./a.ts";
+
+import {} from "./b";
+import {} from "./b.js";
+import {} from "./b.ts";
+import {} from "./b.d.ts";
+import type {} from "./b.d.ts";
+
+import {} from "./c.ts";
+import {} from "./c.tsx";
+
+import {} from "./d";
+import {} from "./d/index";
+import {} from "./d/index.ts";
+
+import {} from "./e";
+
+//// [types.d.ts]
+import {} from "./a.ts";
+import {} from "./a.d.ts";
+import type {} from "./a.d.ts";
+
+
+//// [a.js]
+"use strict";
+exports.__esModule = true;
+//// [b.js]
+"use strict";
+exports.__esModule = true;
+//// [index.js]
+"use strict";
+exports.__esModule = true;
+//// [main.js]
+"use strict";
+exports.__esModule = true;
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).symbols b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).symbols
new file mode 100644
index 0000000000000..8087e521944d1
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).symbols
@@ -0,0 +1,44 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.=== /project/types.d.ts ===
+import {} from "./a.ts";
+No type information for this code.import {} from "./a.d.ts";
+No type information for this code.import type {} from "./a.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).trace.json b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).trace.json
new file mode 100644
index 0000000000000..40a02fe86a714
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).trace.json
@@ -0,0 +1,68 @@
+[
+    "======== Resolving module './a' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './a' was not resolved. ========",
+    "======== Resolving module './a.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.js' has a '.js' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.js' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.ts' has a '.ts' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './b' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './b' was not resolved. ========",
+    "======== Resolving module './b.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.js' has a '.js' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.js' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.ts' has a '.ts' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.ts' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.d.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/b.d.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.d.ts' was successfully resolved to '/project/b.d.ts'. ========",
+    "======== Resolving module './c.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.ts' has a '.ts' extension - stripping it.",
+    "File '/project/c.ts' exist - use it as a name resolution result.",
+    "======== Module name './c.ts' was successfully resolved to '/project/c.ts'. ========",
+    "======== Resolving module './c.tsx' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.tsx' has a '.tsx' extension - stripping it.",
+    "File '/project/c.tsx' exist - use it as a name resolution result.",
+    "======== Module name './c.tsx' was successfully resolved to '/project/c.tsx'. ========",
+    "======== Resolving module './d' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d' was not resolved. ========",
+    "======== Resolving module './d/index' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d/index' was not resolved. ========",
+    "======== Resolving module './d/index.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/d/index.ts' has a '.ts' extension - stripping it.",
+    "File '/project/d/index.ts' exist - use it as a name resolution result.",
+    "======== Module name './d/index.ts' was successfully resolved to '/project/d/index.ts'. ========",
+    "======== Resolving module './e' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './e' was not resolved. ========",
+    "======== Resolving module './a.ts' from '/project/types.d.ts'. ========",
+    "Resolution for module './a.ts' was found in cache from location '/project'.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.d.ts' from '/project/types.d.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/a.d.ts' does not exist.",
+    "File name '/project/a.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/a.js' does not exist.",
+    "File '/project/a.jsx' does not exist.",
+    "======== Module name './a.d.ts' was not resolved. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).types b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).types
new file mode 100644
index 0000000000000..8087e521944d1
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=false).types
@@ -0,0 +1,44 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.=== /project/types.d.ts ===
+import {} from "./a.ts";
+No type information for this code.import {} from "./a.d.ts";
+No type information for this code.import type {} from "./a.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).errors.txt b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).errors.txt
new file mode 100644
index 0000000000000..3ae5b03e5a120
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).errors.txt
@@ -0,0 +1,90 @@
+error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+  The file is in the program because:
+    Root file specified for compilation
+error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+  The file is in the program because:
+    Root file specified for compilation
+/project/main.ts(1,16): error TS2307: Cannot find module './a' or its corresponding type declarations.
+/project/main.ts(5,16): error TS2307: Cannot find module './b' or its corresponding type declarations.
+/project/main.ts(8,16): error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+/project/main.ts(12,16): error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+/project/main.ts(14,16): error TS2307: Cannot find module './d' or its corresponding type declarations.
+/project/main.ts(15,16): error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+/project/main.ts(18,16): error TS2307: Cannot find module './e' or its corresponding type declarations.
+/project/types.d.ts(2,16): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+/project/types.d.ts(3,21): error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+
+
+!!! error TS6231: Could not resolve the path '/project/e' with the extensions: '.ts', '.tsx', '.d.ts', '.cts', '.d.cts', '.mts', '.d.mts'.
+!!! error TS6231:   The file is in the program because:
+!!! error TS6231:     Root file specified for compilation
+!!! error TS6504: File '/project/b.js' is a JavaScript file. Did you mean to enable the 'allowJs' option?
+!!! error TS6504:   The file is in the program because:
+!!! error TS6504:     Root file specified for compilation
+==== /project/a.ts (0 errors) ====
+    export {};
+    
+==== /project/b.ts (0 errors) ====
+    export {};
+    
+==== /project/b.js (0 errors) ====
+    export {};
+    
+==== /project/b.d.ts (0 errors) ====
+    export {};
+    
+==== /project/c.ts (0 errors) ====
+    export {};
+    
+==== /project/c.tsx (0 errors) ====
+    export {};
+    
+==== /project/d/index.ts (0 errors) ====
+    export {};
+    
+==== /project/e (0 errors) ====
+    export {};
+    
+==== /project/main.ts (7 errors) ====
+    import {} from "./a";
+                   ~~~~~
+!!! error TS2307: Cannot find module './a' or its corresponding type declarations.
+    import {} from "./a.js";
+    import {} from "./a.ts";
+    
+    import {} from "./b";
+                   ~~~~~
+!!! error TS2307: Cannot find module './b' or its corresponding type declarations.
+    import {} from "./b.js";
+    import {} from "./b.ts";
+    import {} from "./b.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2845: A declaration file cannot be imported without 'import type'. Did you mean to import an implementation file './b.js' instead?
+    import type {} from "./b.d.ts";
+    
+    import {} from "./c.ts";
+    import {} from "./c.tsx";
+                   ~~~~~~~~~
+!!! error TS6142: Module './c.tsx' was resolved to '/project/c.tsx', but '--jsx' is not set.
+    
+    import {} from "./d";
+                   ~~~~~
+!!! error TS2307: Cannot find module './d' or its corresponding type declarations.
+    import {} from "./d/index";
+                   ~~~~~~~~~~~
+!!! error TS2307: Cannot find module './d/index' or its corresponding type declarations.
+    import {} from "./d/index.ts";
+    
+    import {} from "./e";
+                   ~~~~~
+!!! error TS2307: Cannot find module './e' or its corresponding type declarations.
+    
+==== /project/types.d.ts (2 errors) ====
+    import {} from "./a.ts";
+    import {} from "./a.d.ts";
+                   ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+    import type {} from "./a.d.ts";
+                        ~~~~~~~~~~
+!!! error TS2691: An import path cannot end with a '.d.ts' extension. Consider importing './a.js' instead.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).symbols b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).symbols
new file mode 100644
index 0000000000000..8087e521944d1
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).symbols
@@ -0,0 +1,44 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.=== /project/types.d.ts ===
+import {} from "./a.ts";
+No type information for this code.import {} from "./a.d.ts";
+No type information for this code.import type {} from "./a.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).trace.json b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).trace.json
new file mode 100644
index 0000000000000..40a02fe86a714
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).trace.json
@@ -0,0 +1,68 @@
+[
+    "======== Resolving module './a' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './a' was not resolved. ========",
+    "======== Resolving module './a.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.js' has a '.js' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.js' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.ts' has a '.ts' extension - stripping it.",
+    "File '/project/a.ts' exist - use it as a name resolution result.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './b' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './b' was not resolved. ========",
+    "======== Resolving module './b.js' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.js' has a '.js' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.js' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.ts' has a '.ts' extension - stripping it.",
+    "File '/project/b.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.ts' was successfully resolved to '/project/b.ts'. ========",
+    "======== Resolving module './b.d.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/b.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/b.d.ts' exist - use it as a name resolution result.",
+    "======== Module name './b.d.ts' was successfully resolved to '/project/b.d.ts'. ========",
+    "======== Resolving module './c.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.ts' has a '.ts' extension - stripping it.",
+    "File '/project/c.ts' exist - use it as a name resolution result.",
+    "======== Module name './c.ts' was successfully resolved to '/project/c.ts'. ========",
+    "======== Resolving module './c.tsx' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/c.tsx' has a '.tsx' extension - stripping it.",
+    "File '/project/c.tsx' exist - use it as a name resolution result.",
+    "======== Module name './c.tsx' was successfully resolved to '/project/c.tsx'. ========",
+    "======== Resolving module './d' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d' was not resolved. ========",
+    "======== Resolving module './d/index' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './d/index' was not resolved. ========",
+    "======== Resolving module './d/index.ts' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/d/index.ts' has a '.ts' extension - stripping it.",
+    "File '/project/d/index.ts' exist - use it as a name resolution result.",
+    "======== Module name './d/index.ts' was successfully resolved to '/project/d/index.ts'. ========",
+    "======== Resolving module './e' from '/project/main.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "======== Module name './e' was not resolved. ========",
+    "======== Resolving module './a.ts' from '/project/types.d.ts'. ========",
+    "Resolution for module './a.ts' was found in cache from location '/project'.",
+    "======== Module name './a.ts' was successfully resolved to '/project/a.ts'. ========",
+    "======== Resolving module './a.d.ts' from '/project/types.d.ts'. ========",
+    "Explicitly specified module resolution kind: 'Minimal'.",
+    "File name '/project/a.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/a.d.ts' does not exist.",
+    "File name '/project/a.d.ts' has a '.d.ts' extension - stripping it.",
+    "File '/project/a.js' does not exist.",
+    "File '/project/a.jsx' does not exist.",
+    "======== Module name './a.d.ts' was not resolved. ========"
+]
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).types b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).types
new file mode 100644
index 0000000000000..8087e521944d1
--- /dev/null
+++ b/tests/baselines/reference/minimal_relative(allowimportingtsextensions=true,noemit=true).types
@@ -0,0 +1,44 @@
+=== /project/a.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/b.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/c.tsx ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/d/index.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /project/main.ts ===
+import {} from "./a";
+No type information for this code.import {} from "./a.js";
+No type information for this code.import {} from "./a.ts";
+No type information for this code.
+No type information for this code.import {} from "./b";
+No type information for this code.import {} from "./b.js";
+No type information for this code.import {} from "./b.ts";
+No type information for this code.import {} from "./b.d.ts";
+No type information for this code.import type {} from "./b.d.ts";
+No type information for this code.
+No type information for this code.import {} from "./c.ts";
+No type information for this code.import {} from "./c.tsx";
+No type information for this code.
+No type information for this code.import {} from "./d";
+No type information for this code.import {} from "./d/index";
+No type information for this code.import {} from "./d/index.ts";
+No type information for this code.
+No type information for this code.import {} from "./e";
+No type information for this code.
+No type information for this code.=== /project/types.d.ts ===
+import {} from "./a.ts";
+No type information for this code.import {} from "./a.d.ts";
+No type information for this code.import type {} from "./a.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/cases/conformance/moduleResolution/minimal_pathsAndBaseUrl.ts b/tests/cases/conformance/moduleResolution/minimal_pathsAndBaseUrl.ts
index a7fb1a2c4ebb6..74ae8ffcde21e 100644
--- a/tests/cases/conformance/moduleResolution/minimal_pathsAndBaseUrl.ts
+++ b/tests/cases/conformance/moduleResolution/minimal_pathsAndBaseUrl.ts
@@ -6,6 +6,7 @@
   "compilerOptions": {
     "moduleResolution": "minimal",
     "noEmit": true,
+    "allowImportingTsExtensions": true,
     "baseUrl": ".",
     "paths": {
       "*": [
diff --git a/tests/cases/conformance/moduleResolution/minimal_relative.ts b/tests/cases/conformance/moduleResolution/minimal_relative.ts
index b3428c435e48a..21eb4828223f5 100644
--- a/tests/cases/conformance/moduleResolution/minimal_relative.ts
+++ b/tests/cases/conformance/moduleResolution/minimal_relative.ts
@@ -1,6 +1,7 @@
 // @moduleResolution: minimal
 // @outDir: dist
 // @noEmit: true,false
+// @allowImportingTsExtensions: true,false
 // @traceResolution: true
 
 // @Filename: /project/a.ts
@@ -46,3 +47,8 @@ import {} from "./d/index";
 import {} from "./d/index.ts";
 
 import {} from "./e";
+
+// @Filename: /project/types.d.ts
+import {} from "./a.ts";
+import {} from "./a.d.ts";
+import type {} from "./a.d.ts";

From 496ef994efcde07a1bceff1c3651e18dc647dfa1 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Thu, 15 Sep 2022 13:35:48 -0700
Subject: [PATCH 07/14] Add module specifier resolution changes

---
 src/compiler/moduleSpecifiers.ts              | 115 +++++++++++-------
 .../reference/api/tsserverlibrary.d.ts        |   3 +-
 tests/baselines/reference/api/typescript.d.ts |   3 +-
 .../allowImportingTsExtensions/tsconfig.json  |   5 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../tsconfig.json                             |   1 +
 .../declarationDir-is-specified.js            |   1 +
 ...-outDir-and-declarationDir-is-specified.js |   1 +
 .../when-outDir-is-specified.js               |   1 +
 .../with-outFile.js                           |   1 +
 ...e-is-specified-with-declaration-enabled.js |   1 +
 .../without-outDir-or-outFile-is-specified.js |   1 +
 21 files changed, 94 insertions(+), 49 deletions(-)
 create mode 100644 tests/baselines/reference/showConfig/Shows tsconfig for single option/allowImportingTsExtensions/tsconfig.json

diff --git a/src/compiler/moduleSpecifiers.ts b/src/compiler/moduleSpecifiers.ts
index 32640fcb81579..1f560927e3e55 100644
--- a/src/compiler/moduleSpecifiers.ts
+++ b/src/compiler/moduleSpecifiers.ts
@@ -8,44 +8,76 @@ namespace ts.moduleSpecifiers {
     // Processed preferences
     interface Preferences {
         readonly relativePreference: RelativePreference;
-        readonly ending: Ending;
+        /**
+         * @param syntaxImpliedNodeFormat Used when the import syntax implies ESM or CJS irrespective of the mode of the file.
+         */
+        getAllowedEndingsInPrefererredOrder(syntaxImpliedNodeFormat?: SourceFile["impliedNodeFormat"]): Ending[];
     }
 
-    function getPreferences(host: ModuleSpecifierResolutionHost, { importModuleSpecifierPreference, importModuleSpecifierEnding }: UserPreferences, compilerOptions: CompilerOptions, importingSourceFile: SourceFile): Preferences {
+    function getPreferences(
+        host: ModuleSpecifierResolutionHost,
+        { importModuleSpecifierPreference, importModuleSpecifierEnding }: UserPreferences,
+        compilerOptions: CompilerOptions,
+        importingSourceFile: SourceFile,
+        oldImportSpecifier?: string,
+    ): Preferences {
+        const preferredEnding = getPreferredEnding();
         return {
             relativePreference:
+                oldImportSpecifier !== undefined ? (isExternalModuleNameRelative(oldImportSpecifier) ?
+                    RelativePreference.Relative :
+                    RelativePreference.NonRelative) :
                 importModuleSpecifierPreference === "relative" ? RelativePreference.Relative :
                 importModuleSpecifierPreference === "non-relative" ? RelativePreference.NonRelative :
                 importModuleSpecifierPreference === "project-relative" ? RelativePreference.ExternalNonRelative :
                 RelativePreference.Shortest,
-            ending: getEnding(),
+            getAllowedEndingsInPrefererredOrder: syntaxImpliedNodeFormat => {
+                if (syntaxImpliedNodeFormat === ModuleKind.ESNext ||
+                    getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Minimal ||
+                    isFormatRequiringExtensions()
+                ) {
+                    return [Ending.JsExtension];
+                }
+                if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic) {
+                    return [Ending.Index, Ending.JsExtension];
+                }
+                switch (preferredEnding) {
+                    case Ending.JsExtension: return [Ending.JsExtension, Ending.Minimal, Ending.Index];
+                    case Ending.Index: return [Ending.Index, Ending.Minimal, Ending.JsExtension];
+                    case Ending.Minimal: return [Ending.Minimal, Ending.Index, Ending.JsExtension];
+                    default: Debug.assertNever(preferredEnding);
+                }
+            },
         };
-        function getEnding(): Ending {
+
+        function getPreferredEnding(): Ending {
+            if (oldImportSpecifier !== undefined) {
+                if (hasJSFileExtension(oldImportSpecifier)) return Ending.JsExtension;
+                if (endsWith(oldImportSpecifier, "/index")) return Ending.Index;
+            }
             switch (importModuleSpecifierEnding) {
                 case "minimal": return Ending.Minimal;
                 case "index": return Ending.Index;
                 case "js": return Ending.JsExtension;
-                default: return usesJsExtensionOnImports(importingSourceFile) || isFormatRequiringExtensions(compilerOptions, importingSourceFile.path, host) ? Ending.JsExtension
-                    : getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.NodeJs ? Ending.Index : Ending.Minimal;
+                default: return usesJsExtensionOnImports(importingSourceFile) ? Ending.JsExtension : Ending.Minimal;
             }
         }
-    }
-
-    function getPreferencesForUpdate(compilerOptions: CompilerOptions, oldImportSpecifier: string, importingSourceFileName: Path, host: ModuleSpecifierResolutionHost): Preferences {
-        return {
-            relativePreference: isExternalModuleNameRelative(oldImportSpecifier) ? RelativePreference.Relative : RelativePreference.NonRelative,
-            ending: hasJSFileExtension(oldImportSpecifier) || isFormatRequiringExtensions(compilerOptions, importingSourceFileName, host) ?
-                Ending.JsExtension :
-                getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.NodeJs || endsWith(oldImportSpecifier, "index") ? Ending.Index : Ending.Minimal,
-        };
-    }
 
-    function isFormatRequiringExtensions(compilerOptions: CompilerOptions, importingSourceFileName: Path, host: ModuleSpecifierResolutionHost) {
-        if (getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Node16
-        && getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.NodeNext) {
-            return false;
+        function isFormatRequiringExtensions() {
+            switch (getEmitModuleResolutionKind(compilerOptions)) {
+                case ModuleResolutionKind.Minimal:
+                    return true;
+                case ModuleResolutionKind.Node16:
+                case ModuleResolutionKind.NodeNext:
+                    return getImpliedNodeFormatForFile(
+                        importingSourceFile.path,
+                        host.getPackageJsonInfoCache?.(),
+                        getModuleResolutionHost(host), compilerOptions,
+                    ) !== ModuleKind.CommonJS;
+                default:
+                    return false;
+            }
         }
-        return getImpliedNodeFormatForFile(importingSourceFileName, host.getPackageJsonInfoCache?.(), getModuleResolutionHost(host), compilerOptions) !== ModuleKind.CommonJS;
     }
 
     function getModuleResolutionHost(host: ModuleSpecifierResolutionHost): ModuleResolutionHost {
@@ -72,7 +104,7 @@ namespace ts.moduleSpecifiers {
         oldImportSpecifier: string,
         options: ModuleSpecifierOptions = {},
     ): string | undefined {
-        const res = getModuleSpecifierWorker(compilerOptions, importingSourceFile, importingSourceFileName, toFileName, host, getPreferencesForUpdate(compilerOptions, oldImportSpecifier, importingSourceFileName, host), {}, options);
+        const res = getModuleSpecifierWorker(compilerOptions, importingSourceFile, importingSourceFileName, toFileName, host, getPreferences(host, {}, compilerOptions, importingSourceFile, oldImportSpecifier), {}, options);
         if (res === oldImportSpecifier) return undefined;
         return res;
     }
@@ -293,11 +325,13 @@ namespace ts.moduleSpecifiers {
         return { getCanonicalFileName, importingSourceFileName, sourceDirectory };
     }
 
-    function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: SourceFile["impliedNodeFormat"], { ending, relativePreference }: Preferences): string {
+    function getLocalModuleSpecifier(moduleFileName: string, info: Info, compilerOptions: CompilerOptions, host: ModuleSpecifierResolutionHost, importMode: SourceFile["impliedNodeFormat"], { getAllowedEndingsInPrefererredOrder, relativePreference }: Preferences): string {
         const { baseUrl, paths, rootDirs } = compilerOptions;
         const { sourceDirectory, getCanonicalFileName } = info;
+        const allowedEndings = getAllowedEndingsInPrefererredOrder(importMode);
+        const ending = allowedEndings[0];
         const relativePath = rootDirs && tryGetModuleNameFromRootDirs(rootDirs, moduleFileName, sourceDirectory, getCanonicalFileName, ending, compilerOptions) ||
-            removeExtensionAndIndexPostFix(ensurePathIsNonModuleName(getRelativePathFromDirectory(sourceDirectory, moduleFileName, getCanonicalFileName)), ending, compilerOptions);
+            processEnding(ensurePathIsNonModuleName(getRelativePathFromDirectory(sourceDirectory, moduleFileName, getCanonicalFileName)), ending, compilerOptions);
         if (!baseUrl && !paths || relativePreference === RelativePreference.Relative) {
             return relativePath;
         }
@@ -308,8 +342,8 @@ namespace ts.moduleSpecifiers {
             return relativePath;
         }
 
-        const fromPaths = paths && tryGetModuleNameFromPaths(relativeToBaseUrl, paths, getAllowedEndings(ending, compilerOptions, importMode), host, compilerOptions);
-        const nonRelative = fromPaths === undefined && baseUrl !== undefined ? removeExtensionAndIndexPostFix(relativeToBaseUrl, ending, compilerOptions) : fromPaths;
+        const fromPaths = paths && tryGetModuleNameFromPaths(relativeToBaseUrl, paths, allowedEndings, host, compilerOptions);
+        const nonRelative = fromPaths === undefined && baseUrl !== undefined ? processEnding(relativeToBaseUrl, ending, compilerOptions) : fromPaths;
         if (!nonRelative) {
             return relativePath;
         }
@@ -558,18 +592,6 @@ namespace ts.moduleSpecifiers {
         }
     }
 
-    function getAllowedEndings(preferredEnding: Ending, compilerOptions: CompilerOptions, importMode: SourceFile["impliedNodeFormat"]) {
-        if (getEmitModuleResolutionKind(compilerOptions) >= ModuleResolutionKind.Node16 && importMode === ModuleKind.ESNext) {
-            return [Ending.JsExtension];
-        }
-        switch (preferredEnding) {
-            case Ending.JsExtension: return [Ending.JsExtension, Ending.Minimal, Ending.Index];
-            case Ending.Index: return [Ending.Index, Ending.Minimal, Ending.JsExtension];
-            case Ending.Minimal: return [Ending.Minimal, Ending.Index, Ending.JsExtension];
-            default: Debug.assertNever(preferredEnding);
-        }
-    }
-
     function tryGetModuleNameFromPaths(relativeToBaseUrl: string, paths: MapLike<readonly string[]>, allowedEndings: Ending[], host: ModuleSpecifierResolutionHost, compilerOptions: CompilerOptions): string | undefined {
         for (const key in paths) {
             for (const patternText of paths[key]) {
@@ -613,7 +635,7 @@ namespace ts.moduleSpecifiers {
                 // sorted among the others for a particular value of `importModuleSpecifierEnding`.
                 const candidates: { ending: Ending | undefined, value: string }[] = allowedEndings.map(ending => ({
                     ending,
-                    value: removeExtensionAndIndexPostFix(relativeToBaseUrl, ending, compilerOptions)
+                    value: processEnding(relativeToBaseUrl, ending, compilerOptions)
                 }));
                 if (tryGetExtensionFromPath(pattern)) {
                     candidates.push({ ending: undefined, value: relativeToBaseUrl });
@@ -650,7 +672,7 @@ namespace ts.moduleSpecifiers {
             // `Ending.Index` result, which should already be in the list of candidates if `Minimal` was. (Note: the assumption here is
             // that every module resolution mode that supports dropping extensions also supports dropping `/index`. Like literally
             // everything else in this file, this logic needs to be updated if that's not true in some future module resolution mode.)
-            return ending !== Ending.Minimal || value === removeExtensionAndIndexPostFix(relativeToBaseUrl, ending, compilerOptions, host);
+            return ending !== Ending.Minimal || value === processEnding(relativeToBaseUrl, ending, compilerOptions, host);
         }
     }
 
@@ -733,13 +755,11 @@ namespace ts.moduleSpecifiers {
 
         const normalizedSourcePath = getPathRelativeToRootDirs(sourceDirectory, rootDirs, getCanonicalFileName);
         const relativePath = normalizedSourcePath !== undefined ? ensurePathIsNonModuleName(getRelativePathFromDirectory(normalizedSourcePath, normalizedTargetPath, getCanonicalFileName)) : normalizedTargetPath;
-        return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeJs
-            ? removeExtensionAndIndexPostFix(relativePath, ending, compilerOptions)
-            : removeFileExtension(relativePath);
+        return processEnding(relativePath, ending, compilerOptions);
     }
 
     function tryGetModuleNameAsNodeModule({ path, isRedirect }: ModulePath, { getCanonicalFileName, sourceDirectory }: Info, importingSourceFile: SourceFile , host: ModuleSpecifierResolutionHost, options: CompilerOptions, userPreferences: UserPreferences, packageNameOnly?: boolean, overrideMode?: ModuleKind.ESNext | ModuleKind.CommonJS): string | undefined {
-        if (!host.fileExists || !host.readFile) {
+        if (!host.fileExists || !host.readFile || getEmitModuleResolutionKind(options) === ModuleResolutionKind.Minimal) {
             return undefined;
         }
         const parts: NodeModulePathParts = getNodeModulePathParts(path)!;
@@ -750,6 +770,7 @@ namespace ts.moduleSpecifiers {
         // Simplify the full file path to something that can be resolved by Node.
 
         const preferences = getPreferences(host, userPreferences, options, importingSourceFile);
+        const allowedEndings = preferences.getAllowedEndingsInPrefererredOrder();
         let moduleSpecifier = path;
         let isPackageRootPath = false;
         if (!packageNameOnly) {
@@ -776,7 +797,7 @@ namespace ts.moduleSpecifiers {
                 // try with next level of directory
                 packageRootIndex = path.indexOf(directorySeparator, packageRootIndex + 1);
                 if (packageRootIndex === -1) {
-                    moduleSpecifier = removeExtensionAndIndexPostFix(moduleFileName, preferences.ending, options, host);
+                    moduleSpecifier = processEnding(moduleFileName, allowedEndings[0], options, host);
                     break;
                 }
             }
@@ -832,7 +853,7 @@ namespace ts.moduleSpecifiers {
                     const fromPaths = tryGetModuleNameFromPaths(
                         subModuleName,
                         versionPaths.paths,
-                        getAllowedEndings(preferences.ending, options, importMode),
+                        allowedEndings,
                         host,
                         options
                     );
@@ -889,7 +910,7 @@ namespace ts.moduleSpecifiers {
         });
     }
 
-    function removeExtensionAndIndexPostFix(fileName: string, ending: Ending, options: CompilerOptions, host?: ModuleSpecifierResolutionHost): string {
+    function processEnding(fileName: string, ending: Ending, options: CompilerOptions, host?: ModuleSpecifierResolutionHost): string {
         if (fileExtensionIsOneOf(fileName, [Extension.Json, Extension.Mjs, Extension.Cjs])) return fileName;
         const noExtension = removeFileExtension(fileName);
         if (fileName === noExtension) return fileName;
diff --git a/tests/baselines/reference/api/tsserverlibrary.d.ts b/tests/baselines/reference/api/tsserverlibrary.d.ts
index 936b189192bfe..ba647af4fc3eb 100644
--- a/tests/baselines/reference/api/tsserverlibrary.d.ts
+++ b/tests/baselines/reference/api/tsserverlibrary.d.ts
@@ -2993,6 +2993,7 @@ declare namespace ts {
     }
     export type CompilerOptionsValue = string | number | boolean | (string | number)[] | string[] | MapLike<string[]> | PluginImport[] | ProjectReference[] | null | undefined;
     export interface CompilerOptions {
+        allowImportingTsExtensions?: boolean;
         allowJs?: boolean;
         allowSyntheticDefaultImports?: boolean;
         allowUmdGlobalAccess?: boolean;
@@ -5059,7 +5060,7 @@ declare namespace ts {
     export function classicNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: NonRelativeModuleNameResolutionCache, redirectedReference?: ResolvedProjectReference): ResolvedModuleWithFailedLookupLocations;
     export function minimalModuleNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations;
     export function shouldResolveTsExtension(compilerOptions: CompilerOptions): boolean;
-    export function shouldAllowTsExtension(compilerOptions: CompilerOptions): boolean;
+    export function shouldAllowImportingTsExtension(compilerOptions: CompilerOptions, fromFileName?: string): boolean | "" | undefined;
     export {};
 }
 declare namespace ts {
diff --git a/tests/baselines/reference/api/typescript.d.ts b/tests/baselines/reference/api/typescript.d.ts
index 5f0a608c6962c..cf28270b66367 100644
--- a/tests/baselines/reference/api/typescript.d.ts
+++ b/tests/baselines/reference/api/typescript.d.ts
@@ -2993,6 +2993,7 @@ declare namespace ts {
     }
     export type CompilerOptionsValue = string | number | boolean | (string | number)[] | string[] | MapLike<string[]> | PluginImport[] | ProjectReference[] | null | undefined;
     export interface CompilerOptions {
+        allowImportingTsExtensions?: boolean;
         allowJs?: boolean;
         allowSyntheticDefaultImports?: boolean;
         allowUmdGlobalAccess?: boolean;
@@ -5059,7 +5060,7 @@ declare namespace ts {
     export function classicNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost, cache?: NonRelativeModuleNameResolutionCache, redirectedReference?: ResolvedProjectReference): ResolvedModuleWithFailedLookupLocations;
     export function minimalModuleNameResolver(moduleName: string, containingFile: string, compilerOptions: CompilerOptions, host: ModuleResolutionHost): ResolvedModuleWithFailedLookupLocations;
     export function shouldResolveTsExtension(compilerOptions: CompilerOptions): boolean;
-    export function shouldAllowTsExtension(compilerOptions: CompilerOptions): boolean;
+    export function shouldAllowImportingTsExtension(compilerOptions: CompilerOptions, fromFileName?: string): boolean | "" | undefined;
     export {};
 }
 declare namespace ts {
diff --git a/tests/baselines/reference/showConfig/Shows tsconfig for single option/allowImportingTsExtensions/tsconfig.json b/tests/baselines/reference/showConfig/Shows tsconfig for single option/allowImportingTsExtensions/tsconfig.json
new file mode 100644
index 0000000000000..88c95f9eb8307
--- /dev/null
+++ b/tests/baselines/reference/showConfig/Shows tsconfig for single option/allowImportingTsExtensions/tsconfig.json	
@@ -0,0 +1,5 @@
+{
+    "compilerOptions": {
+        "allowImportingTsExtensions": true
+    }
+}
diff --git a/tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json b/tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json
index 75dcaeac2e2b9..5cad175ba34fa 100644
--- a/tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Default initialized TSConfig/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with --help/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with --help/tsconfig.json
index 75dcaeac2e2b9..5cad175ba34fa 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with --help/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with --help/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with --watch/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with --watch/tsconfig.json
index 75dcaeac2e2b9..5cad175ba34fa 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with --watch/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with --watch/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json
index ce36f2a0fcfd7..e1b9e67e7b66d 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with advanced options/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json
index a4be57dd3410e..cc29170683efb 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with boolean value compiler options/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json
index faa350ae98575..0b6e055e0a2cd 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with enum value compiler options/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json
index 09587994ffbcd..01830a8f79b49 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with files options/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json
index abb2dfd47088b..6798430ea05ee 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option value/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json
index 75dcaeac2e2b9..5cad175ba34fa 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with incorrect compiler option/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json
index 04aa9196bfc65..6bae69884ebdb 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options with enum value/tsconfig.json	
@@ -35,6 +35,7 @@
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json b/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json
index 4eb9bb8aa4b84..c6de1fdcc3575 100644
--- a/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json	
+++ b/tests/baselines/reference/tsConfig/Initialized TSConfig with list compiler options/tsconfig.json	
@@ -35,6 +35,7 @@
     "types": ["jquery","mocha"],                         /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/declarationDir-is-specified.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/declarationDir-is-specified.js
index 2cf43a8189e28..782dc8bc57911 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/declarationDir-is-specified.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/declarationDir-is-specified.js
@@ -56,6 +56,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-and-declarationDir-is-specified.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-and-declarationDir-is-specified.js
index 0bdc2d356c5e3..54e482fe2570b 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-and-declarationDir-is-specified.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-and-declarationDir-is-specified.js
@@ -56,6 +56,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-is-specified.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-is-specified.js
index 673a8e6669886..5b88985795b6e 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-is-specified.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/when-outDir-is-specified.js
@@ -56,6 +56,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/with-outFile.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/with-outFile.js
index 83e6548b002fb..482495d68b2c7 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/with-outFile.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/with-outFile.js
@@ -56,6 +56,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified-with-declaration-enabled.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified-with-declaration-enabled.js
index c87baf238012c..a80a8e8c3c89e 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified-with-declaration-enabled.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified-with-declaration-enabled.js
@@ -56,6 +56,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 
diff --git a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified.js b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified.js
index 82310b617cd3d..b1b8e8a3eaedf 100644
--- a/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified.js
+++ b/tests/baselines/reference/tscWatch/programUpdates/should-not-trigger-recompilation-because-of-program-emit/without-outDir-or-outFile-is-specified.js
@@ -56,6 +56,7 @@ interface Array<T> { length: number; [n: number]: T; }
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
     // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
     // "moduleSuffixes": [],                             /* List of file name suffixes to search when resolving a module. */
+    // "allowImportingTsExtensions": true,               /* Allow imports to include TypeScript file extensions. Requires '--moduleResolution minimal' and either '--noEmit' or '--emitDeclarationOnly' to be set. */
     // "resolveJsonModule": true,                        /* Enable importing .json files. */
     // "noResolve": true,                                /* Disallow 'import's, 'require's or '<reference>'s from expanding the number of files TypeScript should add to a project. */
 

From 458c12596f10e3f0d347c14b7b89bd61f114a1ab Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Mon, 19 Sep 2022 11:11:20 -0700
Subject: [PATCH 08/14] Add auto-import tests

---
 src/compiler/moduleSpecifiers.ts             | 18 ++++--
 src/harness/fourslashImpl.ts                 | 64 +++++++++++++++++---
 src/harness/fourslashInterfaceImpl.ts        |  4 ++
 src/services/utilities.ts                    |  3 +-
 tests/cases/fourslash/autoImportsMinimal1.ts | 17 ++++++
 tests/cases/fourslash/autoImportsMinimal2.ts | 19 ++++++
 tests/cases/fourslash/fourslash.ts           |  1 +
 7 files changed, 113 insertions(+), 13 deletions(-)
 create mode 100644 tests/cases/fourslash/autoImportsMinimal1.ts
 create mode 100644 tests/cases/fourslash/autoImportsMinimal2.ts

diff --git a/src/compiler/moduleSpecifiers.ts b/src/compiler/moduleSpecifiers.ts
index 1f560927e3e55..119a55565f34d 100644
--- a/src/compiler/moduleSpecifiers.ts
+++ b/src/compiler/moduleSpecifiers.ts
@@ -3,7 +3,7 @@
 namespace ts.moduleSpecifiers {
     const enum RelativePreference { Relative, NonRelative, Shortest, ExternalNonRelative }
     // See UserPreferences#importPathEnding
-    const enum Ending { Minimal, Index, JsExtension }
+    const enum Ending { Minimal, Index, JsExtension, TsExtension }
 
     // Processed preferences
     interface Preferences {
@@ -36,6 +36,9 @@ namespace ts.moduleSpecifiers {
                     getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Minimal ||
                     isFormatRequiringExtensions()
                 ) {
+                    if (shouldAllowImportingTsExtension(compilerOptions, importingSourceFile.fileName)) {
+                        return [Ending.TsExtension, Ending.JsExtension];
+                    }
                     return [Ending.JsExtension];
                 }
                 if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Classic) {
@@ -43,6 +46,7 @@ namespace ts.moduleSpecifiers {
                 }
                 switch (preferredEnding) {
                     case Ending.JsExtension: return [Ending.JsExtension, Ending.Minimal, Ending.Index];
+                    case Ending.TsExtension: return [Ending.TsExtension, Ending.TsExtension, Ending.Minimal, Ending.Index];
                     case Ending.Index: return [Ending.Index, Ending.Minimal, Ending.JsExtension];
                     case Ending.Minimal: return [Ending.Minimal, Ending.Index, Ending.JsExtension];
                     default: Debug.assertNever(preferredEnding);
@@ -58,8 +62,10 @@ namespace ts.moduleSpecifiers {
             switch (importModuleSpecifierEnding) {
                 case "minimal": return Ending.Minimal;
                 case "index": return Ending.Index;
-                case "js": return Ending.JsExtension;
-                default: return usesJsExtensionOnImports(importingSourceFile) ? Ending.JsExtension : Ending.Minimal;
+                case "js": return shouldAllowImportingTsExtension(compilerOptions) ? Ending.TsExtension : Ending.JsExtension;
+                default: return usesExtensionsOnImports(importingSourceFile)
+                    ? shouldAllowImportingTsExtension(compilerOptions) ? Ending.TsExtension : Ending.JsExtension
+                    : Ending.Minimal;
             }
         }
 
@@ -403,8 +409,8 @@ namespace ts.moduleSpecifiers {
         return count;
     }
 
-    function usesJsExtensionOnImports({ imports }: SourceFile): boolean {
-        return firstDefined(imports, ({ text }) => pathIsRelative(text) ? hasJSFileExtension(text) : undefined) || false;
+    function usesExtensionsOnImports({ imports }: SourceFile): boolean {
+        return firstDefined(imports, ({ text }) => pathIsRelative(text) ? (hasJSFileExtension(text) || hasTSFileExtension(text)) : undefined) || false;
     }
 
     function comparePathsByRedirectAndNumberOfDirectorySeparators(a: ModulePath, b: ModulePath) {
@@ -928,6 +934,8 @@ namespace ts.moduleSpecifiers {
                 return noExtension;
             case Ending.JsExtension:
                 return noExtension + getJSExtensionForFile(fileName, options);
+            case Ending.TsExtension:
+                return fileName;
             default:
                 return Debug.assertNever(ending);
         }
diff --git a/src/harness/fourslashImpl.ts b/src/harness/fourslashImpl.ts
index 46d2bc242e772..6883a6d25c554 100644
--- a/src/harness/fourslashImpl.ts
+++ b/src/harness/fourslashImpl.ts
@@ -798,16 +798,20 @@ namespace FourSlash {
             });
         }
 
-        private renderMarkers(markers: { text: string, fileName: string, position: number }[]) {
+        private renderMarkers(markers: { text: string, fileName: string, position: number }[], useTerminalBoldSequence = true) {
             const filesToDisplay = ts.deduplicate(markers.map(m => m.fileName), ts.equateValues);
             return filesToDisplay.map(fileName => {
                 const markersToRender = markers.filter(m => m.fileName === fileName).sort((a, b) => b.position - a.position);
                 let fileContent = this.tryGetFileContent(fileName) || "";
                 for (const marker of markersToRender) {
-                    fileContent = fileContent.slice(0, marker.position) + `\x1b[1;4m/*${marker.text}*/\x1b[0;31m` + fileContent.slice(marker.position);
+                    fileContent = fileContent.slice(0, marker.position) + bold(`/*${marker.text}*/`) + fileContent.slice(marker.position);
                 }
                 return `// @Filename: ${fileName}\n${fileContent}`;
             }).join("\n\n");
+
+            function bold(text: string) {
+                return useTerminalBoldSequence ? `\x1b[1;4m${text}\x1b[0;31m` : text;
+            }
         }
 
         private verifyDefinitionTextSpan(defs: ts.DefinitionInfoAndBoundSpan, startMarkerName: string) {
@@ -3127,6 +3131,48 @@ namespace FourSlash {
             assert.deepEqual(actualModuleSpecifiers, moduleSpecifiers);
         }
 
+        public baselineAutoImports(markerName: string, preferences?: ts.UserPreferences) {
+            const marker = this.getMarkerByName(markerName);
+            const baselineFile = this.getBaselineFileNameForContainingTestFile(`.baseline.md`);
+            const completionPreferences = {
+                includeCompletionsForModuleExports: true,
+                includeCompletionsWithInsertText: true,
+                allowIncompleteCompletions: true,
+                includeCompletionsWithSnippetText: true,
+                ...preferences
+            };
+
+            const ext = ts.getAnyExtensionFromPath(this.activeFile.fileName).slice(1);
+            const lang = ["mts", "cts"].includes(ext) ? "ts" : ext;
+            let baselineText = codeFence(this.renderMarkers([{ text: "|", fileName: marker.fileName, position: marker.position }], /*useTerminalBoldSequence*/ false), lang) + "\n\n";
+            this.goToMarker(marker);
+
+            const completions = this.getCompletionListAtCaret(completionPreferences)!;
+
+            const autoImportCompletions = completions.entries.filter(c => c.hasAction && c.source && c.sortText === ts.Completions.SortText.AutoImportSuggestions);
+            if (autoImportCompletions.length) {
+                baselineText += `## From completions\n\n${autoImportCompletions.map(c => `- \`${c.name}\` from \`"${c.source}"\``).join("\n")}\n\n`;
+                autoImportCompletions.forEach(c => {
+                    const details = this.getCompletionEntryDetails(c.name, c.source, c.data, completionPreferences);
+                    assert(details?.codeActions, `Entry '${c.name}' from "${c.source}" returned no code actions from completion details request`);
+                    assert(details.codeActions.length === 1, `Entry '${c.name}' from "${c.source}" returned more than one code action`);
+                    assert(details.codeActions[0].changes.length === 1, `Entry '${c.name}' from "${c.source}" returned a code action changing more than one file`);
+                    assert(details.codeActions[0].changes[0].fileName === this.activeFile.fileName, `Entry '${c.name}' from "${c.source}" returned a code action changing a different file`);
+                    const changes = details.codeActions[0].changes[0].textChanges;
+                    const completionChange: ts.TextChange = { newText: c.insertText || c.name, span: c.replacementSpan || completions.optionalReplacementSpan || { start: marker.position, length: 0 } };
+                    const sortedChanges = [...changes, completionChange].sort((a, b) => a.span.start - b.span.start);
+                    let newFileContent = this.activeFile.content;
+                    for (let i = sortedChanges.length - 1; i >= 0; i--) {
+                        newFileContent = newFileContent.substring(0, sortedChanges[i].span.start) + sortedChanges[i].newText + newFileContent.substring(sortedChanges[i].span.start + sortedChanges[i].span.length);
+                    }
+                    baselineText += codeFence(newFileContent, lang) + "\n\n";
+                });
+            }
+
+            // TODO: do codefixes too
+            Harness.Baseline.runBaseline(baselineFile, baselineText);
+        }
+
         public verifyDocCommentTemplate(expected: ts.TextInsertion | undefined, options?: ts.DocCommentTemplateOptions) {
             const name = "verifyDocCommentTemplate";
             const actual = this.languageService.getDocCommentTemplateAtPosition(this.activeFile.fileName, this.currentCaretPosition, options || { generateReturnInDocTemplate: true })!;
@@ -4598,10 +4644,10 @@ namespace FourSlash {
         }
 
         return ranges;
-      }
+    }
 
-      // Adds an _ when the source string and the target string have a whitespace difference
-      function highlightDifferenceBetweenStrings(source: string, target: string) {
+    // Adds an _ when the source string and the target string have a whitespace difference
+    function highlightDifferenceBetweenStrings(source: string, target: string) {
         const ranges = rangesOfDiffBetweenTwoStrings(source, target);
         let emTarget = target;
         ranges.forEach((range, index) => {
@@ -4613,9 +4659,13 @@ namespace FourSlash {
                 range.start + 1 + additionalOffset,
                 range.start + range.length + 1 + additionalOffset
             );
-             const after = emTarget.slice(range.start + range.length + 1 + additionalOffset, emTarget.length);
+            const after = emTarget.slice(range.start + range.length + 1 + additionalOffset, emTarget.length);
             emTarget = before + lhs + between + rhs + after;
         });
         return emTarget;
-      }
+    }
+
+    function codeFence(code: string, lang?: string) {
+        return `\`\`\`${lang || ""}\n${code}\n\`\`\``;
+    }
 }
diff --git a/src/harness/fourslashInterfaceImpl.ts b/src/harness/fourslashInterfaceImpl.ts
index 4112072d38835..5065b5dba5bc1 100644
--- a/src/harness/fourslashInterfaceImpl.ts
+++ b/src/harness/fourslashInterfaceImpl.ts
@@ -486,6 +486,10 @@ namespace FourSlashInterface {
             this.state.verifyImportFixModuleSpecifiers(marker, moduleSpecifiers, preferences);
         }
 
+        public baselineAutoImports(marker: string, preferences?: ts.UserPreferences) {
+            this.state.baselineAutoImports(marker, preferences);
+        }
+
         public navigationBar(json: any, options?: { checkSpans?: boolean }) {
             this.state.verifyNavigationBar(json, options);
         }
diff --git a/src/services/utilities.ts b/src/services/utilities.ts
index 4d24e57d051ee..b021cd350d563 100644
--- a/src/services/utilities.ts
+++ b/src/services/utilities.ts
@@ -1909,8 +1909,9 @@ namespace ts {
     export function programContainsEsModules(program: Program): boolean {
         return program.getSourceFiles().some(s => !s.isDeclarationFile && !program.isSourceFileFromExternalLibrary(s) && !!s.externalModuleIndicator);
     }
+    // TODO: this function is, at best, poorly named. Use sites are pretty suspicious.
     export function compilerOptionsIndicateEsModules(compilerOptions: CompilerOptions): boolean {
-        return !!compilerOptions.module || getEmitScriptTarget(compilerOptions) >= ScriptTarget.ES2015 || !!compilerOptions.noEmit;
+        return !!compilerOptions.module || getEmitScriptTarget(compilerOptions) >= ScriptTarget.ES2015 || !!compilerOptions.noEmit || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Minimal;
     }
 
     export function createModuleSpecifierResolutionHost(program: Program, host: LanguageServiceHost): ModuleSpecifierResolutionHost {
diff --git a/tests/cases/fourslash/autoImportsMinimal1.ts b/tests/cases/fourslash/autoImportsMinimal1.ts
new file mode 100644
index 0000000000000..175f731e3abf8
--- /dev/null
+++ b/tests/cases/fourslash/autoImportsMinimal1.ts
@@ -0,0 +1,17 @@
+/// <reference path="fourslash.ts" />
+
+// @moduleResolution: minimal
+
+// @Filename: /node_modules/@types/foo/index.d.ts
+//// export const fromAtTypesFoo: number;
+
+// @Filename: /node_modules/bar/index.d.ts
+//// export const fromBar: number;
+
+// @Filename: /local.ts
+//// export const fromLocal: number;
+
+// @Filename: /main.ts
+//// /**/
+
+verify.baselineAutoImports("");
diff --git a/tests/cases/fourslash/autoImportsMinimal2.ts b/tests/cases/fourslash/autoImportsMinimal2.ts
new file mode 100644
index 0000000000000..3ab44e1c00da4
--- /dev/null
+++ b/tests/cases/fourslash/autoImportsMinimal2.ts
@@ -0,0 +1,19 @@
+/// <reference path="fourslash.ts" />
+
+// @moduleResolution: minimal
+// @allowImportingTsExtensions: true
+// @noEmit: true
+
+// @Filename: /node_modules/@types/foo/index.d.ts
+//// export const fromAtTypesFoo: number;
+
+// @Filename: /node_modules/bar/index.d.ts
+//// export const fromBar: number;
+
+// @Filename: /local.ts
+//// export const fromLocal: number;
+
+// @Filename: /main.ts
+//// /**/
+
+verify.baselineAutoImports("");
diff --git a/tests/cases/fourslash/fourslash.ts b/tests/cases/fourslash/fourslash.ts
index 76ca5d33314d7..058632b616992 100644
--- a/tests/cases/fourslash/fourslash.ts
+++ b/tests/cases/fourslash/fourslash.ts
@@ -370,6 +370,7 @@ declare namespace FourSlashInterface {
         getAndApplyCodeFix(errorCode?: number, index?: number): void;
         importFixAtPosition(expectedTextArray: string[], errorCode?: number, options?: UserPreferences): void;
         importFixModuleSpecifiers(marker: string, moduleSpecifiers: string[], options?: UserPreferences): void;
+        baselineAutoImports(marker: string, options?: UserPreferences): void;
 
         navigationBar(json: any, options?: { checkSpans?: boolean }): void;
         navigationTree(json: any, options?: { checkSpans?: boolean }): void;

From 7d64928117dbad08fa63888118d7b5cbcde9cde4 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Mon, 26 Sep 2022 10:55:33 -0700
Subject: [PATCH 09/14] Disallow relative imports into node_modules

---
 src/compiler/checker.ts                       |  5 +++-
 src/compiler/diagnosticMessages.json          |  4 +++
 src/compiler/moduleNameResolver.ts            | 13 ++++++++++
 .../reference/minimal_nodeModules.errors.txt  | 26 +++++++++++++++++++
 .../reference/minimal_nodeModules.js          | 21 +++++++++++++++
 .../reference/minimal_nodeModules.symbols     | 16 ++++++++++++
 .../reference/minimal_nodeModules.types       | 16 ++++++++++++
 .../moduleResolution/minimal_nodeModules.ts   | 16 ++++++++++++
 8 files changed, 116 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/minimal_nodeModules.errors.txt
 create mode 100644 tests/baselines/reference/minimal_nodeModules.js
 create mode 100644 tests/baselines/reference/minimal_nodeModules.symbols
 create mode 100644 tests/baselines/reference/minimal_nodeModules.types
 create mode 100644 tests/cases/conformance/moduleResolution/minimal_nodeModules.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 36e21f63f35d5..e9d5b3229213f 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3740,7 +3740,10 @@ namespace ts {
                     const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions);
                     const resolutionIsNode16OrNext = moduleResolutionKind === ModuleResolutionKind.Node16 ||
                         moduleResolutionKind === ModuleResolutionKind.NodeNext;
-                    if (tsExtension) {
+                    if (moduleResolutionKind === ModuleResolutionKind.Minimal && pathContainsNodeModules(moduleReference)) {
+                        error(errorNode, Diagnostics.Relative_imports_into_node_modules_are_not_allowed);
+                    }
+                    else if (tsExtension) {
                         errorOnTSExtensionImport(tsExtension);
                     }
                     else if (!compilerOptions.resolveJsonModule &&
diff --git a/src/compiler/diagnosticMessages.json b/src/compiler/diagnosticMessages.json
index c6614d6482b14..97238efc34650 100644
--- a/src/compiler/diagnosticMessages.json
+++ b/src/compiler/diagnosticMessages.json
@@ -3571,6 +3571,10 @@
         "category": "Error",
         "code": 2845
     },
+    "Relative imports into 'node_modules' are not allowed.": {
+        "category": "Error",
+        "code": 2846
+    },
 
     "Import declaration '{0}' is using private name '{1}'.": {
         "category": "Error",
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index 6fc614ab5dc1a..7aa263db0a893 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -2705,6 +2705,19 @@ namespace ts {
             if (resolvedUsingSettings) {
                 return resolvedUsingSettings;
             }
+            if (isExternalModuleNameRelative(moduleName) && pathContainsNodeModules(moduleName)) {
+                // A relative import into node_modules is a problem for a few reasons:
+                //   1. Portability - if the code gets published as a library, it will very likely break
+                //   2. It's unclear how we should resolve types. By typical relative import rules, we
+                //      would ignore package.json fields that tell us where to find types and would have
+                //      no special behavior linking up node_modules/@types with their implementations -
+                //      we would only find .d.ts files as siblings of .js files. Any package that puts
+                //      their types in a separate directory, or is typed by @types, would be broken.
+                //      Some of these redirections would be safe to do, but others might reflect
+                //      Node-specific resolution features that would only work with non-relative imports.
+                // There's a diagnostic issued for this case in the checker.
+                return noPackageId(/*resolved*/ undefined);
+            }
             const resolvedRelative = loadModuleFromFileNoImplicitExtensions(extensions, candidate, /*onlyRecordFailures*/ false, state);
             if (resolvedRelative) {
                 return noPackageId(resolvedRelative);
diff --git a/tests/baselines/reference/minimal_nodeModules.errors.txt b/tests/baselines/reference/minimal_nodeModules.errors.txt
new file mode 100644
index 0000000000000..1f114980ccf67
--- /dev/null
+++ b/tests/baselines/reference/minimal_nodeModules.errors.txt
@@ -0,0 +1,26 @@
+/main.ts(1,16): error TS2307: Cannot find module 'foo' or its corresponding type declarations.
+/main.ts(2,16): error TS2846: Relative imports into 'node_modules' are not allowed.
+/main.ts(3,21): error TS2846: Relative imports into 'node_modules' are not allowed.
+
+
+==== /node_modules/foo/index.d.ts (0 errors) ====
+    import {} from "./other.js";
+    export {};
+    
+==== /node_modules/foo/other.d.ts (0 errors) ====
+    export {};
+    
+==== /node_modules/@types/foo/index.d.ts (0 errors) ====
+    export {};
+    
+==== /main.ts (3 errors) ====
+    import {} from "foo";
+                   ~~~~~
+!!! error TS2307: Cannot find module 'foo' or its corresponding type declarations.
+    import {} from "./node_modules/foo/index.js";
+                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2846: Relative imports into 'node_modules' are not allowed.
+    import type {} from "./node_modules/@types/foo/index.d.ts";
+                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+!!! error TS2846: Relative imports into 'node_modules' are not allowed.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_nodeModules.js b/tests/baselines/reference/minimal_nodeModules.js
new file mode 100644
index 0000000000000..25b341dfcd7e8
--- /dev/null
+++ b/tests/baselines/reference/minimal_nodeModules.js
@@ -0,0 +1,21 @@
+//// [tests/cases/conformance/moduleResolution/minimal_nodeModules.ts] ////
+
+//// [index.d.ts]
+import {} from "./other.js";
+export {};
+
+//// [other.d.ts]
+export {};
+
+//// [index.d.ts]
+export {};
+
+//// [main.ts]
+import {} from "foo";
+import {} from "./node_modules/foo/index.js";
+import type {} from "./node_modules/@types/foo/index.d.ts";
+
+
+//// [main.js]
+"use strict";
+exports.__esModule = true;
diff --git a/tests/baselines/reference/minimal_nodeModules.symbols b/tests/baselines/reference/minimal_nodeModules.symbols
new file mode 100644
index 0000000000000..584f016b4b220
--- /dev/null
+++ b/tests/baselines/reference/minimal_nodeModules.symbols
@@ -0,0 +1,16 @@
+=== /node_modules/foo/index.d.ts ===
+import {} from "./other.js";
+No type information for this code.export {};
+No type information for this code.
+No type information for this code.=== /node_modules/foo/other.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /node_modules/@types/foo/index.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /main.ts ===
+import {} from "foo";
+No type information for this code.import {} from "./node_modules/foo/index.js";
+No type information for this code.import type {} from "./node_modules/@types/foo/index.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_nodeModules.types b/tests/baselines/reference/minimal_nodeModules.types
new file mode 100644
index 0000000000000..584f016b4b220
--- /dev/null
+++ b/tests/baselines/reference/minimal_nodeModules.types
@@ -0,0 +1,16 @@
+=== /node_modules/foo/index.d.ts ===
+import {} from "./other.js";
+No type information for this code.export {};
+No type information for this code.
+No type information for this code.=== /node_modules/foo/other.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /node_modules/@types/foo/index.d.ts ===
+export {};
+No type information for this code.
+No type information for this code.=== /main.ts ===
+import {} from "foo";
+No type information for this code.import {} from "./node_modules/foo/index.js";
+No type information for this code.import type {} from "./node_modules/@types/foo/index.d.ts";
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/cases/conformance/moduleResolution/minimal_nodeModules.ts b/tests/cases/conformance/moduleResolution/minimal_nodeModules.ts
new file mode 100644
index 0000000000000..1ddb7f9153345
--- /dev/null
+++ b/tests/cases/conformance/moduleResolution/minimal_nodeModules.ts
@@ -0,0 +1,16 @@
+// @moduleResolution: minimal
+
+// @Filename: /node_modules/foo/index.d.ts
+import {} from "./other.js";
+export {};
+
+// @Filename: /node_modules/foo/other.d.ts
+export {};
+
+// @Filename: /node_modules/@types/foo/index.d.ts
+export {};
+
+// @Filename: /main.ts
+import {} from "foo";
+import {} from "./node_modules/foo/index.js";
+import type {} from "./node_modules/@types/foo/index.d.ts";

From 0249e0a93e08a4365764a0ff92b2b0dfd0daacc0 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Mon, 26 Sep 2022 11:35:55 -0700
Subject: [PATCH 10/14] =?UTF-8?q?Ensure=20auto-imports=20don=E2=80=99t=20s?=
 =?UTF-8?q?uggest=20./node=5Fmodules;?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/compiler/checker.ts                       | 23 +++++++++++++++----
 src/compiler/moduleNameResolver.ts            | 13 -----------
 src/services/codefixes/importFixes.ts         |  3 ++-
 src/services/completions.ts                   | 11 ++++++---
 .../reference/autoImportsMinimal1.baseline.md | 15 ++++++++++++
 .../reference/autoImportsMinimal2.baseline.md | 15 ++++++++++++
 6 files changed, 59 insertions(+), 21 deletions(-)
 create mode 100644 tests/baselines/reference/autoImportsMinimal1.baseline.md
 create mode 100644 tests/baselines/reference/autoImportsMinimal2.baseline.md

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index e9d5b3229213f..afc8129b4322a 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3598,6 +3598,7 @@ namespace ts {
                     (isModuleDeclaration(location) ? location : location.parent && isModuleDeclaration(location.parent) && location.parent.name === location ? location.parent : undefined)?.name ||
                     (isLiteralImportTypeNode(location) ? location : undefined)?.argument.literal;
             const mode = contextSpecifier && isStringLiteralLike(contextSpecifier) ? getModeForUsageLocation(currentSourceFile, contextSpecifier) : currentSourceFile.impliedNodeFormat;
+            const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions);
             const resolvedModule = getResolvedModule(currentSourceFile, moduleReference, mode);
             const resolutionDiagnostic = resolvedModule && getResolutionDiagnostic(compilerOptions, resolvedModule);
             const sourceFile = resolvedModule
@@ -3609,7 +3610,22 @@ namespace ts {
                     error(errorNode, resolutionDiagnostic, moduleReference, resolvedModule.resolvedFileName);
                 }
 
-                if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) {
+                if (moduleResolutionKind === ModuleResolutionKind.Minimal && pathContainsNodeModules(moduleReference)) {
+                    // A relative import into node_modules is a problem for a few reasons:
+                    //   1. Portability - if the code gets published as a library, it will very likely break
+                    //   2. It's unclear how we should resolve types. By typical relative import rules, we
+                    //      would ignore package.json fields that tell us where to find types and would have
+                    //      no special behavior linking up node_modules/@types with their implementations -
+                    //      we would only find .d.ts files as siblings of .js files. Any package that puts
+                    //      their types in a separate directory, or is typed by @types, would be broken.
+                    //      Some of these redirections would be safe to do, but others might reflect
+                    //      Node-specific resolution features that would only work with non-relative imports.
+                    // The module resolver still returns a result, because it's possible for a module in
+                    // node_modules to end up in the program, and module specifier generation assumes that it
+                    // is always possible to generate a module specifier, even if it also generates a diagnostic.
+                    error(errorNode, Diagnostics.Relative_imports_into_node_modules_are_not_allowed);
+                }
+                else if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) {
                     const importOrExport =
                         findAncestor(location, isImportDeclaration)?.importClause ||
                         findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)) as ImportEqualsDeclaration | ExportDeclaration | undefined;
@@ -3629,7 +3645,7 @@ namespace ts {
                     if (resolvedModule.isExternalLibraryImport && !resolutionExtensionIsTSOrJson(resolvedModule.extension)) {
                         errorOnImplicitAnyModule(/*isError*/ false, errorNode, resolvedModule, moduleReference);
                     }
-                    if (getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 || getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext) {
+                    if (moduleResolutionKind === ModuleResolutionKind.Node16 || moduleResolutionKind === ModuleResolutionKind.NodeNext) {
                         const isSyncImport = (currentSourceFile.impliedNodeFormat === ModuleKind.CommonJS && !findAncestor(location, isImportCall)) || !!findAncestor(location, isImportEqualsDeclaration);
                         const overrideClauseHost = findAncestor(location, l => isImportTypeNode(l) || isExportDeclaration(l) || isImportDeclaration(l)) as ImportTypeNode | ImportDeclaration | ExportDeclaration | undefined;
                         const overrideClause = overrideClauseHost && isImportTypeNode(overrideClauseHost) ? overrideClauseHost.assertions?.assertClause : overrideClauseHost?.assertClause;
@@ -3737,7 +3753,6 @@ namespace ts {
                 else {
                     const tsExtension = tryExtractTSExtension(moduleReference);
                     const isExtensionlessRelativePathImport = pathIsRelative(moduleReference) && !hasExtension(moduleReference);
-                    const moduleResolutionKind = getEmitModuleResolutionKind(compilerOptions);
                     const resolutionIsNode16OrNext = moduleResolutionKind === ModuleResolutionKind.Node16 ||
                         moduleResolutionKind === ModuleResolutionKind.NodeNext;
                     if (moduleResolutionKind === ModuleResolutionKind.Minimal && pathContainsNodeModules(moduleReference)) {
@@ -3748,7 +3763,7 @@ namespace ts {
                     }
                     else if (!compilerOptions.resolveJsonModule &&
                         fileExtensionIs(moduleReference, Extension.Json) &&
-                        getEmitModuleResolutionKind(compilerOptions) !== ModuleResolutionKind.Classic &&
+                        moduleResolutionKind !== ModuleResolutionKind.Classic &&
                         hasJsonModuleEmitEnabled(compilerOptions)) {
                         error(errorNode, Diagnostics.Cannot_find_module_0_Consider_using_resolveJsonModule_to_import_module_with_json_extension, moduleReference);
                     }
diff --git a/src/compiler/moduleNameResolver.ts b/src/compiler/moduleNameResolver.ts
index 7aa263db0a893..6fc614ab5dc1a 100644
--- a/src/compiler/moduleNameResolver.ts
+++ b/src/compiler/moduleNameResolver.ts
@@ -2705,19 +2705,6 @@ namespace ts {
             if (resolvedUsingSettings) {
                 return resolvedUsingSettings;
             }
-            if (isExternalModuleNameRelative(moduleName) && pathContainsNodeModules(moduleName)) {
-                // A relative import into node_modules is a problem for a few reasons:
-                //   1. Portability - if the code gets published as a library, it will very likely break
-                //   2. It's unclear how we should resolve types. By typical relative import rules, we
-                //      would ignore package.json fields that tell us where to find types and would have
-                //      no special behavior linking up node_modules/@types with their implementations -
-                //      we would only find .d.ts files as siblings of .js files. Any package that puts
-                //      their types in a separate directory, or is typed by @types, would be broken.
-                //      Some of these redirections would be safe to do, but others might reflect
-                //      Node-specific resolution features that would only work with non-relative imports.
-                // There's a diagnostic issued for this case in the checker.
-                return noPackageId(/*resolved*/ undefined);
-            }
             const resolvedRelative = loadModuleFromFileNoImplicitExtensions(extensions, candidate, /*onlyRecordFailures*/ false, state);
             if (resolvedRelative) {
                 return noPackageId(resolvedRelative);
diff --git a/src/services/codefixes/importFixes.ts b/src/services/codefixes/importFixes.ts
index 496a5d888a194..11e9d13f8bdf0 100644
--- a/src/services/codefixes/importFixes.ts
+++ b/src/services/codefixes/importFixes.ts
@@ -662,7 +662,8 @@ namespace ts.codefix {
         const compilerOptions = program.getCompilerOptions();
         const moduleSpecifierResolutionHost = createModuleSpecifierResolutionHost(program, host);
         const getChecker = createGetChecker(program, host);
-        const rejectNodeModulesRelativePaths = moduleResolutionUsesNodeModules(getEmitModuleResolutionKind(compilerOptions));
+        const moduleResolution = getEmitModuleResolutionKind(compilerOptions);
+        const rejectNodeModulesRelativePaths = moduleResolutionUsesNodeModules(moduleResolution) || moduleResolution === ModuleResolutionKind.Minimal;
         const getModuleSpecifiers = fromCacheOnly
             ? (moduleSymbol: Symbol) => ({ moduleSpecifiers: moduleSpecifiers.tryGetModuleSpecifiersFromCache(moduleSymbol, sourceFile, moduleSpecifierResolutionHost, preferences), computedWithoutCache: false })
             : (moduleSymbol: Symbol, checker: TypeChecker) => moduleSpecifiers.getModuleSpecifiersWithCacheInfo(moduleSymbol, checker, compilerOptions, sourceFile, moduleSpecifierResolutionHost, preferences);
diff --git a/src/services/completions.ts b/src/services/completions.ts
index 48e1c28bf01de..439e674f88252 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -169,7 +169,7 @@ namespace ts.Completions {
 
     const enum GlobalsSearch { Continue, Success, Fail }
 
-    interface ModuleSpecifierResolutioContext {
+    interface ModuleSpecifierResolutionContext {
         tryResolve: (exportInfo: readonly SymbolExportInfo[], symbolName: string, isFromAmbientModule: boolean) => ModuleSpecifierResolutionResult;
         resolvedAny: () => boolean;
         skippedAny: () => boolean;
@@ -190,15 +190,20 @@ namespace ts.Completions {
         preferences: UserPreferences,
         isForImportStatementCompletion: boolean,
         isValidTypeOnlyUseSite: boolean,
-        cb: (context: ModuleSpecifierResolutioContext) => TReturn,
+        cb: (context: ModuleSpecifierResolutionContext) => TReturn,
     ): TReturn {
         const start = timestamp();
+        const moduleResolution = getEmitModuleResolutionKind(program.getCompilerOptions());
         // Under `--moduleResolution nodenext`, we have to resolve module specifiers up front, because
         // package.json exports can mean we *can't* resolve a module specifier (that doesn't include a
         // relative path into node_modules), and we want to filter those completions out entirely.
+        // Under `--moduleResolution minimal`, we want to reject relative module specifiers into
+        // node_modules, so need to exhaust any other possibilities for how those can be referenced.
         // Import statement completions always need specifier resolution because the module specifier is
         // part of their `insertText`, not the `codeActions` creating edits away from the cursor.
-        const needsFullResolution = isForImportStatementCompletion || moduleResolutionRespectsExports(getEmitModuleResolutionKind(program.getCompilerOptions()));
+        const needsFullResolution = isForImportStatementCompletion
+            || moduleResolutionRespectsExports(moduleResolution)
+            || moduleResolution === ModuleResolutionKind.Minimal;
         let skippedAny = false;
         let ambientCount = 0;
         let resolvedCount = 0;
diff --git a/tests/baselines/reference/autoImportsMinimal1.baseline.md b/tests/baselines/reference/autoImportsMinimal1.baseline.md
new file mode 100644
index 0000000000000..cd47cab8187c3
--- /dev/null
+++ b/tests/baselines/reference/autoImportsMinimal1.baseline.md
@@ -0,0 +1,15 @@
+```ts
+// @Filename: /main.ts
+/*|*/
+```
+
+## From completions
+
+- `fromLocal` from `"./local.js"`
+
+```ts
+import { fromLocal } from "./local.js";
+
+fromLocal
+```
+
diff --git a/tests/baselines/reference/autoImportsMinimal2.baseline.md b/tests/baselines/reference/autoImportsMinimal2.baseline.md
new file mode 100644
index 0000000000000..56cf2c70c336a
--- /dev/null
+++ b/tests/baselines/reference/autoImportsMinimal2.baseline.md
@@ -0,0 +1,15 @@
+```ts
+// @Filename: /main.ts
+/*|*/
+```
+
+## From completions
+
+- `fromLocal` from `"./local.ts"`
+
+```ts
+import { fromLocal } from "./local.ts";
+
+fromLocal
+```
+

From 6242ee31a7cf36ae2ff29024d0145352220a6c45 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Mon, 26 Sep 2022 11:40:13 -0700
Subject: [PATCH 11/14] Test a non-portable declaration emit issue

---
 ...mal_nodeModules_declarationEmit.errors.txt | 17 +++++++++++++++
 .../minimal_nodeModules_declarationEmit.js    | 20 ++++++++++++++++++
 ...inimal_nodeModules_declarationEmit.symbols | 21 +++++++++++++++++++
 .../minimal_nodeModules_declarationEmit.types | 21 +++++++++++++++++++
 .../minimal_nodeModules_declarationEmit.ts    | 14 +++++++++++++
 5 files changed, 93 insertions(+)
 create mode 100644 tests/baselines/reference/minimal_nodeModules_declarationEmit.errors.txt
 create mode 100644 tests/baselines/reference/minimal_nodeModules_declarationEmit.js
 create mode 100644 tests/baselines/reference/minimal_nodeModules_declarationEmit.symbols
 create mode 100644 tests/baselines/reference/minimal_nodeModules_declarationEmit.types
 create mode 100644 tests/cases/conformance/moduleResolution/minimal_nodeModules_declarationEmit.ts

diff --git a/tests/baselines/reference/minimal_nodeModules_declarationEmit.errors.txt b/tests/baselines/reference/minimal_nodeModules_declarationEmit.errors.txt
new file mode 100644
index 0000000000000..d0ce84ea82c5c
--- /dev/null
+++ b/tests/baselines/reference/minimal_nodeModules_declarationEmit.errors.txt
@@ -0,0 +1,17 @@
+/main.ts(1,14): error TS2742: The inferred type of 'boom' cannot be named without a reference to './node_modules/foo/module.js'. This is likely not portable. A type annotation is necessary.
+
+
+==== /node_modules/foo/module.d.ts (0 errors) ====
+    export declare class SomeExportedClass {
+      private foo: any;
+    }
+    
+    declare global {
+      function returnsPrivateClassOhNo(): SomeExportedClass;
+    }
+    
+==== /main.ts (1 errors) ====
+    export const boom = returnsPrivateClassOhNo();
+                 ~~~~
+!!! error TS2742: The inferred type of 'boom' cannot be named without a reference to './node_modules/foo/module.js'. This is likely not portable. A type annotation is necessary.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/minimal_nodeModules_declarationEmit.js b/tests/baselines/reference/minimal_nodeModules_declarationEmit.js
new file mode 100644
index 0000000000000..b31f1936f6f13
--- /dev/null
+++ b/tests/baselines/reference/minimal_nodeModules_declarationEmit.js
@@ -0,0 +1,20 @@
+//// [tests/cases/conformance/moduleResolution/minimal_nodeModules_declarationEmit.ts] ////
+
+//// [module.d.ts]
+export declare class SomeExportedClass {
+  private foo: any;
+}
+
+declare global {
+  function returnsPrivateClassOhNo(): SomeExportedClass;
+}
+
+//// [main.ts]
+export const boom = returnsPrivateClassOhNo();
+
+
+//// [main.js]
+"use strict";
+exports.__esModule = true;
+exports.boom = void 0;
+exports.boom = returnsPrivateClassOhNo();
diff --git a/tests/baselines/reference/minimal_nodeModules_declarationEmit.symbols b/tests/baselines/reference/minimal_nodeModules_declarationEmit.symbols
new file mode 100644
index 0000000000000..1930da5f26c77
--- /dev/null
+++ b/tests/baselines/reference/minimal_nodeModules_declarationEmit.symbols
@@ -0,0 +1,21 @@
+=== /node_modules/foo/module.d.ts ===
+export declare class SomeExportedClass {
+>SomeExportedClass : Symbol(SomeExportedClass, Decl(module.d.ts, 0, 0))
+
+  private foo: any;
+>foo : Symbol(SomeExportedClass.foo, Decl(module.d.ts, 0, 40))
+}
+
+declare global {
+>global : Symbol(global, Decl(module.d.ts, 2, 1))
+
+  function returnsPrivateClassOhNo(): SomeExportedClass;
+>returnsPrivateClassOhNo : Symbol(returnsPrivateClassOhNo, Decl(module.d.ts, 4, 16))
+>SomeExportedClass : Symbol(SomeExportedClass, Decl(module.d.ts, 0, 0))
+}
+
+=== /main.ts ===
+export const boom = returnsPrivateClassOhNo();
+>boom : Symbol(boom, Decl(main.ts, 0, 12))
+>returnsPrivateClassOhNo : Symbol(returnsPrivateClassOhNo, Decl(module.d.ts, 4, 16))
+
diff --git a/tests/baselines/reference/minimal_nodeModules_declarationEmit.types b/tests/baselines/reference/minimal_nodeModules_declarationEmit.types
new file mode 100644
index 0000000000000..ab1b8fd4423c6
--- /dev/null
+++ b/tests/baselines/reference/minimal_nodeModules_declarationEmit.types
@@ -0,0 +1,21 @@
+=== /node_modules/foo/module.d.ts ===
+export declare class SomeExportedClass {
+>SomeExportedClass : SomeExportedClass
+
+  private foo: any;
+>foo : any
+}
+
+declare global {
+>global : typeof global
+
+  function returnsPrivateClassOhNo(): SomeExportedClass;
+>returnsPrivateClassOhNo : () => SomeExportedClass
+}
+
+=== /main.ts ===
+export const boom = returnsPrivateClassOhNo();
+>boom : import("/node_modules/foo/module").SomeExportedClass
+>returnsPrivateClassOhNo() : import("/node_modules/foo/module").SomeExportedClass
+>returnsPrivateClassOhNo : () => import("/node_modules/foo/module").SomeExportedClass
+
diff --git a/tests/cases/conformance/moduleResolution/minimal_nodeModules_declarationEmit.ts b/tests/cases/conformance/moduleResolution/minimal_nodeModules_declarationEmit.ts
new file mode 100644
index 0000000000000..b621aeab6431f
--- /dev/null
+++ b/tests/cases/conformance/moduleResolution/minimal_nodeModules_declarationEmit.ts
@@ -0,0 +1,14 @@
+// @moduleResolution: minimal
+// @declaration: true
+
+// @Filename: /node_modules/foo/module.d.ts
+export declare class SomeExportedClass {
+  private foo: any;
+}
+
+declare global {
+  function returnsPrivateClassOhNo(): SomeExportedClass;
+}
+
+// @Filename: /main.ts
+export const boom = returnsPrivateClassOhNo();

From 6cc0e18dca2006e4751f8d1d680fdb42723915aa Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Mon, 26 Sep 2022 11:44:03 -0700
Subject: [PATCH 12/14] Test auto-importing TSX file

---
 tests/baselines/reference/autoImportsMinimal1.baseline.md | 7 +++++++
 tests/baselines/reference/autoImportsMinimal2.baseline.md | 7 +++++++
 tests/cases/fourslash/autoImportsMinimal1.ts              | 3 +++
 tests/cases/fourslash/autoImportsMinimal2.ts              | 3 +++
 4 files changed, 20 insertions(+)

diff --git a/tests/baselines/reference/autoImportsMinimal1.baseline.md b/tests/baselines/reference/autoImportsMinimal1.baseline.md
index cd47cab8187c3..c0a6fb0eeaaaa 100644
--- a/tests/baselines/reference/autoImportsMinimal1.baseline.md
+++ b/tests/baselines/reference/autoImportsMinimal1.baseline.md
@@ -5,8 +5,15 @@
 
 ## From completions
 
+- `Component` from `"./Component.js"`
 - `fromLocal` from `"./local.js"`
 
+```ts
+import { Component } from "./Component.js";
+
+Component
+```
+
 ```ts
 import { fromLocal } from "./local.js";
 
diff --git a/tests/baselines/reference/autoImportsMinimal2.baseline.md b/tests/baselines/reference/autoImportsMinimal2.baseline.md
index 56cf2c70c336a..35b129182eab9 100644
--- a/tests/baselines/reference/autoImportsMinimal2.baseline.md
+++ b/tests/baselines/reference/autoImportsMinimal2.baseline.md
@@ -5,8 +5,15 @@
 
 ## From completions
 
+- `Component` from `"./Component.tsx"`
 - `fromLocal` from `"./local.ts"`
 
+```ts
+import { Component } from "./Component.tsx";
+
+Component
+```
+
 ```ts
 import { fromLocal } from "./local.ts";
 
diff --git a/tests/cases/fourslash/autoImportsMinimal1.ts b/tests/cases/fourslash/autoImportsMinimal1.ts
index 175f731e3abf8..1796a03b00f28 100644
--- a/tests/cases/fourslash/autoImportsMinimal1.ts
+++ b/tests/cases/fourslash/autoImportsMinimal1.ts
@@ -11,6 +11,9 @@
 // @Filename: /local.ts
 //// export const fromLocal: number;
 
+// @Filename: /Component.tsx
+//// export function Component() { return null; }
+
 // @Filename: /main.ts
 //// /**/
 
diff --git a/tests/cases/fourslash/autoImportsMinimal2.ts b/tests/cases/fourslash/autoImportsMinimal2.ts
index 3ab44e1c00da4..c98a84aa859be 100644
--- a/tests/cases/fourslash/autoImportsMinimal2.ts
+++ b/tests/cases/fourslash/autoImportsMinimal2.ts
@@ -13,6 +13,9 @@
 // @Filename: /local.ts
 //// export const fromLocal: number;
 
+// @Filename: /Component.tsx
+//// export function Component() { return null; }
+
 // @Filename: /main.ts
 //// /**/
 

From 240533a2361babab5e1fe5e38c4ac35fde77c5c8 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Mon, 26 Sep 2022 12:59:25 -0700
Subject: [PATCH 13/14] Update path completions

---
 src/services/stringCompletions.ts             | 85 ++++++++++---------
 .../fourslash/pathCompletionsMinimal1.ts      | 31 +++++++
 .../fourslash/pathCompletionsMinimal2.ts      | 33 +++++++
 3 files changed, 109 insertions(+), 40 deletions(-)
 create mode 100644 tests/cases/fourslash/pathCompletionsMinimal1.ts
 create mode 100644 tests/cases/fourslash/pathCompletionsMinimal2.ts

diff --git a/src/services/stringCompletions.ts b/src/services/stringCompletions.ts
index 922e50654bbe1..df0aeb202b2ae 100644
--- a/src/services/stringCompletions.ts
+++ b/src/services/stringCompletions.ts
@@ -377,8 +377,16 @@ namespace ts.Completions.StringCompletions {
             : getCompletionEntriesForNonRelativeModules(literalValue, scriptDirectory, mode, compilerOptions, host, getIncludeExtensionOption(), typeChecker);
 
         function getIncludeExtensionOption() {
+            const moduleResolution = getEmitModuleResolutionKind(compilerOptions);
+            if (moduleResolution === ModuleResolutionKind.Minimal) {
+                return shouldAllowImportingTsExtension(compilerOptions)
+                    ? IncludeExtensionsOption.Include
+                    : IncludeExtensionsOption.ModuleSpecifierCompletion;
+            }
             const mode = isStringLiteralLike(node) ? getModeForUsageLocation(sourceFile, node) : undefined;
-            return preferences.importModuleSpecifierEnding === "js" || mode === ModuleKind.ESNext ? IncludeExtensionsOption.ModuleSpecifierCompletion : IncludeExtensionsOption.Exclude;
+            return preferences.importModuleSpecifierEnding === "js" || mode === ModuleKind.ESNext
+                ? IncludeExtensionsOption.ModuleSpecifierCompletion
+                : IncludeExtensionsOption.Exclude;
         }
     }
 
@@ -396,24 +404,14 @@ namespace ts.Completions.StringCompletions {
                 compilerOptions.rootDirs, literalValue, scriptDirectory, extensionOptions, compilerOptions, host, scriptPath);
         }
         else {
-            return arrayFrom(getCompletionEntriesForDirectoryFragment(literalValue, scriptDirectory, extensionOptions, host, scriptPath).values());
+            return arrayFrom(getCompletionEntriesForDirectoryFragment(literalValue, scriptDirectory, extensionOptions, host, /*moduleSpecifierIsRelative*/ false, scriptPath).values());
         }
     }
 
-    function isEmitResolutionKindUsingNodeModules(compilerOptions: CompilerOptions): boolean {
-        return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeJs ||
-            getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 ||
-            getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext;
-    }
-
-    function isEmitModuleResolutionRespectingExportMaps(compilerOptions: CompilerOptions) {
-        return getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.Node16 ||
-        getEmitModuleResolutionKind(compilerOptions) === ModuleResolutionKind.NodeNext;
-    }
-
     function getSupportedExtensionsForModuleResolution(compilerOptions: CompilerOptions): readonly Extension[][] {
         const extensions = getSupportedExtensions(compilerOptions);
-        return isEmitResolutionKindUsingNodeModules(compilerOptions) ?
+        const moduleResolution = getEmitModuleResolutionKind(compilerOptions);
+        return moduleResolutionUsesNodeModules(moduleResolution) ?
             getSupportedExtensionsWithJsonIfResolveJsonModule(compilerOptions, extensions) :
             extensions;
     }
@@ -441,7 +439,7 @@ namespace ts.Completions.StringCompletions {
         const basePath = compilerOptions.project || host.getCurrentDirectory();
         const ignoreCase = !(host.useCaseSensitiveFileNames && host.useCaseSensitiveFileNames());
         const baseDirectories = getBaseDirectoriesFromRootDirs(rootDirs, basePath, scriptDirectory, ignoreCase);
-        return flatMap(baseDirectories, baseDirectory => arrayFrom(getCompletionEntriesForDirectoryFragment(fragment, baseDirectory, extensionOptions, host, exclude).values()));
+        return flatMap(baseDirectories, baseDirectory => arrayFrom(getCompletionEntriesForDirectoryFragment(fragment, baseDirectory, extensionOptions, host, /*moduleSpecifierIsRelative*/ true, exclude).values()));
     }
 
     const enum IncludeExtensionsOption {
@@ -454,9 +452,10 @@ namespace ts.Completions.StringCompletions {
      */
     function getCompletionEntriesForDirectoryFragment(
         fragment: string,
-        scriptPath: string,
+        scriptDirectory: string,
         extensionOptions: ExtensionOptions,
         host: LanguageServiceHost,
+        moduleSpecifierIsRelative: boolean,
         exclude?: string,
         result = createNameAndKindSet()
     ): NameAndKindSet {
@@ -480,23 +479,25 @@ namespace ts.Completions.StringCompletions {
 
         fragment = ensureTrailingDirectorySeparator(fragment);
 
-        const absolutePath = resolvePath(scriptPath, fragment);
+        const absolutePath = resolvePath(scriptDirectory, fragment);
         const baseDirectory = hasTrailingDirectorySeparator(absolutePath) ? absolutePath : getDirectoryPath(absolutePath);
 
-        // check for a version redirect
-        const packageJsonPath = findPackageJson(baseDirectory, host);
-        if (packageJsonPath) {
-            const packageJson = readJson(packageJsonPath, host as { readFile: (filename: string) => string | undefined });
-            const typesVersions = (packageJson as any).typesVersions;
-            if (typeof typesVersions === "object") {
-                const versionPaths = getPackageJsonTypesVersionsPaths(typesVersions)?.paths;
-                if (versionPaths) {
-                    const packageDirectory = getDirectoryPath(packageJsonPath);
-                    const pathInPackage = absolutePath.slice(ensureTrailingDirectorySeparator(packageDirectory).length);
-                    if (addCompletionEntriesFromPaths(result, pathInPackage, packageDirectory, extensionOptions, host, versionPaths)) {
-                        // A true result means one of the `versionPaths` was matched, which will block relative resolution
-                        // to files and folders from here. All reachable paths given the pattern match are already added.
-                        return result;
+        if (!moduleSpecifierIsRelative) {
+            // check for a version redirect
+            const packageJsonPath = findPackageJson(baseDirectory, host);
+            if (packageJsonPath) {
+                const packageJson = readJson(packageJsonPath, host as { readFile: (filename: string) => string | undefined });
+                const typesVersions = (packageJson as any).typesVersions;
+                if (typeof typesVersions === "object") {
+                    const versionPaths = getPackageJsonTypesVersionsPaths(typesVersions)?.paths;
+                    if (versionPaths) {
+                        const packageDirectory = getDirectoryPath(packageJsonPath);
+                        const pathInPackage = absolutePath.slice(ensureTrailingDirectorySeparator(packageDirectory).length);
+                        if (addCompletionEntriesFromPaths(result, pathInPackage, packageDirectory, extensionOptions, host, versionPaths)) {
+                            // A true result means one of the `versionPaths` was matched, which will block relative resolution
+                            // to files and folders from here. All reachable paths given the pattern match are already added.
+                            return result;
+                        }
                     }
                 }
             }
@@ -511,7 +512,7 @@ namespace ts.Completions.StringCompletions {
         if (files) {
             for (let filePath of files) {
                 filePath = normalizePath(filePath);
-                if (exclude && comparePaths(filePath, exclude, scriptPath, ignoreCase) === Comparison.EqualTo) {
+                if (exclude && comparePaths(filePath, exclude, scriptDirectory, ignoreCase) === Comparison.EqualTo) {
                     continue;
                 }
 
@@ -524,9 +525,10 @@ namespace ts.Completions.StringCompletions {
         const directories = tryGetDirectories(host, baseDirectory);
 
         if (directories) {
+            const moduleResolution = getEmitModuleResolutionKind(host.getCompilationSettings());
             for (const directory of directories) {
                 const directoryName = getBaseFileName(normalizePath(directory));
-                if (directoryName !== "@types") {
+                if (directoryName !== "@types" && !(directoryName === "node_modules" && moduleResolution === ModuleResolutionKind.Minimal)) {
                     result.add(directoryResult(directoryName));
                 }
             }
@@ -638,11 +640,12 @@ namespace ts.Completions.StringCompletions {
         const { baseUrl, paths } = compilerOptions;
 
         const result = createNameAndKindSet();
+        const moduleResolution = getEmitModuleResolutionKind(compilerOptions);
         const extensionOptions = getExtensionOptions(compilerOptions, includeExtensionsOption);
         if (baseUrl) {
             const projectDir = compilerOptions.project || host.getCurrentDirectory();
             const absolute = normalizePath(combinePaths(projectDir, baseUrl));
-            getCompletionEntriesForDirectoryFragment(fragment, absolute, extensionOptions, host, /*exclude*/ undefined, result);
+            getCompletionEntriesForDirectoryFragment(fragment, absolute, extensionOptions, host, /*moduleSpecifierIsRelative*/ false, /*exclude*/ undefined, result);
             if (paths) {
                 addCompletionEntriesFromPaths(result, fragment, absolute, extensionOptions, host, paths);
             }
@@ -653,9 +656,11 @@ namespace ts.Completions.StringCompletions {
             result.add(nameAndKind(ambientName, ScriptElementKind.externalModuleName, /*extension*/ undefined));
         }
 
-        getCompletionEntriesFromTypings(host, compilerOptions, scriptPath, fragmentDirectory, extensionOptions, result);
+        if (moduleResolution !== ModuleResolutionKind.Minimal) {
+            getCompletionEntriesFromTypings(host, compilerOptions, scriptPath, fragmentDirectory, extensionOptions, result);
+        }
 
-        if (isEmitResolutionKindUsingNodeModules(compilerOptions)) {
+        if (moduleResolutionUsesNodeModules(moduleResolution)) {
             // If looking for a global package name, don't just include everything in `node_modules` because that includes dependencies' own dependencies.
             // (But do if we didn't find anything, e.g. 'package.json' missing.)
             let foundGlobal = false;
@@ -672,10 +677,10 @@ namespace ts.Completions.StringCompletions {
                 let ancestorLookup: (directory: string) => void | undefined = ancestor => {
                     const nodeModules = combinePaths(ancestor, "node_modules");
                     if (tryDirectoryExists(host, nodeModules)) {
-                        getCompletionEntriesForDirectoryFragment(fragment, nodeModules, extensionOptions, host, /*exclude*/ undefined, result);
+                        getCompletionEntriesForDirectoryFragment(fragment, nodeModules, extensionOptions, host, /*moduleSpecifierIsRelative*/ false, /*exclude*/ undefined, result);
                     }
                 };
-                if (fragmentDirectory && isEmitModuleResolutionRespectingExportMaps(compilerOptions)) {
+                if (fragmentDirectory && moduleResolutionRespectsExports(moduleResolution)) {
                     const nodeModulesDirectoryLookup = ancestorLookup;
                     ancestorLookup = ancestor => {
                         const components = getPathComponents(fragment);
@@ -876,7 +881,7 @@ namespace ts.Completions.StringCompletions {
 
         const [, prefix, kind, toComplete] = match;
         const scriptPath = getDirectoryPath(sourceFile.path);
-        const names = kind === "path" ? getCompletionEntriesForDirectoryFragment(toComplete, scriptPath, getExtensionOptions(compilerOptions, IncludeExtensionsOption.Include), host, sourceFile.path)
+        const names = kind === "path" ? getCompletionEntriesForDirectoryFragment(toComplete, scriptPath, getExtensionOptions(compilerOptions, IncludeExtensionsOption.Include), host, /*moduleSpecifierIsRelative*/ true, sourceFile.path)
             : kind === "types" ? getCompletionEntriesFromTypings(host, compilerOptions, scriptPath, getFragmentDirectory(toComplete), getExtensionOptions(compilerOptions))
             : Debug.fail();
         return addReplacementSpans(toComplete, range.pos + prefix.length, arrayFrom(names.values()));
@@ -917,7 +922,7 @@ namespace ts.Completions.StringCompletions {
                     const baseDirectory = combinePaths(directory, typeDirectoryName);
                     const remainingFragment = tryRemoveDirectoryPrefix(fragmentDirectory, packageName, hostGetCanonicalFileName(host));
                     if (remainingFragment !== undefined) {
-                        getCompletionEntriesForDirectoryFragment(remainingFragment, baseDirectory, extensionOptions, host, /*exclude*/ undefined, result);
+                        getCompletionEntriesForDirectoryFragment(remainingFragment, baseDirectory, extensionOptions, host, /*moduleSpecifierIsRelative*/ false, /*exclude*/ undefined, result);
                     }
                 }
             }
diff --git a/tests/cases/fourslash/pathCompletionsMinimal1.ts b/tests/cases/fourslash/pathCompletionsMinimal1.ts
new file mode 100644
index 0000000000000..a3843b535f648
--- /dev/null
+++ b/tests/cases/fourslash/pathCompletionsMinimal1.ts
@@ -0,0 +1,31 @@
+/// <reference path="fourslash.ts" />
+
+// @moduleResolution: minimal
+
+// @Filename: /project/node_modules/@types/foo/index.d.ts
+//// export const fromAtTypesFoo: number;
+
+// @Filename: /project/node_modules/bar/index.d.ts
+//// export const fromBar: number;
+
+// @Filename: /project/local.ts
+//// export const fromLocal: number;
+
+// @Filename: /project/Component.tsx
+//// export function Component() { return null; }
+
+// @Filename: /project/main.ts
+//// import {} from "/**/";
+
+verify.completions({
+  isNewIdentifierLocation: true,
+  marker: "",
+  exact: []
+});
+
+edit.insert("./");
+
+verify.completions({
+  isNewIdentifierLocation: true,
+  exact: ["Component.js", "local.js"],
+});
diff --git a/tests/cases/fourslash/pathCompletionsMinimal2.ts b/tests/cases/fourslash/pathCompletionsMinimal2.ts
new file mode 100644
index 0000000000000..e9a27356b02b3
--- /dev/null
+++ b/tests/cases/fourslash/pathCompletionsMinimal2.ts
@@ -0,0 +1,33 @@
+/// <reference path="fourslash.ts" />
+
+// @moduleResolution: minimal
+// @allowImportingTsExtensions: true
+// @noEmit: true
+
+// @Filename: /project/node_modules/@types/foo/index.d.ts
+//// export const fromAtTypesFoo: number;
+
+// @Filename: /project/node_modules/bar/index.d.ts
+//// export const fromBar: number;
+
+// @Filename: /project/local.ts
+//// export const fromLocal: number;
+
+// @Filename: /project/Component.tsx
+//// export function Component() { return null; }
+
+// @Filename: /project/main.ts
+//// import {} from "/**/";
+
+verify.completions({
+  isNewIdentifierLocation: true,
+  marker: "",
+  exact: []
+});
+
+edit.insert("./");
+
+verify.completions({
+  isNewIdentifierLocation: true,
+  exact: ["Component.tsx", "local.ts"],
+});

From 619843e0d0bbc116fffe364fe8264dcc3668308b Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Tue, 27 Sep 2022 10:20:31 -0700
Subject: [PATCH 14/14] Fix lint due to merge

---
 src/compiler/checker.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index e27ddd533a58e..8842735df2942 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -3637,7 +3637,7 @@ namespace ts {
                 else if (resolvedModule.resolvedUsingTsExtension && isDeclarationFileName(moduleReference)) {
                     const importOrExport =
                         findAncestor(location, isImportDeclaration)?.importClause ||
-                        findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration)) as ImportEqualsDeclaration | ExportDeclaration | undefined;
+                        findAncestor(location, or(isImportEqualsDeclaration, isExportDeclaration));
                     if (importOrExport && !importOrExport.isTypeOnly || findAncestor(location, isImportCall)) {
                         error(
                             errorNode,

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