microsoft · ahejlsberg · Jul 21, 2020 · Jul 20, 2020 · Jul 20, 2020 · Jul 20, 2020
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -166,6 +166,7 @@ namespace ts {
         ImmediateBaseConstraint,
         EnumTagType,
         ResolvedTypeArguments,
+        ResolvedBaseTypes,
     }
 
     const enum CheckMode {
@@ -7491,6 +7492,8 @@ namespace ts {
                     return !!(<Type>target).immediateBaseConstraint;
                 case TypeSystemPropertyName.ResolvedTypeArguments:
                     return !!(target as TypeReference).resolvedTypeArguments;
+                case TypeSystemPropertyName.ResolvedBaseTypes:
+                    return !!(target as InterfaceType).baseTypesResolved;
             }
             return Debug.assertNever(propertyName);
         }
@@ -8917,22 +8920,36 @@ namespace ts {
             return resolvedImplementsTypes;
         }
 
+        function reportCircularBaseType(node: Node, type: Type) {
+            error(node, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType));
+        }
+
         function getBaseTypes(type: InterfaceType): BaseType[] {
-            if (!type.resolvedBaseTypes) {
-                if (type.objectFlags & ObjectFlags.Tuple) {
-                    type.resolvedBaseTypes = [getTupleBaseType(<TupleType>type)];
-                }
-                else if (type.symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) {
-                    if (type.symbol.flags & SymbolFlags.Class) {
-                        resolveBaseTypesOfClass(type);
+            if (!type.baseTypesResolved) {
+                if (pushTypeResolution(type, TypeSystemPropertyName.ResolvedBaseTypes)) {
+                    if (type.objectFlags & ObjectFlags.Tuple) {
+                        type.resolvedBaseTypes = [getTupleBaseType(<TupleType>type)];
                     }
-                    if (type.symbol.flags & SymbolFlags.Interface) {
-                        resolveBaseTypesOfInterface(type);
+                    else if (type.symbol.flags & (SymbolFlags.Class | SymbolFlags.Interface)) {
+                        if (type.symbol.flags & SymbolFlags.Class) {
+                            resolveBaseTypesOfClass(type);
+                        }
+                        if (type.symbol.flags & SymbolFlags.Interface) {
+                            resolveBaseTypesOfInterface(type);
+                        }
+                    }
+                    else {
+                        Debug.fail("type must be class or interface");
+                    }
+                    if (!popTypeResolution()) {
+                        for (const declaration of type.symbol.declarations) {
+                            if (declaration.kind === SyntaxKind.ClassDeclaration || declaration.kind === SyntaxKind.InterfaceDeclaration) {
+                                reportCircularBaseType(declaration, type);
+                            }
+                        }
                     }
                 }
-                else {
-                    Debug.fail("type must be class or interface");
-                }
+                type.baseTypesResolved = true;
             }
             return type.resolvedBaseTypes;
         }
@@ -9041,7 +9058,7 @@ namespace ts {
                                     }
                                 }
                                 else {
-                                    error(declaration, Diagnostics.Type_0_recursively_references_itself_as_a_base_type, typeToString(type, /*enclosingDeclaration*/ undefined, TypeFormatFlags.WriteArrayAsGenericType));
+                                    reportCircularBaseType(declaration, type);
                                 }
                             }
                             else {

diff --git a/src/compiler/types.ts b/src/compiler/types.ts
@@ -5050,6 +5050,8 @@ namespace ts {
         resolvedBaseConstructorType?: Type;               // Resolved base constructor type of class
         /* @internal */
         resolvedBaseTypes: BaseType[];                    // Resolved base types
+        /* @internal */
+        baseTypesResolved?: boolean;
     }
 
     // Object type or intersection of object types

diff --git a/tests/baselines/reference/circularBaseTypes.errors.txt b/tests/baselines/reference/circularBaseTypes.errors.txt
@@ -0,0 +1,19 @@
+tests/cases/compiler/circularBaseTypes.ts(4,11): error TS2310: Type 'M2' recursively references itself as a base type.
+tests/cases/compiler/circularBaseTypes.ts(5,6): error TS2456: Type alias 'M3' circularly references itself.
+
+
+==== tests/cases/compiler/circularBaseTypes.ts (2 errors) ====
+    // Repro from #38098
+
+    type M<T> = { value: T };
+    interface M2 extends M<M3> {};  // Error
+              ~~
+!!! error TS2310: Type 'M2' recursively references itself as a base type.
+    type M3 = M2[keyof M2];  // Error
+         ~~
+!!! error TS2456: Type alias 'M3' circularly references itself.
+
+    function f(m: M3) {
+      return m.value;
+    }
+
diff --git a/tests/baselines/reference/circularBaseTypes.js b/tests/baselines/reference/circularBaseTypes.js
@@ -0,0 +1,29 @@
+//// [circularBaseTypes.ts]
+// Repro from #38098
+
+type M<T> = { value: T };
+interface M2 extends M<M3> {};  // Error
+type M3 = M2[keyof M2];  // Error
+
+function f(m: M3) {
+  return m.value;
+}
+
+
+//// [circularBaseTypes.js]
+"use strict";
+// Repro from #38098
+; // Error
+function f(m) {
+    return m.value;
+}
+
+
+//// [circularBaseTypes.d.ts]
+declare type M<T> = {
+    value: T;
+};
+interface M2 extends M<M3> {
+}
+declare type M3 = M2[keyof M2];
+declare function f(m: M3): any;
diff --git a/tests/baselines/reference/circularBaseTypes.symbols b/tests/baselines/reference/circularBaseTypes.symbols
@@ -0,0 +1,28 @@
+=== tests/cases/compiler/circularBaseTypes.ts ===
+// Repro from #38098
+
+type M<T> = { value: T };
+>M : Symbol(M, Decl(circularBaseTypes.ts, 0, 0))
+>T : Symbol(T, Decl(circularBaseTypes.ts, 2, 7))
+>value : Symbol(value, Decl(circularBaseTypes.ts, 2, 13))
+>T : Symbol(T, Decl(circularBaseTypes.ts, 2, 7))
+
+interface M2 extends M<M3> {};  // Error
+>M2 : Symbol(M2, Decl(circularBaseTypes.ts, 2, 25))
+>M : Symbol(M, Decl(circularBaseTypes.ts, 0, 0))
+>M3 : Symbol(M3, Decl(circularBaseTypes.ts, 3, 30))
+
+type M3 = M2[keyof M2];  // Error
+>M3 : Symbol(M3, Decl(circularBaseTypes.ts, 3, 30))
+>M2 : Symbol(M2, Decl(circularBaseTypes.ts, 2, 25))
+>M2 : Symbol(M2, Decl(circularBaseTypes.ts, 2, 25))
+
+function f(m: M3) {
+>f : Symbol(f, Decl(circularBaseTypes.ts, 4, 23))
+>m : Symbol(m, Decl(circularBaseTypes.ts, 6, 11))
+>M3 : Symbol(M3, Decl(circularBaseTypes.ts, 3, 30))
+
+  return m.value;
+>m : Symbol(m, Decl(circularBaseTypes.ts, 6, 11))
+}
+
diff --git a/tests/baselines/reference/circularBaseTypes.types b/tests/baselines/reference/circularBaseTypes.types
@@ -0,0 +1,21 @@
+=== tests/cases/compiler/circularBaseTypes.ts ===
+// Repro from #38098
+
+type M<T> = { value: T };
+>M : M<T>
+>value : T
+
+interface M2 extends M<M3> {};  // Error
+type M3 = M2[keyof M2];  // Error
+>M3 : any
+
+function f(m: M3) {
+>f : (m: any) => any
+>m : any
+
+  return m.value;
+>m.value : any
+>m : any
+>value : any
+}
+
diff --git a/tests/baselines/reference/circularConstraintYieldsAppropriateError.errors.txt b/tests/baselines/reference/circularConstraintYieldsAppropriateError.errors.txt
@@ -0,0 +1,23 @@
+tests/cases/compiler/circularConstraintYieldsAppropriateError.ts(10,7): error TS2310: Type 'Foo' recursively references itself as a base type.
+
+
+==== tests/cases/compiler/circularConstraintYieldsAppropriateError.ts (1 errors) ====
+    // https://github.com/Microsoft/TypeScript/issues/16861
+    class BaseType<T> {
+        bar: T
+    }
+
+    class NextType<C extends { someProp: any }, T = C['someProp']> extends BaseType<T> {
+        baz: string;
+    }
+
+    class Foo extends NextType<Foo> {
+          ~~~
+!!! error TS2310: Type 'Foo' recursively references itself as a base type.
+        someProp: {
+            test: true
+        }
+    }
+
+    const foo = new Foo();
+    foo.bar.test
diff --git a/tests/baselines/reference/interfaceDeclaration1.errors.txt b/tests/baselines/reference/interfaceDeclaration1.errors.txt
@@ -7,11 +7,12 @@ tests/cases/compiler/interfaceDeclaration1.ts(22,11): error TS2310: Type 'I5' re
 tests/cases/compiler/interfaceDeclaration1.ts(35,7): error TS2420: Class 'C1' incorrectly implements interface 'I3'.
   Property 'prototype' is missing in type 'C1' but required in type 'I3'.
 tests/cases/compiler/interfaceDeclaration1.ts(41,11): error TS2310: Type 'i8' recursively references itself as a base type.
+tests/cases/compiler/interfaceDeclaration1.ts(42,11): error TS2310: Type 'i9' recursively references itself as a base type.
 tests/cases/compiler/interfaceDeclaration1.ts(52,11): error TS2320: Interface 'i12' cannot simultaneously extend types 'i10' and 'i11'.
   Named property 'foo' of types 'i10' and 'i11' are not identical.
 
 
-==== tests/cases/compiler/interfaceDeclaration1.ts (9 errors) ====
+==== tests/cases/compiler/interfaceDeclaration1.ts (10 errors) ====
     interface I1 {
         item:number;
         ~~~~
@@ -73,6 +74,8 @@ tests/cases/compiler/interfaceDeclaration1.ts(52,11): error TS2320: Interface 'i
               ~~
 !!! error TS2310: Type 'i8' recursively references itself as a base type.
     interface i9 extends i8 { }
+              ~~
+!!! error TS2310: Type 'i9' recursively references itself as a base type.
 
     interface i10 {
     	foo():number;

diff --git a/tests/baselines/reference/interfaceThatIndirectlyInheritsFromItself.errors.txt b/tests/baselines/reference/interfaceThatIndirectlyInheritsFromItself.errors.txt
@@ -1,19 +1,27 @@
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectlyInheritsFromItself.ts(1,11): error TS2310: Type 'Base' recursively references itself as a base type.
+tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectlyInheritsFromItself.ts(5,11): error TS2310: Type 'Derived' recursively references itself as a base type.
+tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectlyInheritsFromItself.ts(9,11): error TS2310: Type 'Derived2' recursively references itself as a base type.
 tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectlyInheritsFromItself.ts(14,15): error TS2310: Type 'Base<T>' recursively references itself as a base type.
+tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectlyInheritsFromItself.ts(18,15): error TS2310: Type 'Derived<T>' recursively references itself as a base type.
+tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectlyInheritsFromItself.ts(22,15): error TS2310: Type 'Derived2<T>' recursively references itself as a base type.
 
 
-==== tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectlyInheritsFromItself.ts (2 errors) ====
+==== tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectlyInheritsFromItself.ts (6 errors) ====
     interface Base extends Derived2 { // error
               ~~~~
 !!! error TS2310: Type 'Base' recursively references itself as a base type.
         x: string;
     }
 
     interface Derived extends Base {
+              ~~~~~~~
+!!! error TS2310: Type 'Derived' recursively references itself as a base type.
         y: string;
     }
 
     interface Derived2 extends Derived {
+              ~~~~~~~~
+!!! error TS2310: Type 'Derived2' recursively references itself as a base type.
         z: string;
     }
 
@@ -25,10 +33,14 @@ tests/cases/conformance/interfaces/interfaceDeclarations/interfaceThatIndirectly
         }
 
         interface Derived<T> extends Base<T> {
+                  ~~~~~~~
+!!! error TS2310: Type 'Derived<T>' recursively references itself as a base type.
             y: string;
         }
 
         interface Derived2<T> extends Derived<T> {
+                  ~~~~~~~~
+!!! error TS2310: Type 'Derived2<T>' recursively references itself as a base type.
             z: string;
         }
     }
diff --git a/tests/baselines/reference/recursiveBaseCheck5.errors.txt b/tests/baselines/reference/recursiveBaseCheck5.errors.txt
@@ -1,12 +1,15 @@
 tests/cases/compiler/recursiveBaseCheck5.ts(1,11): error TS2310: Type 'I1<T>' recursively references itself as a base type.
+tests/cases/compiler/recursiveBaseCheck5.ts(2,11): error TS2310: Type 'I2<T>' recursively references itself as a base type.
 tests/cases/compiler/recursiveBaseCheck5.ts(4,9): error TS2339: Property 'blah' does not exist on type 'X<unknown, unknown>'.
 
 
-==== tests/cases/compiler/recursiveBaseCheck5.ts (2 errors) ====
+==== tests/cases/compiler/recursiveBaseCheck5.ts (3 errors) ====
     interface I1<T> extends I2<string> { }
               ~~
 !!! error TS2310: Type 'I1<T>' recursively references itself as a base type.
     interface I2<T> extends I1<T> { }
+              ~~
+!!! error TS2310: Type 'I2<T>' recursively references itself as a base type.
     class X<T, U> implements I2<T> { }
     (new X).blah;
             ~~~~

diff --git a/tests/baselines/reference/recursiveInheritance.errors.txt b/tests/baselines/reference/recursiveInheritance.errors.txt
@@ -1,8 +1,9 @@
 tests/cases/compiler/recursiveInheritance.ts(1,11): error TS2310: Type 'I5' recursively references itself as a base type.
 tests/cases/compiler/recursiveInheritance.ts(5,11): error TS2310: Type 'i8' recursively references itself as a base type.
+tests/cases/compiler/recursiveInheritance.ts(6,11): error TS2310: Type 'i9' recursively references itself as a base type.
 
 
-==== tests/cases/compiler/recursiveInheritance.ts (2 errors) ====
+==== tests/cases/compiler/recursiveInheritance.ts (3 errors) ====
     interface I5 extends I5 { // error
               ~~
 !!! error TS2310: Type 'I5' recursively references itself as a base type.
@@ -13,4 +14,6 @@ tests/cases/compiler/recursiveInheritance.ts(5,11): error TS2310: Type 'i8' recu
               ~~
 !!! error TS2310: Type 'i8' recursively references itself as a base type.
     interface i9 extends i8 { } // error
+              ~~
+!!! error TS2310: Type 'i9' recursively references itself as a base type.
 
diff --git a/tests/cases/compiler/circularBaseTypes.ts b/tests/cases/compiler/circularBaseTypes.ts
@@ -0,0 +1,12 @@
+// @strict: true
+// @declaration: true
+
+// Repro from #38098
+
+type M<T> = { value: T };
+interface M2 extends M<M3> {};  // Error
+type M3 = M2[keyof M2];  // Error
+
+function f(m: M3) {
+  return m.value;
+}