From 307b09b58b4ebe54fe12d1274f077121bd6e8f96 Mon Sep 17 00:00:00 2001
From: Hans Brende <hans@imuto.ai>
Date: Fri, 9 May 2025 16:06:07 -0500
Subject: [PATCH] fix 61547

---
 src/compiler/checker.ts                       |  2 +-
 ...tOptionalPropertyTypesIdentical.errors.txt | 15 +++++++++++++++
 .../exactOptionalPropertyTypesIdentical.js    | 13 +++++++++++++
 ...xactOptionalPropertyTypesIdentical.symbols | 16 ++++++++++++++++
 .../exactOptionalPropertyTypesIdentical.types | 19 +++++++++++++++++++
 .../exactOptionalPropertyTypesIdentical.ts    |  5 +++++
 6 files changed, 69 insertions(+), 1 deletion(-)
 create mode 100644 tests/baselines/reference/exactOptionalPropertyTypesIdentical.errors.txt
 create mode 100644 tests/baselines/reference/exactOptionalPropertyTypesIdentical.js
 create mode 100644 tests/baselines/reference/exactOptionalPropertyTypesIdentical.symbols
 create mode 100644 tests/baselines/reference/exactOptionalPropertyTypesIdentical.types
 create mode 100644 tests/cases/compiler/exactOptionalPropertyTypesIdentical.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 073c0d46d7b4e..ee8b72d303487 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -25115,7 +25115,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         if (isReadonlySymbol(sourceProp) !== isReadonlySymbol(targetProp)) {
             return Ternary.False;
         }
-        return compareTypes(getTypeOfSymbol(sourceProp), getTypeOfSymbol(targetProp));
+        return compareTypes(getNonMissingTypeOfSymbol(sourceProp), getNonMissingTypeOfSymbol(targetProp));
     }
 
     function isMatchingSignature(source: Signature, target: Signature, partialMatch: boolean) {
diff --git a/tests/baselines/reference/exactOptionalPropertyTypesIdentical.errors.txt b/tests/baselines/reference/exactOptionalPropertyTypesIdentical.errors.txt
new file mode 100644
index 0000000000000..8ed639135a13f
--- /dev/null
+++ b/tests/baselines/reference/exactOptionalPropertyTypesIdentical.errors.txt
@@ -0,0 +1,15 @@
+exactOptionalPropertyTypesIdentical.ts(2,12): error TS2322: Type '<T>() => T extends { a?: string; } ? 0 : 1' is not assignable to type '<T>() => T extends { a?: string | undefined; } ? 0 : 1'.
+  Type 'T extends { a?: string; } ? 0 : 1' is not assignable to type 'T extends { a?: string | undefined; } ? 0 : 1'.
+    Type '0 | 1' is not assignable to type 'T extends { a?: string | undefined; } ? 0 : 1'.
+      Type '0' is not assignable to type 'T extends { a?: string | undefined; } ? 0 : 1'.
+
+
+==== exactOptionalPropertyTypesIdentical.ts (1 errors) ====
+    export let a: <T>() => T extends {a?: string} ? 0 : 1 = null!;
+    export let b: <T>() => T extends {a?: string | undefined} ? 0 : 1 = a;
+               ~
+!!! error TS2322: Type '<T>() => T extends { a?: string; } ? 0 : 1' is not assignable to type '<T>() => T extends { a?: string | undefined; } ? 0 : 1'.
+!!! error TS2322:   Type 'T extends { a?: string; } ? 0 : 1' is not assignable to type 'T extends { a?: string | undefined; } ? 0 : 1'.
+!!! error TS2322:     Type '0 | 1' is not assignable to type 'T extends { a?: string | undefined; } ? 0 : 1'.
+!!! error TS2322:       Type '0' is not assignable to type 'T extends { a?: string | undefined; } ? 0 : 1'.
+    
\ No newline at end of file
diff --git a/tests/baselines/reference/exactOptionalPropertyTypesIdentical.js b/tests/baselines/reference/exactOptionalPropertyTypesIdentical.js
new file mode 100644
index 0000000000000..e3153ce591e35
--- /dev/null
+++ b/tests/baselines/reference/exactOptionalPropertyTypesIdentical.js
@@ -0,0 +1,13 @@
+//// [tests/cases/compiler/exactOptionalPropertyTypesIdentical.ts] ////
+
+//// [exactOptionalPropertyTypesIdentical.ts]
+export let a: <T>() => T extends {a?: string} ? 0 : 1 = null!;
+export let b: <T>() => T extends {a?: string | undefined} ? 0 : 1 = a;
+
+
+//// [exactOptionalPropertyTypesIdentical.js]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.b = exports.a = void 0;
+exports.a = null;
+exports.b = exports.a;
diff --git a/tests/baselines/reference/exactOptionalPropertyTypesIdentical.symbols b/tests/baselines/reference/exactOptionalPropertyTypesIdentical.symbols
new file mode 100644
index 0000000000000..e7bbad247053d
--- /dev/null
+++ b/tests/baselines/reference/exactOptionalPropertyTypesIdentical.symbols
@@ -0,0 +1,16 @@
+//// [tests/cases/compiler/exactOptionalPropertyTypesIdentical.ts] ////
+
+=== exactOptionalPropertyTypesIdentical.ts ===
+export let a: <T>() => T extends {a?: string} ? 0 : 1 = null!;
+>a : Symbol(a, Decl(exactOptionalPropertyTypesIdentical.ts, 0, 10))
+>T : Symbol(T, Decl(exactOptionalPropertyTypesIdentical.ts, 0, 15))
+>T : Symbol(T, Decl(exactOptionalPropertyTypesIdentical.ts, 0, 15))
+>a : Symbol(a, Decl(exactOptionalPropertyTypesIdentical.ts, 0, 34))
+
+export let b: <T>() => T extends {a?: string | undefined} ? 0 : 1 = a;
+>b : Symbol(b, Decl(exactOptionalPropertyTypesIdentical.ts, 1, 10))
+>T : Symbol(T, Decl(exactOptionalPropertyTypesIdentical.ts, 1, 15))
+>T : Symbol(T, Decl(exactOptionalPropertyTypesIdentical.ts, 1, 15))
+>a : Symbol(a, Decl(exactOptionalPropertyTypesIdentical.ts, 1, 34))
+>a : Symbol(a, Decl(exactOptionalPropertyTypesIdentical.ts, 0, 10))
+
diff --git a/tests/baselines/reference/exactOptionalPropertyTypesIdentical.types b/tests/baselines/reference/exactOptionalPropertyTypesIdentical.types
new file mode 100644
index 0000000000000..ff2ea9358fd9b
--- /dev/null
+++ b/tests/baselines/reference/exactOptionalPropertyTypesIdentical.types
@@ -0,0 +1,19 @@
+//// [tests/cases/compiler/exactOptionalPropertyTypesIdentical.ts] ////
+
+=== exactOptionalPropertyTypesIdentical.ts ===
+export let a: <T>() => T extends {a?: string} ? 0 : 1 = null!;
+>a : <T>() => T extends { a?: string; } ? 0 : 1
+>  : ^ ^^^^^^^                                 
+>a : string | undefined
+>  : ^^^^^^^^^^^^^^^^^^
+>null! : never
+>      : ^^^^^
+
+export let b: <T>() => T extends {a?: string | undefined} ? 0 : 1 = a;
+>b : <T>() => T extends { a?: string | undefined; } ? 0 : 1
+>  : ^ ^^^^^^^                                             
+>a : string | undefined
+>  : ^^^^^^^^^^^^^^^^^^
+>a : <T>() => T extends { a?: string; } ? 0 : 1
+>  : ^ ^^^^^^^                                 
+
diff --git a/tests/cases/compiler/exactOptionalPropertyTypesIdentical.ts b/tests/cases/compiler/exactOptionalPropertyTypesIdentical.ts
new file mode 100644
index 0000000000000..3abb2bc66b2c9
--- /dev/null
+++ b/tests/cases/compiler/exactOptionalPropertyTypesIdentical.ts
@@ -0,0 +1,5 @@
+// @strictNullChecks: true
+// @exactOptionalPropertyTypes: true
+
+export let a: <T>() => T extends {a?: string} ? 0 : 1 = null!;
+export let b: <T>() => T extends {a?: string | undefined} ? 0 : 1 = a;

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