From 9ad4be713179403583ab8c9d17ddbb6c4aa15544 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mateusz=20Burzy=C5=84ski?= <mateuszburzynski@gmail.com>
Date: Tue, 4 Mar 2025 22:52:00 +0100
Subject: [PATCH] Properly discriminate by pattern literal types in
 `isTypeInvalidDueToUnionDiscriminant`

---
 src/compiler/checker.ts                       |  2 +-
 .../completionsDiscriminatedUnion2.ts         | 19 +++++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)
 create mode 100644 tests/cases/fourslash/completionsDiscriminatedUnion2.ts

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index caab75c99fa8a..4583dca0806ee 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -14453,7 +14453,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             const nameType = property.name && (isJsxNamespacedName(property.name) ? getStringLiteralType(getTextOfJsxAttributeName(property.name)) : getLiteralTypeFromPropertyName(property.name));
             const name = nameType && isTypeUsableAsPropertyName(nameType) ? getPropertyNameFromType(nameType) : undefined;
             const expected = name === undefined ? undefined : getTypeOfPropertyOfType(contextualType, name);
-            return !!expected && isLiteralType(expected) && !isTypeAssignableTo(getTypeOfNode(property), expected);
+            return !!expected && (isLiteralType(expected) || isPatternLiteralType(expected)) && !isTypeAssignableTo(getTypeOfNode(property), expected);
         });
     }
 
diff --git a/tests/cases/fourslash/completionsDiscriminatedUnion2.ts b/tests/cases/fourslash/completionsDiscriminatedUnion2.ts
new file mode 100644
index 0000000000000..2167b8a706499
--- /dev/null
+++ b/tests/cases/fourslash/completionsDiscriminatedUnion2.ts
@@ -0,0 +1,19 @@
+/// <reference path="fourslash.ts" />
+
+// @strict: true
+
+//// type A = {
+////   id: `A:${string}`;
+////   a: number;
+//// };
+////
+//// type B = {
+////   id: `B:${string}`;
+////   b: number;
+//// };
+////
+//// function foo<T extends A | B>(item: T): void {}
+////
+//// foo({ id: "B:", /**/ });
+
+verify.completions({ marker: "", exact: ["b"] });