Avoid deprioritization of inferences made from mapped types with prim…

…itive type parameter constraints
microsoft · Apr 25, 2023 · f050215 · f050215
1 parent 8749fb5
commit f050215
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Showing 4 changed files with 183 additions and 1 deletion.
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -25059,9 +25059,18 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             applyToReturnTypes(source, target, inferFromTypes);
         }
 
+        function hasPrimitiveMappedTypeParameterConstaint(mappedType: MappedType): boolean {
+            const constraint = mappedType.typeParameter && getConstraintOfTypeParameter(mappedType.typeParameter);
+            return !!(constraint && constraint.flags & TypeFlags.Primitive);
+        }
+
         function inferFromIndexTypes(source: Type, target: Type) {
             // Inferences across mapped type index signatures are pretty much the same a inferences to homomorphic variables
-            const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) ? InferencePriority.HomomorphicMappedType : 0;
+            const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) &&
+                !hasPrimitiveMappedTypeParameterConstaint(source as MappedType) &&
+                !hasPrimitiveMappedTypeParameterConstaint(target as MappedType) ?
+                    InferencePriority.HomomorphicMappedType :
+                    InferencePriority.None;
             const indexInfos = getIndexInfosOfType(target);
             if (isObjectTypeWithInferableIndex(source)) {
                 for (const targetInfo of indexInfos) {

diff --git a/...selines/reference/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.symbols b/...selines/reference/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.symbols
@@ -0,0 +1,71 @@
+=== tests/cases/compiler/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts ===
+// repro from https://github.com/microsoft/TypeScript/issues/54000
+
+function foo<T>(record: Record<string, T>, entity: T) {}
+>foo : Symbol(foo, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 0, 0))
+>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 13))
+>record : Symbol(record, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 16))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 13))
+>entity : Symbol(entity, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 42))
+>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 13))
+
+type StringArrayRecord = Record<string, string[]>;
+>StringArrayRecord : Symbol(StringArrayRecord, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 56))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+
+function test() {
+>test : Symbol(test, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 4, 50))
+
+  const working: Record<string, string[]> = {};
+>working : Symbol(working, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 7, 7))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+
+  foo(working, []);
+>foo : Symbol(foo, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 0, 0))
+>working : Symbol(working, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 7, 7))
+
+  const working2: StringArrayRecord = {};
+>working2 : Symbol(working2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 10, 7))
+>StringArrayRecord : Symbol(StringArrayRecord, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 56))
+
+  foo(working2, []);
+>foo : Symbol(foo, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 0, 0))
+>working2 : Symbol(working2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 10, 7))
+}
+
+// showcase the same behavior with index signature
+
+function bar<T>(record: { [k: string]: T }, entity: T) {}
+>bar : Symbol(bar, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 12, 1))
+>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 13))
+>record : Symbol(record, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 16))
+>k : Symbol(k, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 27))
+>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 13))
+>entity : Symbol(entity, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 43))
+>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 13))
+
+type StringArrayIndexSignature = { [k: string]: string[] };
+>StringArrayIndexSignature : Symbol(StringArrayIndexSignature, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 57))
+>k : Symbol(k, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 18, 36))
+
+function test2() {
+>test2 : Symbol(test2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 18, 59))
+
+  const working: { [k: string]: string[] } = {};
+>working : Symbol(working, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 21, 7))
+>k : Symbol(k, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 21, 20))
+
+  bar(working, []);
+>bar : Symbol(bar, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 12, 1))
+>working : Symbol(working, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 21, 7))
+
+  const working2: StringArrayIndexSignature = {};
+>working2 : Symbol(working2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 24, 7))
+>StringArrayIndexSignature : Symbol(StringArrayIndexSignature, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 57))
+
+  bar(working2, []);
+>bar : Symbol(bar, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 12, 1))
+>working2 : Symbol(working2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 24, 7))
+}
+
diff --git a/...baselines/reference/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.types b/...baselines/reference/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.types
@@ -0,0 +1,72 @@
+=== tests/cases/compiler/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts ===
+// repro from https://github.com/microsoft/TypeScript/issues/54000
+
+function foo<T>(record: Record<string, T>, entity: T) {}
+>foo : <T>(record: Record<string, T>, entity: T) => void
+>record : Record<string, T>
+>entity : T
+
+type StringArrayRecord = Record<string, string[]>;
+>StringArrayRecord : { [x: string]: string[]; }
+
+function test() {
+>test : () => void
+
+  const working: Record<string, string[]> = {};
+>working : Record<string, string[]>
+>{} : {}
+
+  foo(working, []);
+>foo(working, []) : void
+>foo : <T>(record: Record<string, T>, entity: T) => void
+>working : Record<string, string[]>
+>[] : never[]
+
+  const working2: StringArrayRecord = {};
+>working2 : StringArrayRecord
+>{} : {}
+
+  foo(working2, []);
+>foo(working2, []) : void
+>foo : <T>(record: Record<string, T>, entity: T) => void
+>working2 : StringArrayRecord
+>[] : never[]
+}
+
+// showcase the same behavior with index signature
+
+function bar<T>(record: { [k: string]: T }, entity: T) {}
+>bar : <T>(record: { [k: string]: T; }, entity: T) => void
+>record : { [k: string]: T; }
+>k : string
+>entity : T
+
+type StringArrayIndexSignature = { [k: string]: string[] };
+>StringArrayIndexSignature : { [k: string]: string[]; }
+>k : string
+
+function test2() {
+>test2 : () => void
+
+  const working: { [k: string]: string[] } = {};
+>working : { [k: string]: string[]; }
+>k : string
+>{} : {}
+
+  bar(working, []);
+>bar(working, []) : void
+>bar : <T>(record: { [k: string]: T; }, entity: T) => void
+>working : { [k: string]: string[]; }
+>[] : never[]
+
+  const working2: StringArrayIndexSignature = {};
+>working2 : StringArrayIndexSignature
+>{} : {}
+
+  bar(working2, []);
+>bar(working2, []) : void
+>bar : <T>(record: { [k: string]: T; }, entity: T) => void
+>working2 : StringArrayIndexSignature
+>[] : never[]
+}
+
diff --git a/tests/cases/compiler/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts b/tests/cases/compiler/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts
@@ -0,0 +1,30 @@
+// @strict: true
+// @noEmit: true
+
+// repro from https://github.com/microsoft/TypeScript/issues/54000
+
+function foo<T>(record: Record<string, T>, entity: T) {}
+
+type StringArrayRecord = Record<string, string[]>;
+
+function test() {
+  const working: Record<string, string[]> = {};
+  foo(working, []);
+
+  const working2: StringArrayRecord = {};
+  foo(working2, []);
+}
+
+// showcase the same behavior with index signature
+
+function bar<T>(record: { [k: string]: T }, entity: T) {}
+
+type StringArrayIndexSignature = { [k: string]: string[] };
+
+function test2() {
+  const working: { [k: string]: string[] } = {};
+  bar(working, []);
+
+  const working2: StringArrayIndexSignature = {};
+  bar(working2, []);
+}