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AndaristAndarist
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Avoid deprioritization of inferences made from mapped types with primitive type parameter constraints
1 parent 8749fb5 commit f050215

4 files changed

+183
-1
lines changed

‎src/compiler/checker.ts

+10-1
Original file line numberDiff line numberDiff line change
@@ -25059,9 +25059,18 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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applyToReturnTypes(source, target, inferFromTypes);
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}
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function hasPrimitiveMappedTypeParameterConstaint(mappedType: MappedType): boolean {
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const constraint = mappedType.typeParameter && getConstraintOfTypeParameter(mappedType.typeParameter);
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return !!(constraint && constraint.flags & TypeFlags.Primitive);
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}
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function inferFromIndexTypes(source: Type, target: Type) {
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// Inferences across mapped type index signatures are pretty much the same a inferences to homomorphic variables
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const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) ? InferencePriority.HomomorphicMappedType : 0;
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const priority = (getObjectFlags(source) & getObjectFlags(target) & ObjectFlags.Mapped) &&
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!hasPrimitiveMappedTypeParameterConstaint(source as MappedType) &&
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!hasPrimitiveMappedTypeParameterConstaint(target as MappedType) ?
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InferencePriority.HomomorphicMappedType :
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InferencePriority.None;
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const indexInfos = getIndexInfosOfType(target);
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if (isObjectTypeWithInferableIndex(source)) {
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for (const targetInfo of indexInfos) {

‎tests/baselines/reference/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.symbols

+71
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@@ -0,0 +1,71 @@
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=== tests/cases/compiler/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts ===
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// repro from https://github.com/microsoft/TypeScript/issues/54000
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function foo<T>(record: Record<string, T>, entity: T) {}
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>foo : Symbol(foo, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 0, 0))
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>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 13))
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>record : Symbol(record, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 16))
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>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
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>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 13))
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>entity : Symbol(entity, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 42))
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>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 13))
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type StringArrayRecord = Record<string, string[]>;
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>StringArrayRecord : Symbol(StringArrayRecord, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 56))
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>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
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function test() {
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>test : Symbol(test, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 4, 50))
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const working: Record<string, string[]> = {};
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>working : Symbol(working, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 7, 7))
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>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
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foo(working, []);
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>foo : Symbol(foo, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 0, 0))
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>working : Symbol(working, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 7, 7))
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const working2: StringArrayRecord = {};
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>working2 : Symbol(working2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 10, 7))
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>StringArrayRecord : Symbol(StringArrayRecord, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 2, 56))
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foo(working2, []);
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>foo : Symbol(foo, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 0, 0))
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>working2 : Symbol(working2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 10, 7))
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}
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// showcase the same behavior with index signature
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function bar<T>(record: { [k: string]: T }, entity: T) {}
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>bar : Symbol(bar, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 12, 1))
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>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 13))
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>record : Symbol(record, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 16))
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>k : Symbol(k, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 27))
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>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 13))
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>entity : Symbol(entity, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 43))
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>T : Symbol(T, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 13))
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type StringArrayIndexSignature = { [k: string]: string[] };
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>StringArrayIndexSignature : Symbol(StringArrayIndexSignature, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 57))
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>k : Symbol(k, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 18, 36))
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function test2() {
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>test2 : Symbol(test2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 18, 59))
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const working: { [k: string]: string[] } = {};
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>working : Symbol(working, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 21, 7))
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>k : Symbol(k, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 21, 20))
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bar(working, []);
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>bar : Symbol(bar, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 12, 1))
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>working : Symbol(working, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 21, 7))
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const working2: StringArrayIndexSignature = {};
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>working2 : Symbol(working2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 24, 7))
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>StringArrayIndexSignature : Symbol(StringArrayIndexSignature, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 16, 57))
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bar(working2, []);
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>bar : Symbol(bar, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 12, 1))
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>working2 : Symbol(working2, Decl(mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts, 24, 7))
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}
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‎tests/baselines/reference/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.types

+72
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@@ -0,0 +1,72 @@
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=== tests/cases/compiler/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts ===
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// repro from https://github.com/microsoft/TypeScript/issues/54000
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function foo<T>(record: Record<string, T>, entity: T) {}
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>foo : <T>(record: Record<string, T>, entity: T) => void
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>record : Record<string, T>
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>entity : T
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type StringArrayRecord = Record<string, string[]>;
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>StringArrayRecord : { [x: string]: string[]; }
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function test() {
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>test : () => void
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const working: Record<string, string[]> = {};
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>working : Record<string, string[]>
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>{} : {}
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foo(working, []);
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>foo(working, []) : void
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>foo : <T>(record: Record<string, T>, entity: T) => void
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>working : Record<string, string[]>
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>[] : never[]
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const working2: StringArrayRecord = {};
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>working2 : StringArrayRecord
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>{} : {}
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foo(working2, []);
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>foo(working2, []) : void
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>foo : <T>(record: Record<string, T>, entity: T) => void
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>working2 : StringArrayRecord
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>[] : never[]
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}
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// showcase the same behavior with index signature
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function bar<T>(record: { [k: string]: T }, entity: T) {}
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>bar : <T>(record: { [k: string]: T; }, entity: T) => void
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>record : { [k: string]: T; }
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>k : string
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>entity : T
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type StringArrayIndexSignature = { [k: string]: string[] };
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>StringArrayIndexSignature : { [k: string]: string[]; }
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>k : string
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function test2() {
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>test2 : () => void
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const working: { [k: string]: string[] } = {};
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>working : { [k: string]: string[]; }
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>k : string
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>{} : {}
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bar(working, []);
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>bar(working, []) : void
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>bar : <T>(record: { [k: string]: T; }, entity: T) => void
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>working : { [k: string]: string[]; }
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>[] : never[]
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const working2: StringArrayIndexSignature = {};
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>working2 : StringArrayIndexSignature
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>{} : {}
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bar(working2, []);
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>bar(working2, []) : void
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>bar : <T>(record: { [k: string]: T; }, entity: T) => void
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>working2 : StringArrayIndexSignature
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>[] : never[]
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}
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‎tests/cases/compiler/mappedTypeWithPrimitiveTypeParameterConstraintInferencePriority.ts

+30
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@@ -0,0 +1,30 @@
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// @strict: true
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// @noEmit: true
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// repro from https://github.com/microsoft/TypeScript/issues/54000
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function foo<T>(record: Record<string, T>, entity: T) {}
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type StringArrayRecord = Record<string, string[]>;
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function test() {
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const working: Record<string, string[]> = {};
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foo(working, []);
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const working2: StringArrayRecord = {};
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foo(working2, []);
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}
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// showcase the same behavior with index signature
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function bar<T>(record: { [k: string]: T }, entity: T) {}
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type StringArrayIndexSignature = { [k: string]: string[] };
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function test2() {
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const working: { [k: string]: string[] } = {};
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bar(working, []);
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const working2: StringArrayIndexSignature = {};
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bar(working2, []);
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}

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