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Fix reverse mapped contravariant inference #21292

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Merged
merged 3 commits into from
Jan 19, 2018
Merged

Fix reverse mapped contravariant inference #21292

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5bb8d2a
Properly handle contravariant inferences in inferReverseMappedType
ahejlsberg Jan 19, 2018
f6c79a6
Add regression test
ahejlsberg Jan 19, 2018
069eac0
Accept new baselines
ahejlsberg Jan 19, 2018
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4 changes: 3 additions & 1 deletion src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -11029,7 +11029,9 @@ namespace ts {
const templateType = getTemplateTypeFromMappedType(target);
const inference = createInferenceInfo(typeParameter);
inferTypes([inference], sourceType, templateType);
return inference.candidates ? getUnionType(inference.candidates, UnionReduction.Subtype) : emptyObjectType;
return inference.candidates ? getUnionType(inference.candidates, UnionReduction.Subtype) :
inference.contraCandidates ? getCommonSubtype(inference.contraCandidates) :
emptyObjectType;
}

function getUnmatchedProperty(source: Type, target: Type, requireOptionalProperties: boolean) {
Expand Down
11 changes: 11 additions & 0 deletions tests/baselines/reference/reverseMappedContravariantInference.js
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@@ -0,0 +1,11 @@
//// [reverseMappedContravariantInference.ts]
// Repro from #21273

declare function conforms<T>(source: { [K in keyof T]: (val: T[K]) => boolean }): (value: T) => boolean;
conforms({ foo: (v: string) => false })({ foo: "hello" });


//// [reverseMappedContravariantInference.js]
"use strict";
// Repro from #21273
conforms({ foo: function (v) { return false; } })({ foo: "hello" });
21 changes: 21 additions & 0 deletions tests/baselines/reference/reverseMappedContravariantInference.symbols
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@@ -0,0 +1,21 @@
=== tests/cases/compiler/reverseMappedContravariantInference.ts ===
// Repro from #21273

declare function conforms<T>(source: { [K in keyof T]: (val: T[K]) => boolean }): (value: T) => boolean;
>conforms : Symbol(conforms, Decl(reverseMappedContravariantInference.ts, 0, 0))
>T : Symbol(T, Decl(reverseMappedContravariantInference.ts, 2, 26))
>source : Symbol(source, Decl(reverseMappedContravariantInference.ts, 2, 29))
>K : Symbol(K, Decl(reverseMappedContravariantInference.ts, 2, 40))
>T : Symbol(T, Decl(reverseMappedContravariantInference.ts, 2, 26))
>val : Symbol(val, Decl(reverseMappedContravariantInference.ts, 2, 56))
>T : Symbol(T, Decl(reverseMappedContravariantInference.ts, 2, 26))
>K : Symbol(K, Decl(reverseMappedContravariantInference.ts, 2, 40))
>value : Symbol(value, Decl(reverseMappedContravariantInference.ts, 2, 83))
>T : Symbol(T, Decl(reverseMappedContravariantInference.ts, 2, 26))

conforms({ foo: (v: string) => false })({ foo: "hello" });
>conforms : Symbol(conforms, Decl(reverseMappedContravariantInference.ts, 0, 0))
>foo : Symbol(foo, Decl(reverseMappedContravariantInference.ts, 3, 10))
>v : Symbol(v, Decl(reverseMappedContravariantInference.ts, 3, 17))
>foo : Symbol(foo, Decl(reverseMappedContravariantInference.ts, 3, 41))

28 changes: 28 additions & 0 deletions tests/baselines/reference/reverseMappedContravariantInference.types
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@@ -0,0 +1,28 @@
=== tests/cases/compiler/reverseMappedContravariantInference.ts ===
// Repro from #21273

declare function conforms<T>(source: { [K in keyof T]: (val: T[K]) => boolean }): (value: T) => boolean;
>conforms : <T>(source: { [K in keyof T]: (val: T[K]) => boolean; }) => (value: T) => boolean
>T : T
>source : { [K in keyof T]: (val: T[K]) => boolean; }
>K : K
>T : T
>val : T[K]
>T : T
>K : K
>value : T
>T : T

conforms({ foo: (v: string) => false })({ foo: "hello" });
>conforms({ foo: (v: string) => false })({ foo: "hello" }) : boolean
>conforms({ foo: (v: string) => false }) : (value: { foo: any; }) => boolean
>conforms : <T>(source: { [K in keyof T]: (val: T[K]) => boolean; }) => (value: T) => boolean
>{ foo: (v: string) => false } : { foo: (v: string) => boolean; }
>foo : (v: string) => boolean
>(v: string) => false : (v: string) => boolean
>v : string
>false : false
>{ foo: "hello" } : { foo: string; }
>foo : string
>"hello" : "hello"

6 changes: 6 additions & 0 deletions tests/cases/compiler/reverseMappedContravariantInference.ts
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@@ -0,0 +1,6 @@
// @strict: true

// Repro from #21273

declare function conforms<T>(source: { [K in keyof T]: (val: T[K]) => boolean }): (value: T) => boolean;
conforms({ foo: (v: string) => false })({ foo: "hello" });