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Merge pull request microsoft#8821 from Microsoft/intersectionTypeInference
Improve intersection type inference
2 parents f5a52ee + 6a27289 commit b3f167f

5 files changed

Lines changed: 102 additions & 5 deletions

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‎src/compiler/checker.ts‎

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@@ -7158,11 +7158,10 @@ namespace ts {
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inferFromTypes(source, t);
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}
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}
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// Next, if target is a union type containing a single naked type parameter, make a
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// secondary inference to that type parameter. We don't do this for intersection types
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// because in a target type like Foo & T we don't know how which parts of the source type
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// should be matched by Foo and which should be inferred to T.
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if (target.flags & TypeFlags.Union && typeParameterCount === 1) {
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// Next, if target containings a single naked type parameter, make a secondary inference to that type
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// parameter. This gives meaningful results for union types in co-variant positions and intersection
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// types in contra-variant positions (such as callback parameters).
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if (typeParameterCount === 1) {
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inferiority++;
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inferFromTypes(source, typeParameter);
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inferiority--;

‎tests/baselines/reference/intersectionTypeInference1.js‎

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//// [intersectionTypeInference1.ts]
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// Repro from #8801
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function alert(s: string) {}
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const parameterFn = (props:{store:string}) => alert(props.store)
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const brokenFunction = <OwnProps>(f: (p: {dispatch: number} & OwnProps) => void) => (o: OwnProps) => o
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export const Form3 = brokenFunction(parameterFn)({store: "hello"})
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//// [intersectionTypeInference1.js]
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// Repro from #8801
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"use strict";
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function alert(s) { }
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var parameterFn = function (props) { return alert(props.store); };
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var brokenFunction = function (f) { return function (o) { return o; }; };
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exports.Form3 = brokenFunction(parameterFn)({ store: "hello" });

‎tests/baselines/reference/intersectionTypeInference1.symbols‎

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=== tests/cases/compiler/intersectionTypeInference1.ts ===
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// Repro from #8801
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function alert(s: string) {}
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>alert : Symbol(alert, Decl(intersectionTypeInference1.ts, 0, 0))
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>s : Symbol(s, Decl(intersectionTypeInference1.ts, 2, 15))
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const parameterFn = (props:{store:string}) => alert(props.store)
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>parameterFn : Symbol(parameterFn, Decl(intersectionTypeInference1.ts, 4, 5))
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>props : Symbol(props, Decl(intersectionTypeInference1.ts, 4, 21))
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>store : Symbol(store, Decl(intersectionTypeInference1.ts, 4, 28))
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>alert : Symbol(alert, Decl(intersectionTypeInference1.ts, 0, 0))
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>props.store : Symbol(store, Decl(intersectionTypeInference1.ts, 4, 28))
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>props : Symbol(props, Decl(intersectionTypeInference1.ts, 4, 21))
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>store : Symbol(store, Decl(intersectionTypeInference1.ts, 4, 28))
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const brokenFunction = <OwnProps>(f: (p: {dispatch: number} & OwnProps) => void) => (o: OwnProps) => o
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>brokenFunction : Symbol(brokenFunction, Decl(intersectionTypeInference1.ts, 5, 5))
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>OwnProps : Symbol(OwnProps, Decl(intersectionTypeInference1.ts, 5, 24))
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>f : Symbol(f, Decl(intersectionTypeInference1.ts, 5, 34))
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>p : Symbol(p, Decl(intersectionTypeInference1.ts, 5, 38))
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>dispatch : Symbol(dispatch, Decl(intersectionTypeInference1.ts, 5, 42))
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>OwnProps : Symbol(OwnProps, Decl(intersectionTypeInference1.ts, 5, 24))
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>o : Symbol(o, Decl(intersectionTypeInference1.ts, 5, 85))
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>OwnProps : Symbol(OwnProps, Decl(intersectionTypeInference1.ts, 5, 24))
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>o : Symbol(o, Decl(intersectionTypeInference1.ts, 5, 85))
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export const Form3 = brokenFunction(parameterFn)({store: "hello"})
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>Form3 : Symbol(Form3, Decl(intersectionTypeInference1.ts, 6, 12))
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>brokenFunction : Symbol(brokenFunction, Decl(intersectionTypeInference1.ts, 5, 5))
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>parameterFn : Symbol(parameterFn, Decl(intersectionTypeInference1.ts, 4, 5))
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>store : Symbol(store, Decl(intersectionTypeInference1.ts, 6, 50))
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‎tests/baselines/reference/intersectionTypeInference1.types‎

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=== tests/cases/compiler/intersectionTypeInference1.ts ===
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// Repro from #8801
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function alert(s: string) {}
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>alert : (s: string) => void
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>s : string
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const parameterFn = (props:{store:string}) => alert(props.store)
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>parameterFn : (props: { store: string; }) => void
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>(props:{store:string}) => alert(props.store) : (props: { store: string; }) => void
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>props : { store: string; }
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>store : string
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>alert(props.store) : void
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>alert : (s: string) => void
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>props.store : string
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>props : { store: string; }
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>store : string
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const brokenFunction = <OwnProps>(f: (p: {dispatch: number} & OwnProps) => void) => (o: OwnProps) => o
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>brokenFunction : <OwnProps>(f: (p: { dispatch: number; } & OwnProps) => void) => (o: OwnProps) => OwnProps
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><OwnProps>(f: (p: {dispatch: number} & OwnProps) => void) => (o: OwnProps) => o : <OwnProps>(f: (p: { dispatch: number; } & OwnProps) => void) => (o: OwnProps) => OwnProps
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>OwnProps : OwnProps
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>f : (p: { dispatch: number; } & OwnProps) => void
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>p : { dispatch: number; } & OwnProps
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>dispatch : number
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>OwnProps : OwnProps
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>(o: OwnProps) => o : (o: OwnProps) => OwnProps
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>o : OwnProps
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>OwnProps : OwnProps
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>o : OwnProps
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export const Form3 = brokenFunction(parameterFn)({store: "hello"})
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>Form3 : { store: string; }
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>brokenFunction(parameterFn)({store: "hello"}) : { store: string; }
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>brokenFunction(parameterFn) : (o: { store: string; }) => { store: string; }
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>brokenFunction : <OwnProps>(f: (p: { dispatch: number; } & OwnProps) => void) => (o: OwnProps) => OwnProps
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>parameterFn : (props: { store: string; }) => void
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>{store: "hello"} : { store: string; }
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>store : string
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>"hello" : string
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‎tests/cases/compiler/intersectionTypeInference1.ts‎

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// Repro from #8801
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function alert(s: string) {}
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const parameterFn = (props:{store:string}) => alert(props.store)
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const brokenFunction = <OwnProps>(f: (p: {dispatch: number} & OwnProps) => void) => (o: OwnProps) => o
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export const Form3 = brokenFunction(parameterFn)({store: "hello"})

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