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Assign contextual parameter types to functions with type parameters #61792

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94709a6
Assign contextual parameter types to functions with type parameters
Andarist Jun 1, 2025
1f037fb
Merge remote-tracking branch 'origin/main' into contextual-parameter-…
Andarist Jun 25, 2025
b97406f
assign and resolve some contextual parameter types late
Andarist Jun 26, 2025
f6d53bd
Revert "assign and resolve some contextual parameter types late"
Andarist Jun 30, 2025
3db0dc6
Just assign those contextual parameter types for now, without any att…
Andarist Jun 30, 2025
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2 changes: 1 addition & 1 deletion src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -21025,7 +21025,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
}

function hasContextSensitiveReturnExpression(node: FunctionLikeDeclaration) {
if (node.typeParameters || getEffectiveReturnTypeNode(node) || !node.body) {
if (getEffectiveReturnTypeNode(node) || !node.body) {
return false;
}
if (node.body.kind !== SyntaxKind.Block) {
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21 changes: 9 additions & 12 deletions src/compiler/utilities.ts
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Expand Up @@ -10783,20 +10783,17 @@ export function getContainingNodeArray(node: Node): NodeArray<Node> | undefined

/** @internal */
export function hasContextSensitiveParameters(node: FunctionLikeDeclaration): boolean {
// Functions with type parameters are not context sensitive.
if (!node.typeParameters) {
// Functions with any parameters that lack type annotations are context sensitive.
if (some(node.parameters, p => !getEffectiveTypeAnnotationNode(p))) {
// Functions with any parameters that lack type annotations are context sensitive.
if (some(node.parameters, p => !getEffectiveTypeAnnotationNode(p))) {
return true;
}
if (node.kind !== SyntaxKind.ArrowFunction) {
// If the first parameter is not an explicit 'this' parameter, then the function has
// an implicit 'this' parameter which is subject to contextual typing.
const parameter = firstOrUndefined(node.parameters);
if (!(parameter && parameterIsThisKeyword(parameter))) {
return true;
}
if (node.kind !== SyntaxKind.ArrowFunction) {
// If the first parameter is not an explicit 'this' parameter, then the function has
// an implicit 'this' parameter which is subject to contextual typing.
const parameter = firstOrUndefined(node.parameters);
if (!(parameter && parameterIsThisKeyword(parameter))) {
return true;
}
}
}
return false;
}
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89 changes: 89 additions & 0 deletions tests/baselines/reference/contextualTypingGenericFunction2.js
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@@ -0,0 +1,89 @@
//// [tests/cases/compiler/contextualTypingGenericFunction2.ts] ////

//// [contextualTypingGenericFunction2.ts]
// https://github.com/microsoft/TypeScript/issues/61791

declare const fn1: <T, Args extends Array<any>, Ret>(
self: T,
body: (this: T, ...args: Args) => Ret,
) => (...args: Args) => Ret;

export const ok1 = fn1({ message: "foo" }, function (n: number) {
this.message;
});

export const ok2 = fn1({ message: "foo" }, function <N>(n: N) {
this.message;
});

declare const fn2: <Args extends Array<any>, Ret>(
body: (first: string, ...args: Args) => Ret,
) => (...args: Args) => Ret;

export const ok3 = fn2(function <N>(first, n: N) {});

declare const fn3: <Args extends Array<any>, Ret>(
body: (...args: Args) => (arg: string) => Ret,
) => (...args: Args) => Ret;

export const ok4 = fn3(function <N>(n: N) {
return (arg) => {
return 10
}
});

declare function fn4<T, P>(config: {
context: T;
callback: (params: P) => (context: T, params: P) => number;
}): (params: P) => number;

export const ok5 = fn4({
context: 1,
callback: <T,>(params: T) => {
return (a, b) => a + 1;
},
});

declare const fnGen1: <T, Args extends Array<any>, Ret>(
self: T,
body: (this: T, ...args: Args) => Generator<any, Ret, never>,
) => (...args: Args) => Ret;

export const ok6 = fnGen1({ message: "foo" }, function* (n: number) {
this.message;
});

export const ok7 = fnGen1({ message: "foo" }, function* <N>(n: N) {
this.message;
});




//// [contextualTypingGenericFunction2.d.ts]
export declare const ok1: (n: number) => void;
export declare const ok2: (n: any) => void;
export declare const ok3: <N>(n: N) => void;
export declare const ok4: <N>(n: N) => number;
export declare const ok5: (params: T) => number;
export declare const ok6: (n: number) => void;
export declare const ok7: (n: any) => void;


//// [DtsFileErrors]


contextualTypingGenericFunction2.d.ts(5,36): error TS2304: Cannot find name 'T'.


==== contextualTypingGenericFunction2.d.ts (1 errors) ====
export declare const ok1: (n: number) => void;
export declare const ok2: (n: any) => void;
export declare const ok3: <N>(n: N) => void;
export declare const ok4: <N>(n: N) => number;
export declare const ok5: (params: T) => number;
~
!!! error TS2304: Cannot find name 'T'.
export declare const ok6: (n: number) => void;
export declare const ok7: (n: any) => void;

212 changes: 212 additions & 0 deletions tests/baselines/reference/contextualTypingGenericFunction2.symbols
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@@ -0,0 +1,212 @@
//// [tests/cases/compiler/contextualTypingGenericFunction2.ts] ////

=== contextualTypingGenericFunction2.ts ===
// https://github.com/microsoft/TypeScript/issues/61791

declare const fn1: <T, Args extends Array<any>, Ret>(
>fn1 : Symbol(fn1, Decl(contextualTypingGenericFunction2.ts, 2, 13))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 2, 20))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 2, 22))
>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 4 more)
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 2, 47))

self: T,
>self : Symbol(self, Decl(contextualTypingGenericFunction2.ts, 2, 53))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 2, 20))

body: (this: T, ...args: Args) => Ret,
>body : Symbol(body, Decl(contextualTypingGenericFunction2.ts, 3, 10))
>this : Symbol(this, Decl(contextualTypingGenericFunction2.ts, 4, 9))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 2, 20))
>args : Symbol(args, Decl(contextualTypingGenericFunction2.ts, 4, 17))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 2, 22))
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 2, 47))

) => (...args: Args) => Ret;
>args : Symbol(args, Decl(contextualTypingGenericFunction2.ts, 5, 6))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 2, 22))
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 2, 47))

export const ok1 = fn1({ message: "foo" }, function (n: number) {
>ok1 : Symbol(ok1, Decl(contextualTypingGenericFunction2.ts, 7, 12))
>fn1 : Symbol(fn1, Decl(contextualTypingGenericFunction2.ts, 2, 13))
>message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 7, 24))
>n : Symbol(n, Decl(contextualTypingGenericFunction2.ts, 7, 53))

this.message;
>this.message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 7, 24))
>this : Symbol(this, Decl(contextualTypingGenericFunction2.ts, 4, 9))
>message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 7, 24))

});

export const ok2 = fn1({ message: "foo" }, function <N>(n: N) {
>ok2 : Symbol(ok2, Decl(contextualTypingGenericFunction2.ts, 11, 12))
>fn1 : Symbol(fn1, Decl(contextualTypingGenericFunction2.ts, 2, 13))
>message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 11, 24))
>N : Symbol(N, Decl(contextualTypingGenericFunction2.ts, 11, 53))
>n : Symbol(n, Decl(contextualTypingGenericFunction2.ts, 11, 56))
>N : Symbol(N, Decl(contextualTypingGenericFunction2.ts, 11, 53))

this.message;
>this.message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 11, 24))
>this : Symbol(this, Decl(contextualTypingGenericFunction2.ts, 4, 9))
>message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 11, 24))

});

declare const fn2: <Args extends Array<any>, Ret>(
>fn2 : Symbol(fn2, Decl(contextualTypingGenericFunction2.ts, 15, 13))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 15, 20))
>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 4 more)
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 15, 44))

body: (first: string, ...args: Args) => Ret,
>body : Symbol(body, Decl(contextualTypingGenericFunction2.ts, 15, 50))
>first : Symbol(first, Decl(contextualTypingGenericFunction2.ts, 16, 9))
>args : Symbol(args, Decl(contextualTypingGenericFunction2.ts, 16, 23))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 15, 20))
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 15, 44))

) => (...args: Args) => Ret;
>args : Symbol(args, Decl(contextualTypingGenericFunction2.ts, 17, 6))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 15, 20))
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 15, 44))

export const ok3 = fn2(function <N>(first, n: N) {});
>ok3 : Symbol(ok3, Decl(contextualTypingGenericFunction2.ts, 19, 12))
>fn2 : Symbol(fn2, Decl(contextualTypingGenericFunction2.ts, 15, 13))
>N : Symbol(N, Decl(contextualTypingGenericFunction2.ts, 19, 33))
>first : Symbol(first, Decl(contextualTypingGenericFunction2.ts, 19, 36))
>n : Symbol(n, Decl(contextualTypingGenericFunction2.ts, 19, 42))
>N : Symbol(N, Decl(contextualTypingGenericFunction2.ts, 19, 33))

declare const fn3: <Args extends Array<any>, Ret>(
>fn3 : Symbol(fn3, Decl(contextualTypingGenericFunction2.ts, 21, 13))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 21, 20))
>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 4 more)
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 21, 44))

body: (...args: Args) => (arg: string) => Ret,
>body : Symbol(body, Decl(contextualTypingGenericFunction2.ts, 21, 50))
>args : Symbol(args, Decl(contextualTypingGenericFunction2.ts, 22, 9))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 21, 20))
>arg : Symbol(arg, Decl(contextualTypingGenericFunction2.ts, 22, 28))
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 21, 44))

) => (...args: Args) => Ret;
>args : Symbol(args, Decl(contextualTypingGenericFunction2.ts, 23, 6))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 21, 20))
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 21, 44))

export const ok4 = fn3(function <N>(n: N) {
>ok4 : Symbol(ok4, Decl(contextualTypingGenericFunction2.ts, 25, 12))
>fn3 : Symbol(fn3, Decl(contextualTypingGenericFunction2.ts, 21, 13))
>N : Symbol(N, Decl(contextualTypingGenericFunction2.ts, 25, 33))
>n : Symbol(n, Decl(contextualTypingGenericFunction2.ts, 25, 36))
>N : Symbol(N, Decl(contextualTypingGenericFunction2.ts, 25, 33))

return (arg) => {
>arg : Symbol(arg, Decl(contextualTypingGenericFunction2.ts, 26, 12))

return 10
}
});

declare function fn4<T, P>(config: {
>fn4 : Symbol(fn4, Decl(contextualTypingGenericFunction2.ts, 29, 3))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 31, 21))
>P : Symbol(P, Decl(contextualTypingGenericFunction2.ts, 31, 23))
>config : Symbol(config, Decl(contextualTypingGenericFunction2.ts, 31, 27))

context: T;
>context : Symbol(context, Decl(contextualTypingGenericFunction2.ts, 31, 36))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 31, 21))

callback: (params: P) => (context: T, params: P) => number;
>callback : Symbol(callback, Decl(contextualTypingGenericFunction2.ts, 32, 13))
>params : Symbol(params, Decl(contextualTypingGenericFunction2.ts, 33, 13))
>P : Symbol(P, Decl(contextualTypingGenericFunction2.ts, 31, 23))
>context : Symbol(context, Decl(contextualTypingGenericFunction2.ts, 33, 28))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 31, 21))
>params : Symbol(params, Decl(contextualTypingGenericFunction2.ts, 33, 39))
>P : Symbol(P, Decl(contextualTypingGenericFunction2.ts, 31, 23))

}): (params: P) => number;
>params : Symbol(params, Decl(contextualTypingGenericFunction2.ts, 34, 5))
>P : Symbol(P, Decl(contextualTypingGenericFunction2.ts, 31, 23))

export const ok5 = fn4({
>ok5 : Symbol(ok5, Decl(contextualTypingGenericFunction2.ts, 36, 12))
>fn4 : Symbol(fn4, Decl(contextualTypingGenericFunction2.ts, 29, 3))

context: 1,
>context : Symbol(context, Decl(contextualTypingGenericFunction2.ts, 36, 24))

callback: <T,>(params: T) => {
>callback : Symbol(callback, Decl(contextualTypingGenericFunction2.ts, 37, 13))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 38, 13))
>params : Symbol(params, Decl(contextualTypingGenericFunction2.ts, 38, 17))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 38, 13))

return (a, b) => a + 1;
>a : Symbol(a, Decl(contextualTypingGenericFunction2.ts, 39, 12))
>b : Symbol(b, Decl(contextualTypingGenericFunction2.ts, 39, 14))
>a : Symbol(a, Decl(contextualTypingGenericFunction2.ts, 39, 12))

},
});

declare const fnGen1: <T, Args extends Array<any>, Ret>(
>fnGen1 : Symbol(fnGen1, Decl(contextualTypingGenericFunction2.ts, 43, 13))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 43, 23))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 43, 25))
>Array : Symbol(Array, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --) ... and 4 more)
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 43, 50))

self: T,
>self : Symbol(self, Decl(contextualTypingGenericFunction2.ts, 43, 56))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 43, 23))

body: (this: T, ...args: Args) => Generator<any, Ret, never>,
>body : Symbol(body, Decl(contextualTypingGenericFunction2.ts, 44, 10))
>this : Symbol(this, Decl(contextualTypingGenericFunction2.ts, 45, 9))
>T : Symbol(T, Decl(contextualTypingGenericFunction2.ts, 43, 23))
>args : Symbol(args, Decl(contextualTypingGenericFunction2.ts, 45, 17))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 43, 25))
>Generator : Symbol(Generator, Decl(lib.es2015.generator.d.ts, --, --))
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 43, 50))

) => (...args: Args) => Ret;
>args : Symbol(args, Decl(contextualTypingGenericFunction2.ts, 46, 6))
>Args : Symbol(Args, Decl(contextualTypingGenericFunction2.ts, 43, 25))
>Ret : Symbol(Ret, Decl(contextualTypingGenericFunction2.ts, 43, 50))

export const ok6 = fnGen1({ message: "foo" }, function* (n: number) {
>ok6 : Symbol(ok6, Decl(contextualTypingGenericFunction2.ts, 48, 12))
>fnGen1 : Symbol(fnGen1, Decl(contextualTypingGenericFunction2.ts, 43, 13))
>message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 48, 27))
>n : Symbol(n, Decl(contextualTypingGenericFunction2.ts, 48, 57))

this.message;
>this.message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 48, 27))
>this : Symbol(this, Decl(contextualTypingGenericFunction2.ts, 45, 9))
>message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 48, 27))

});

export const ok7 = fnGen1({ message: "foo" }, function* <N>(n: N) {
>ok7 : Symbol(ok7, Decl(contextualTypingGenericFunction2.ts, 52, 12))
>fnGen1 : Symbol(fnGen1, Decl(contextualTypingGenericFunction2.ts, 43, 13))
>message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 52, 27))
>N : Symbol(N, Decl(contextualTypingGenericFunction2.ts, 52, 57))
>n : Symbol(n, Decl(contextualTypingGenericFunction2.ts, 52, 60))
>N : Symbol(N, Decl(contextualTypingGenericFunction2.ts, 52, 57))

this.message;
>this.message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 52, 27))
>this : Symbol(this, Decl(contextualTypingGenericFunction2.ts, 45, 9))
>message : Symbol(message, Decl(contextualTypingGenericFunction2.ts, 52, 27))

});

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