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fix: silentNeverType leak in contextual parameter types coming from anon... #63519

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Arnav Nagzirkar (arnavnagzirkar) wants to merge 2 commits into from
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fix: silentNeverType leak in contextual parameter types coming from anon... #63519

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0772415
fix: `silentNeverType` leak in contextual parameter types coming from…
Jun 1, 2026
7b17227
Merge branch 'main' into fix-62345
arnavnagzirkar Jun 1, 2026
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5 changes: 5 additions & 0 deletions src/compiler/checker.ts
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Expand Up @@ -20784,6 +20784,11 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
target.objectFlags & ObjectFlags.Mapped ? instantiateMappedType(target as MappedType, newMapper, newAliasSymbol, newAliasTypeArguments) :
instantiateAnonymousType(target, newMapper, newAliasSymbol, newAliasTypeArguments);
target.instantiations.set(id, result); // Set cached result early in case we recursively invoke instantiation while eagerly computing type variable visibility below
// For anonymous types without aliasTypeArguments, propagate NonInferrableType from the type arguments.
// For types with aliasTypeArguments, instantiateAnonymousType already propagates this from aliasTypeArguments.
if (!(target.objectFlags & (ObjectFlags.Reference | ObjectFlags.Mapped)) && !newAliasTypeArguments) {
(result as ObjectFlagsType).objectFlags |= getPropagatingFlagsOfTypes(typeArguments) & ObjectFlags.NonInferrableType;
}
const resultObjectFlags = getObjectFlags(result);
if (result.flags & TypeFlags.ObjectFlagsType && !(resultObjectFlags & ObjectFlags.CouldContainTypeVariablesComputed)) {
const resultCouldContainTypeVariables = some(typeArguments, couldContainTypeVariables); // one of the input type arguments might be or contain the result
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94 changes: 94 additions & 0 deletions tests/baselines/reference/silentNeverAnonymousTypeNonInferrable.errors.txt
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silentNeverAnonymousTypeNonInferrable.ts(17,22): error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<{ default: unknown; }>'.
Type 'P<unknown>' is not assignable to type 'P<{ default: unknown; }>'.
Type 'unknown' is not assignable to type '{ default: unknown; }'.
silentNeverAnonymousTypeNonInferrable.ts(27,22): error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<WithDefault<unknown>>'.
Type 'P<unknown>' is not assignable to type 'P<WithDefault<unknown>>'.
Type 'unknown' is not assignable to type 'WithDefault<unknown>'.
silentNeverAnonymousTypeNonInferrable.ts(35,22): error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<[unknown]>'.
Type 'P<unknown>' is not assignable to type 'P<[unknown]>'.
Type 'unknown' is not assignable to type '[unknown]'.
silentNeverAnonymousTypeNonInferrable.ts(43,22): error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<{ default: { prop: unknown; }; }>'.
Type 'P<unknown>' is not assignable to type 'P<{ default: { prop: unknown; }; }>'.
Type 'unknown' is not assignable to type '{ default: { prop: unknown; }; }'.
silentNeverAnonymousTypeNonInferrable.ts(51,22): error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<{ default: [unknown]; }>'.
Type 'P<unknown>' is not assignable to type 'P<{ default: [unknown]; }>'.
Type 'unknown' is not assignable to type '{ default: [unknown]; }'.


==== silentNeverAnonymousTypeNonInferrable.ts (5 errors) ====
// Repro from GH#62345 - silentNeverType should not leak from anonymous non-aliased object type instantiations.
// All foo1-foo5 should consistently produce errors with resolve typed as (value: unknown) => void,
// not just foo2/foo3 which use type aliases or tuples.

interface P<T> {
then: (onfulfilled: (value: T) => unknown) => unknown;
}

interface PConstructor {
new <T>(executor: (resolve: (value: T) => void) => void): P<T>;
}

declare var P: PConstructor;

declare function foo1<T>(x: () => P<{ default: T }>): T;

const result1 = foo1(() => {
~~~~~~~
!!! error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<{ default: unknown; }>'.
!!! error TS2345: Type 'P<unknown>' is not assignable to type 'P<{ default: unknown; }>'.
!!! error TS2345: Type 'unknown' is not assignable to type '{ default: unknown; }'.
return new P((resolve) => {
resolve;
});
});

type WithDefault<T> = { default: T };

declare function foo2<T>(x: () => P<WithDefault<T>>): T;

const result2 = foo2(() => {
~~~~~~~
!!! error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<WithDefault<unknown>>'.
!!! error TS2345: Type 'P<unknown>' is not assignable to type 'P<WithDefault<unknown>>'.
!!! error TS2345: Type 'unknown' is not assignable to type 'WithDefault<unknown>'.
return new P((resolve) => {
resolve;
});
});

declare function foo3<T>(x: () => P<[T]>): T;

const result3 = foo3(() => {
~~~~~~~
!!! error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<[unknown]>'.
!!! error TS2345: Type 'P<unknown>' is not assignable to type 'P<[unknown]>'.
!!! error TS2345: Type 'unknown' is not assignable to type '[unknown]'.
return new P((resolve) => {
resolve;
});
});

declare function foo4<T>(x: () => P<{ default: { prop: T } }>): T;

const result4 = foo4(() => {
~~~~~~~
!!! error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<{ default: { prop: unknown; }; }>'.
!!! error TS2345: Type 'P<unknown>' is not assignable to type 'P<{ default: { prop: unknown; }; }>'.
!!! error TS2345: Type 'unknown' is not assignable to type '{ default: { prop: unknown; }; }'.
return new P((resolve) => {
resolve;
});
});

declare function foo5<T>(x: () => P<{ default: [T] }>): T;

const result5 = foo5(() => {
~~~~~~~
!!! error TS2345: Argument of type '() => P<unknown>' is not assignable to parameter of type '() => P<{ default: [unknown]; }>'.
!!! error TS2345: Type 'P<unknown>' is not assignable to type 'P<{ default: [unknown]; }>'.
!!! error TS2345: Type 'unknown' is not assignable to type '{ default: [unknown]; }'.
return new P((resolve) => {
resolve;
});
});

90 changes: 90 additions & 0 deletions tests/baselines/reference/silentNeverAnonymousTypeNonInferrable.js
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//// [tests/cases/compiler/silentNeverAnonymousTypeNonInferrable.ts] ////

//// [silentNeverAnonymousTypeNonInferrable.ts]
// Repro from GH#62345 - silentNeverType should not leak from anonymous non-aliased object type instantiations.
// All foo1-foo5 should consistently produce errors with resolve typed as (value: unknown) => void,
// not just foo2/foo3 which use type aliases or tuples.

interface P<T> {
then: (onfulfilled: (value: T) => unknown) => unknown;
}

interface PConstructor {
new <T>(executor: (resolve: (value: T) => void) => void): P<T>;
}

declare var P: PConstructor;

declare function foo1<T>(x: () => P<{ default: T }>): T;

const result1 = foo1(() => {
return new P((resolve) => {
resolve;
});
});

type WithDefault<T> = { default: T };

declare function foo2<T>(x: () => P<WithDefault<T>>): T;

const result2 = foo2(() => {
return new P((resolve) => {
resolve;
});
});

declare function foo3<T>(x: () => P<[T]>): T;

const result3 = foo3(() => {
return new P((resolve) => {
resolve;
});
});

declare function foo4<T>(x: () => P<{ default: { prop: T } }>): T;

const result4 = foo4(() => {
return new P((resolve) => {
resolve;
});
});

declare function foo5<T>(x: () => P<{ default: [T] }>): T;

const result5 = foo5(() => {
return new P((resolve) => {
resolve;
});
});


//// [silentNeverAnonymousTypeNonInferrable.js]
"use strict";
// Repro from GH#62345 - silentNeverType should not leak from anonymous non-aliased object type instantiations.
// All foo1-foo5 should consistently produce errors with resolve typed as (value: unknown) => void,
// not just foo2/foo3 which use type aliases or tuples.
const result1 = foo1(() => {
return new P((resolve) => {
resolve;
});
});
const result2 = foo2(() => {
return new P((resolve) => {
resolve;
});
});
const result3 = foo3(() => {
return new P((resolve) => {
resolve;
});
});
const result4 = foo4(() => {
return new P((resolve) => {
resolve;
});
});
const result5 = foo5(() => {
return new P((resolve) => {
resolve;
});
});
156 changes: 156 additions & 0 deletions tests/baselines/reference/silentNeverAnonymousTypeNonInferrable.symbols
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//// [tests/cases/compiler/silentNeverAnonymousTypeNonInferrable.ts] ////

=== silentNeverAnonymousTypeNonInferrable.ts ===
// Repro from GH#62345 - silentNeverType should not leak from anonymous non-aliased object type instantiations.
// All foo1-foo5 should consistently produce errors with resolve typed as (value: unknown) => void,
// not just foo2/foo3 which use type aliases or tuples.

interface P<T> {
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 4, 12))

then: (onfulfilled: (value: T) => unknown) => unknown;
>then : Symbol(P.then, Decl(silentNeverAnonymousTypeNonInferrable.ts, 4, 16))
>onfulfilled : Symbol(onfulfilled, Decl(silentNeverAnonymousTypeNonInferrable.ts, 5, 11))
>value : Symbol(value, Decl(silentNeverAnonymousTypeNonInferrable.ts, 5, 25))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 4, 12))
}

interface PConstructor {
>PConstructor : Symbol(PConstructor, Decl(silentNeverAnonymousTypeNonInferrable.ts, 6, 1))

new <T>(executor: (resolve: (value: T) => void) => void): P<T>;
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 9, 9))
>executor : Symbol(executor, Decl(silentNeverAnonymousTypeNonInferrable.ts, 9, 12))
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 9, 23))
>value : Symbol(value, Decl(silentNeverAnonymousTypeNonInferrable.ts, 9, 33))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 9, 9))
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 9, 9))
}

declare var P: PConstructor;
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>PConstructor : Symbol(PConstructor, Decl(silentNeverAnonymousTypeNonInferrable.ts, 6, 1))

declare function foo1<T>(x: () => P<{ default: T }>): T;
>foo1 : Symbol(foo1, Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 28))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 14, 22))
>x : Symbol(x, Decl(silentNeverAnonymousTypeNonInferrable.ts, 14, 25))
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>default : Symbol(default, Decl(silentNeverAnonymousTypeNonInferrable.ts, 14, 37))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 14, 22))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 14, 22))

const result1 = foo1(() => {
>result1 : Symbol(result1, Decl(silentNeverAnonymousTypeNonInferrable.ts, 16, 5))
>foo1 : Symbol(foo1, Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 28))

return new P((resolve) => {
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 17, 18))

resolve;
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 17, 18))

});
});

type WithDefault<T> = { default: T };
>WithDefault : Symbol(WithDefault, Decl(silentNeverAnonymousTypeNonInferrable.ts, 20, 3))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 22, 17))
>default : Symbol(default, Decl(silentNeverAnonymousTypeNonInferrable.ts, 22, 23))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 22, 17))

declare function foo2<T>(x: () => P<WithDefault<T>>): T;
>foo2 : Symbol(foo2, Decl(silentNeverAnonymousTypeNonInferrable.ts, 22, 37))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 24, 22))
>x : Symbol(x, Decl(silentNeverAnonymousTypeNonInferrable.ts, 24, 25))
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>WithDefault : Symbol(WithDefault, Decl(silentNeverAnonymousTypeNonInferrable.ts, 20, 3))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 24, 22))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 24, 22))

const result2 = foo2(() => {
>result2 : Symbol(result2, Decl(silentNeverAnonymousTypeNonInferrable.ts, 26, 5))
>foo2 : Symbol(foo2, Decl(silentNeverAnonymousTypeNonInferrable.ts, 22, 37))

return new P((resolve) => {
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 27, 18))

resolve;
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 27, 18))

});
});

declare function foo3<T>(x: () => P<[T]>): T;
>foo3 : Symbol(foo3, Decl(silentNeverAnonymousTypeNonInferrable.ts, 30, 3))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 32, 22))
>x : Symbol(x, Decl(silentNeverAnonymousTypeNonInferrable.ts, 32, 25))
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 32, 22))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 32, 22))

const result3 = foo3(() => {
>result3 : Symbol(result3, Decl(silentNeverAnonymousTypeNonInferrable.ts, 34, 5))
>foo3 : Symbol(foo3, Decl(silentNeverAnonymousTypeNonInferrable.ts, 30, 3))

return new P((resolve) => {
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 35, 18))

resolve;
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 35, 18))

});
});

declare function foo4<T>(x: () => P<{ default: { prop: T } }>): T;
>foo4 : Symbol(foo4, Decl(silentNeverAnonymousTypeNonInferrable.ts, 38, 3))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 40, 22))
>x : Symbol(x, Decl(silentNeverAnonymousTypeNonInferrable.ts, 40, 25))
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>default : Symbol(default, Decl(silentNeverAnonymousTypeNonInferrable.ts, 40, 37))
>prop : Symbol(prop, Decl(silentNeverAnonymousTypeNonInferrable.ts, 40, 48))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 40, 22))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 40, 22))

const result4 = foo4(() => {
>result4 : Symbol(result4, Decl(silentNeverAnonymousTypeNonInferrable.ts, 42, 5))
>foo4 : Symbol(foo4, Decl(silentNeverAnonymousTypeNonInferrable.ts, 38, 3))

return new P((resolve) => {
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 43, 18))

resolve;
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 43, 18))

});
});

declare function foo5<T>(x: () => P<{ default: [T] }>): T;
>foo5 : Symbol(foo5, Decl(silentNeverAnonymousTypeNonInferrable.ts, 46, 3))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 48, 22))
>x : Symbol(x, Decl(silentNeverAnonymousTypeNonInferrable.ts, 48, 25))
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>default : Symbol(default, Decl(silentNeverAnonymousTypeNonInferrable.ts, 48, 37))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 48, 22))
>T : Symbol(T, Decl(silentNeverAnonymousTypeNonInferrable.ts, 48, 22))

const result5 = foo5(() => {
>result5 : Symbol(result5, Decl(silentNeverAnonymousTypeNonInferrable.ts, 50, 5))
>foo5 : Symbol(foo5, Decl(silentNeverAnonymousTypeNonInferrable.ts, 46, 3))

return new P((resolve) => {
>P : Symbol(P, Decl(silentNeverAnonymousTypeNonInferrable.ts, 0, 0), Decl(silentNeverAnonymousTypeNonInferrable.ts, 12, 11))
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 51, 18))

resolve;
>resolve : Symbol(resolve, Decl(silentNeverAnonymousTypeNonInferrable.ts, 51, 18))

});
});

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