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Improve logic that chooses co- vs. contra-variant inferences (#57909)
1 parent ed81ca6 commit a71841c

7 files changed

+305
-5
lines changed

‎src/compiler/checker.ts

+7-5
Original file line numberDiff line numberDiff line change
@@ -26811,15 +26811,17 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
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const inferredContravariantType = inference.contraCandidates ? getContravariantInference(inference) : undefined;
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if (inferredCovariantType || inferredContravariantType) {
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// If we have both co- and contra-variant inferences, we prefer the co-variant inference if it is not 'never',
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// all co-variant inferences are subtypes of it (i.e. it isn't one of a conflicting set of candidates), it is
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// a subtype of some contra-variant inference, and no other type parameter is constrained to this type parameter
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// all co-variant inferences are assignable to it (i.e. it isn't one of a conflicting set of candidates), it is
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// assignable to some contra-variant inference, and no other type parameter is constrained to this type parameter
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// and has inferences that would conflict. Otherwise, we prefer the contra-variant inference.
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// Similarly ignore co-variant `any` inference when both are available as almost everything is assignable to it
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// and it would spoil the overall inference.
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const preferCovariantType = inferredCovariantType && (!inferredContravariantType ||
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!(inferredCovariantType.flags & TypeFlags.Never) &&
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some(inference.contraCandidates, t => isTypeSubtypeOf(inferredCovariantType, t)) &&
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!(inferredCovariantType.flags & (TypeFlags.Never | TypeFlags.Any)) &&
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some(inference.contraCandidates, t => isTypeAssignableTo(inferredCovariantType, t)) &&
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every(context.inferences, other =>
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other !== inference && getConstraintOfTypeParameter(other.typeParameter) !== inference.typeParameter ||
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every(other.candidates, t => isTypeSubtypeOf(t, inferredCovariantType))));
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every(other.candidates, t => isTypeAssignableTo(t, inferredCovariantType))));
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inferredType = preferCovariantType ? inferredCovariantType : inferredContravariantType;
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fallbackType = preferCovariantType ? inferredContravariantType : inferredCovariantType;
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}

‎tests/baselines/reference/coAndContraVariantInferences7.symbols

+77
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@@ -0,0 +1,77 @@
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//// [tests/cases/compiler/coAndContraVariantInferences7.ts] ////
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=== coAndContraVariantInferences7.ts ===
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type Request<TSchema extends Schema> = {
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>Request : Symbol(Request, Decl(coAndContraVariantInferences7.ts, 0, 0))
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>TSchema : Symbol(TSchema, Decl(coAndContraVariantInferences7.ts, 0, 13))
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>Schema : Symbol(Schema, Decl(coAndContraVariantInferences7.ts, 2, 2))
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query: TSchema["query"];
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>query : Symbol(query, Decl(coAndContraVariantInferences7.ts, 0, 40))
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>TSchema : Symbol(TSchema, Decl(coAndContraVariantInferences7.ts, 0, 13))
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};
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type Schema = { query?: unknown; body?: unknown };
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>Schema : Symbol(Schema, Decl(coAndContraVariantInferences7.ts, 2, 2))
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>query : Symbol(query, Decl(coAndContraVariantInferences7.ts, 4, 15))
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>body : Symbol(body, Decl(coAndContraVariantInferences7.ts, 4, 32))
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declare function route<TSchema extends Schema>(obj: {
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>route : Symbol(route, Decl(coAndContraVariantInferences7.ts, 4, 50))
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>TSchema : Symbol(TSchema, Decl(coAndContraVariantInferences7.ts, 6, 23))
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>Schema : Symbol(Schema, Decl(coAndContraVariantInferences7.ts, 2, 2))
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>obj : Symbol(obj, Decl(coAndContraVariantInferences7.ts, 6, 47))
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pre: (a: TSchema) => void;
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>pre : Symbol(pre, Decl(coAndContraVariantInferences7.ts, 6, 53))
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>a : Symbol(a, Decl(coAndContraVariantInferences7.ts, 7, 8))
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>TSchema : Symbol(TSchema, Decl(coAndContraVariantInferences7.ts, 6, 23))
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schema: TSchema;
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>schema : Symbol(schema, Decl(coAndContraVariantInferences7.ts, 7, 28))
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>TSchema : Symbol(TSchema, Decl(coAndContraVariantInferences7.ts, 6, 23))
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handle: (req: Request<TSchema>) => void;
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>handle : Symbol(handle, Decl(coAndContraVariantInferences7.ts, 8, 18))
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>req : Symbol(req, Decl(coAndContraVariantInferences7.ts, 9, 11))
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>Request : Symbol(Request, Decl(coAndContraVariantInferences7.ts, 0, 0))
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>TSchema : Symbol(TSchema, Decl(coAndContraVariantInferences7.ts, 6, 23))
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}): void;
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const validate = (_: { query?: unknown; body?: unknown }) => {};
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>validate : Symbol(validate, Decl(coAndContraVariantInferences7.ts, 12, 5))
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>_ : Symbol(_, Decl(coAndContraVariantInferences7.ts, 12, 18))
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>query : Symbol(query, Decl(coAndContraVariantInferences7.ts, 12, 22))
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>body : Symbol(body, Decl(coAndContraVariantInferences7.ts, 12, 39))
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route({
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>route : Symbol(route, Decl(coAndContraVariantInferences7.ts, 4, 50))
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pre: validate,
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>pre : Symbol(pre, Decl(coAndContraVariantInferences7.ts, 14, 7))
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>validate : Symbol(validate, Decl(coAndContraVariantInferences7.ts, 12, 5))
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schema: {
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>schema : Symbol(schema, Decl(coAndContraVariantInferences7.ts, 15, 16))
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query: "",
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>query : Symbol(query, Decl(coAndContraVariantInferences7.ts, 16, 11))
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},
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handle: (req) => {
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>handle : Symbol(handle, Decl(coAndContraVariantInferences7.ts, 18, 4))
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>req : Symbol(req, Decl(coAndContraVariantInferences7.ts, 19, 11))
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const test: string = req.query;
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>test : Symbol(test, Decl(coAndContraVariantInferences7.ts, 20, 9))
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>req.query : Symbol(query, Decl(coAndContraVariantInferences7.ts, 0, 40))
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>req : Symbol(req, Decl(coAndContraVariantInferences7.ts, 19, 11))
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>query : Symbol(query, Decl(coAndContraVariantInferences7.ts, 0, 40))
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},
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});
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export {};
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‎tests/baselines/reference/coAndContraVariantInferences7.types

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@@ -0,0 +1,107 @@
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//// [tests/cases/compiler/coAndContraVariantInferences7.ts] ////
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=== coAndContraVariantInferences7.ts ===
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type Request<TSchema extends Schema> = {
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>Request : Request<TSchema>
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> : ^^^^^^^^^^^^^^^^
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query: TSchema["query"];
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>query : TSchema["query"]
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> : ^^^^^^^^^^^^^^^^
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};
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type Schema = { query?: unknown; body?: unknown };
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>Schema : Schema
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> : ^^^^^^
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>query : unknown
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> : ^^^^^^^
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>body : unknown
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> : ^^^^^^^
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declare function route<TSchema extends Schema>(obj: {
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>route : <TSchema extends Schema>(obj: { pre: (a: TSchema) => void; schema: TSchema; handle: (req: Request<TSchema>) => void; }) => void
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> : ^ ^^^^^^^^^ ^^ ^^ ^^^^^
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>obj : { pre: (a: TSchema) => void; schema: TSchema; handle: (req: Request<TSchema>) => void; }
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> : ^^^^^^^ ^^^^^^^^^^ ^^^^^^^^^^ ^^^
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pre: (a: TSchema) => void;
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>pre : (a: TSchema) => void
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> : ^ ^^ ^^^^^
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>a : TSchema
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> : ^^^^^^^
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schema: TSchema;
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>schema : TSchema
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> : ^^^^^^^
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handle: (req: Request<TSchema>) => void;
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>handle : (req: Request<TSchema>) => void
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> : ^ ^^ ^^^^^
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>req : Request<TSchema>
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> : ^^^^^^^^^^^^^^^^
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}): void;
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const validate = (_: { query?: unknown; body?: unknown }) => {};
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>validate : (_: { query?: unknown; body?: unknown; }) => void
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> : ^ ^^ ^^^^^^^^^
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>(_: { query?: unknown; body?: unknown }) => {} : (_: { query?: unknown; body?: unknown; }) => void
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> : ^ ^^ ^^^^^^^^^
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>_ : { query?: unknown; body?: unknown; }
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> : ^^^^^^^^^^ ^^^^^^^^^ ^^^
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>query : unknown
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> : ^^^^^^^
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>body : unknown
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> : ^^^^^^^
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route({
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>route({ pre: validate, schema: { query: "", }, handle: (req) => { const test: string = req.query; },}) : void
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> : ^^^^
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>route : <TSchema extends Schema>(obj: { pre: (a: TSchema) => void; schema: TSchema; handle: (req: Request<TSchema>) => void; }) => void
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> : ^ ^^^^^^^^^ ^^ ^^ ^^^^^
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>{ pre: validate, schema: { query: "", }, handle: (req) => { const test: string = req.query; },} : { pre: (_: { query?: unknown; body?: unknown; }) => void; schema: { query: string; }; handle: (req: Request<{ query: string; }>) => void; }
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> : ^^^^^^^^ ^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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pre: validate,
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>pre : (_: { query?: unknown; body?: unknown; }) => void
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> : ^ ^^ ^^^^^^^^^
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>validate : (_: { query?: unknown; body?: unknown; }) => void
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> : ^ ^^ ^^^^^^^^^
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schema: {
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>schema : { query: string; }
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> : ^^^^^^^^^^^^^^^^^^
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>{ query: "", } : { query: string; }
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> : ^^^^^^^^^^^^^^^^^^
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query: "",
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>query : string
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> : ^^^^^^
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>"" : ""
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> : ^^
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},
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handle: (req) => {
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>handle : (req: Request<{ query: string; }>) => void
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> : ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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>(req) => { const test: string = req.query; } : (req: Request<{ query: string; }>) => void
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> : ^ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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>req : Request<{ query: string; }>
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> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^
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const test: string = req.query;
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>test : string
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> : ^^^^^^
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>req.query : string
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> : ^^^^^^
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>req : Request<{ query: string; }>
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> : ^^^^^^^^^^^^^^^^^^^^^^^^^^^
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>query : string
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> : ^^^^^^
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},
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});
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export {};
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‎tests/baselines/reference/coAndContraVariantInferences8.symbols

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@@ -0,0 +1,29 @@
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//// [tests/cases/compiler/coAndContraVariantInferences8.ts] ////
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=== coAndContraVariantInferences8.ts ===
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// https://github.com/microsoft/TypeScript/issues/58468
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declare const fn: (() => void) | ((a: number) => void);
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>fn : Symbol(fn, Decl(coAndContraVariantInferences8.ts, 2, 13))
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>a : Symbol(a, Decl(coAndContraVariantInferences8.ts, 2, 35))
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declare const x: number;
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>x : Symbol(x, Decl(coAndContraVariantInferences8.ts, 4, 13))
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declare const y: any;
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>y : Symbol(y, Decl(coAndContraVariantInferences8.ts, 5, 13))
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fn.call(null, x);
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>fn.call : Symbol(CallableFunction.call, Decl(lib.es5.d.ts, --, --))
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>fn : Symbol(fn, Decl(coAndContraVariantInferences8.ts, 2, 13))
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>call : Symbol(CallableFunction.call, Decl(lib.es5.d.ts, --, --))
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>x : Symbol(x, Decl(coAndContraVariantInferences8.ts, 4, 13))
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fn.call(null, y);
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>fn.call : Symbol(CallableFunction.call, Decl(lib.es5.d.ts, --, --))
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>fn : Symbol(fn, Decl(coAndContraVariantInferences8.ts, 2, 13))
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>call : Symbol(CallableFunction.call, Decl(lib.es5.d.ts, --, --))
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>y : Symbol(y, Decl(coAndContraVariantInferences8.ts, 5, 13))
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export {};
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‎tests/baselines/reference/coAndContraVariantInferences8.types

+43
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//// [tests/cases/compiler/coAndContraVariantInferences8.ts] ////
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=== coAndContraVariantInferences8.ts ===
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// https://github.com/microsoft/TypeScript/issues/58468
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declare const fn: (() => void) | ((a: number) => void);
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>fn : (() => void) | ((a: number) => void)
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> : ^^^^^^^ ^^^^^^ ^^ ^^^^^ ^
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>a : number
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> : ^^^^^^
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declare const x: number;
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>x : number
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> : ^^^^^^
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declare const y: any;
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>y : any
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fn.call(null, x);
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>fn.call(null, x) : void
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> : ^^^^
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>fn.call : <T, A extends any[], R>(this: (this: T, ...args: A) => R, thisArg: T, ...args: A) => R
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> : ^ ^^ ^^^^^^^^^ ^^ ^^ ^^ ^^ ^^ ^^^^^ ^^ ^^^^^
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>fn : (() => void) | ((a: number) => void)
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> : ^^^^^^^ ^^^^^^ ^^ ^^^^^ ^
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>call : <T, A extends any[], R>(this: (this: T, ...args: A) => R, thisArg: T, ...args: A) => R
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> : ^ ^^ ^^^^^^^^^ ^^ ^^ ^^ ^^ ^^ ^^^^^ ^^ ^^^^^
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>x : number
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> : ^^^^^^
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fn.call(null, y);
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>fn.call(null, y) : void
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> : ^^^^
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>fn.call : <T, A extends any[], R>(this: (this: T, ...args: A) => R, thisArg: T, ...args: A) => R
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> : ^ ^^ ^^^^^^^^^ ^^ ^^ ^^ ^^ ^^ ^^^^^ ^^ ^^^^^
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>fn : (() => void) | ((a: number) => void)
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> : ^^^^^^^ ^^^^^^ ^^ ^^^^^ ^
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>call : <T, A extends any[], R>(this: (this: T, ...args: A) => R, thisArg: T, ...args: A) => R
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> : ^ ^^ ^^^^^^^^^ ^^ ^^ ^^ ^^ ^^ ^^^^^ ^^ ^^^^^
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>y : any
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export {};
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‎tests/cases/compiler/coAndContraVariantInferences7.ts

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// @strict: true
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// @noEmit: true
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type Request<TSchema extends Schema> = {
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query: TSchema["query"];
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};
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type Schema = { query?: unknown; body?: unknown };
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declare function route<TSchema extends Schema>(obj: {
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pre: (a: TSchema) => void;
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schema: TSchema;
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handle: (req: Request<TSchema>) => void;
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}): void;
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const validate = (_: { query?: unknown; body?: unknown }) => {};
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route({
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pre: validate,
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schema: {
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query: "",
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},
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handle: (req) => {
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const test: string = req.query;
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},
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});
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export {};

‎tests/cases/compiler/coAndContraVariantInferences8.ts

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// @strict: true
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// @noEmit: true
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// https://github.com/microsoft/TypeScript/issues/58468
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declare const fn: (() => void) | ((a: number) => void);
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declare const x: number;
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declare const y: any;
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fn.call(null, x);
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fn.call(null, y);
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export {};

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