Collect contravariant-only inference candidates from shorter annotated functions

Author: Andarist

src/compiler/checker.ts

@@ -35379,6 +35379,12 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                         assignNonContextualParameterTypes(signature);
                     }
                 }
+                else if (contextualSignature && !node.typeParameters && contextualSignature.parameters.length > node.parameters.length) {
+                    const inferenceContext = getInferenceContext(node);
+                    if (checkMode && checkMode & CheckMode.Inferential) {
+                        inferFromAnnotatedParameters(signature, contextualSignature, inferenceContext!);
+                    }
+                }
                 if (contextualSignature && !getReturnTypeFromAnnotation(node) && !signature.resolvedReturnType) {
                     const returnType = getReturnTypeFromBody(node, checkMode);
                     if (!signature.resolvedReturnType) {

tests/baselines/reference/contravariantOnlyInferenceFromAnnotatedFunction.symbols

@@ -0,0 +1,57 @@
+=== tests/cases/compiler/contravariantOnlyInferenceFromAnnotatedFunction.ts ===
+// repro from #52580
+
+type Funcs<A, B extends Record<string, unknown>> = {
+>Funcs : Symbol(Funcs, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 0, 0))
+>A : Symbol(A, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 2, 11))
+>B : Symbol(B, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 2, 13))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+
+  [K in keyof B]: {
+>K : Symbol(K, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 3, 3))
+>B : Symbol(B, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 2, 13))
+
+    fn: (a: A, b: B) => void;
+>fn : Symbol(fn, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 3, 19))
+>a : Symbol(a, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 4, 9))
+>A : Symbol(A, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 2, 11))
+>b : Symbol(b, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 4, 14))
+>B : Symbol(B, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 2, 13))
+
+    thing: B[K];
+>thing : Symbol(thing, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 4, 29))
+>B : Symbol(B, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 2, 13))
+>K : Symbol(K, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 3, 3))
+
+  };
+}
+
+declare function foo<A, B extends Record<string, unknown>>(fns: Funcs<A, B>): [A, B]
+>foo : Symbol(foo, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 7, 1))
+>A : Symbol(A, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 9, 21))
+>B : Symbol(B, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 9, 23))
+>Record : Symbol(Record, Decl(lib.es5.d.ts, --, --))
+>fns : Symbol(fns, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 9, 59))
+>Funcs : Symbol(Funcs, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 0, 0))
+>A : Symbol(A, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 9, 21))
+>B : Symbol(B, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 9, 23))
+>A : Symbol(A, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 9, 21))
+>B : Symbol(B, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 9, 23))
+
+const result = foo({
+>result : Symbol(result, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 11, 5))
+>foo : Symbol(foo, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 7, 1))
+
+  bar: {
+>bar : Symbol(bar, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 11, 20))
+
+    fn: (a: string) => {},
+>fn : Symbol(fn, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 12, 8))
+>a : Symbol(a, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 13, 9))
+
+    thing: 'asd',
+>thing : Symbol(thing, Decl(contravariantOnlyInferenceFromAnnotatedFunction.ts, 13, 26))
+
+  },
+});
+

tests/baselines/reference/contravariantOnlyInferenceFromAnnotatedFunction.types

@@ -0,0 +1,44 @@
+=== tests/cases/compiler/contravariantOnlyInferenceFromAnnotatedFunction.ts ===
+// repro from #52580
+
+type Funcs<A, B extends Record<string, unknown>> = {
+>Funcs : Funcs<A, B>
+
+  [K in keyof B]: {
+    fn: (a: A, b: B) => void;
+>fn : (a: A, b: B) => void
+>a : A
+>b : B
+
+    thing: B[K];
+>thing : B[K]
+
+  };
+}
+
+declare function foo<A, B extends Record<string, unknown>>(fns: Funcs<A, B>): [A, B]
+>foo : <A, B extends Record<string, unknown>>(fns: Funcs<A, B>) => [A, B]
+>fns : Funcs<A, B>
+
+const result = foo({
+>result : [string, { bar: string; }]
+>foo({  bar: {    fn: (a: string) => {},    thing: 'asd',  },}) : [string, { bar: string; }]
+>foo : <A, B extends Record<string, unknown>>(fns: Funcs<A, B>) => [A, B]
+>{  bar: {    fn: (a: string) => {},    thing: 'asd',  },} : { bar: { fn: (a: string) => void; thing: string; }; }
+
+  bar: {
+>bar : { fn: (a: string) => void; thing: string; }
+>{    fn: (a: string) => {},    thing: 'asd',  } : { fn: (a: string) => void; thing: string; }
+
+    fn: (a: string) => {},
+>fn : (a: string) => void
+>(a: string) => {} : (a: string) => void
+>a : string
+
+    thing: 'asd',
+>thing : string
+>'asd' : "asd"
+
+  },
+});
+

tests/cases/compiler/contravariantOnlyInferenceFromAnnotatedFunction.ts

@@ -0,0 +1,20 @@
+// @strict: true
+// @noEmit: true
+
+// repro from #52580
+
+type Funcs<A, B extends Record<string, unknown>> = {
+  [K in keyof B]: {
+    fn: (a: A, b: B) => void;
+    thing: B[K];
+  };
+}
+
+declare function foo<A, B extends Record<string, unknown>>(fns: Funcs<A, B>): [A, B]
+
+const result = foo({
+  bar: {
+    fn: (a: string) => {},
+    thing: 'asd',
+  },
+});