add regression test

Author: gabritto

tests/baselines/reference/mappedTypeInferenceFromApparentType.symbols

@@ -0,0 +1,44 @@
+//// [tests/cases/compiler/mappedTypeInferenceFromApparentType.ts] ////
+
+=== mappedTypeInferenceFromApparentType.ts ===
+type Obj = {
+>Obj : Symbol(Obj, Decl(mappedTypeInferenceFromApparentType.ts, 0, 0))
+
+    [s: string]: number;
+>s : Symbol(s, Decl(mappedTypeInferenceFromApparentType.ts, 1, 5))
+
+    [u: symbol]: boolean;
+>u : Symbol(u, Decl(mappedTypeInferenceFromApparentType.ts, 2, 5))
+
+};
+
+type foo = <T>(target: { [K in keyof T]: T[K] }) => void;
+>foo : Symbol(foo, Decl(mappedTypeInferenceFromApparentType.ts, 3, 2))
+>T : Symbol(T, Decl(mappedTypeInferenceFromApparentType.ts, 5, 12))
+>target : Symbol(target, Decl(mappedTypeInferenceFromApparentType.ts, 5, 15))
+>K : Symbol(K, Decl(mappedTypeInferenceFromApparentType.ts, 5, 26))
+>T : Symbol(T, Decl(mappedTypeInferenceFromApparentType.ts, 5, 12))
+>T : Symbol(T, Decl(mappedTypeInferenceFromApparentType.ts, 5, 12))
+>K : Symbol(K, Decl(mappedTypeInferenceFromApparentType.ts, 5, 26))
+
+type bar = <U extends string[]>(source: { [K in keyof U]: Obj[K] }) => void;
+>bar : Symbol(bar, Decl(mappedTypeInferenceFromApparentType.ts, 5, 57))
+>U : Symbol(U, Decl(mappedTypeInferenceFromApparentType.ts, 6, 12))
+>source : Symbol(source, Decl(mappedTypeInferenceFromApparentType.ts, 6, 32))
+>K : Symbol(K, Decl(mappedTypeInferenceFromApparentType.ts, 6, 43))
+>U : Symbol(U, Decl(mappedTypeInferenceFromApparentType.ts, 6, 12))
+>Obj : Symbol(Obj, Decl(mappedTypeInferenceFromApparentType.ts, 0, 0))
+>K : Symbol(K, Decl(mappedTypeInferenceFromApparentType.ts, 6, 43))
+
+declare let f: foo;
+>f : Symbol(f, Decl(mappedTypeInferenceFromApparentType.ts, 8, 11))
+>foo : Symbol(foo, Decl(mappedTypeInferenceFromApparentType.ts, 3, 2))
+
+declare let b: bar;
+>b : Symbol(b, Decl(mappedTypeInferenceFromApparentType.ts, 9, 11))
+>bar : Symbol(bar, Decl(mappedTypeInferenceFromApparentType.ts, 5, 57))
+
+b = f;
+>b : Symbol(b, Decl(mappedTypeInferenceFromApparentType.ts, 9, 11))
+>f : Symbol(f, Decl(mappedTypeInferenceFromApparentType.ts, 8, 11))
+

tests/baselines/reference/mappedTypeInferenceFromApparentType.types

@@ -0,0 +1,33 @@
+//// [tests/cases/compiler/mappedTypeInferenceFromApparentType.ts] ////
+
+=== mappedTypeInferenceFromApparentType.ts ===
+type Obj = {
+>Obj : { [s: string]: number; [u: symbol]: boolean; }
+
+    [s: string]: number;
+>s : string
+
+    [u: symbol]: boolean;
+>u : symbol
+
+};
+
+type foo = <T>(target: { [K in keyof T]: T[K] }) => void;
+>foo : <T>(target: { [K in keyof T]: T[K]; }) => void
+>target : { [K in keyof T]: T[K]; }
+
+type bar = <U extends string[]>(source: { [K in keyof U]: Obj[K] }) => void;
+>bar : <U extends string[]>(source: { [K in keyof U]: Obj[K]; }) => void
+>source : { [K in keyof U]: Obj[K]; }
+
+declare let f: foo;
+>f : foo
+
+declare let b: bar;
+>b : bar
+
+b = f;
+>b = f : foo
+>b : bar
+>f : foo
+

tests/cases/compiler/mappedTypeInferenceFromApparentType.ts

@@ -0,0 +1,14 @@
+// @strict: true
+// @noEmit: true
+
+type Obj = {
+    [s: string]: number;
+    [u: symbol]: boolean;
+};
+
+type foo = <T>(target: { [K in keyof T]: T[K] }) => void;
+type bar = <U extends string[]>(source: { [K in keyof U]: Obj[K] }) => void;
+
+declare let f: foo;
+declare let b: bar;
+b = f;