Test:infer from related types only

Author: sandersn

tests/baselines/reference/doNotInferUnrelatedTypes.js

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+//// [doNotInferUnrelatedTypes.ts]
+// #16709
+declare function dearray<T>(ara: ReadonlyArray<T>): T;
+type LiteralType = "foo" | "bar";
+declare var alt: Array<LiteralType>;
+
+let foo: LiteralType = dearray(alt);
+
+
+//// [doNotInferUnrelatedTypes.js]
+var foo = dearray(alt);

tests/baselines/reference/doNotInferUnrelatedTypes.symbols

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+=== tests/cases/compiler/doNotInferUnrelatedTypes.ts ===
+// #16709
+declare function dearray<T>(ara: ReadonlyArray<T>): T;
+>dearray : Symbol(dearray, Decl(doNotInferUnrelatedTypes.ts, 0, 0))
+>T : Symbol(T, Decl(doNotInferUnrelatedTypes.ts, 1, 25))
+>ara : Symbol(ara, Decl(doNotInferUnrelatedTypes.ts, 1, 28))
+>ReadonlyArray : Symbol(ReadonlyArray, Decl(lib.d.ts, --, --))
+>T : Symbol(T, Decl(doNotInferUnrelatedTypes.ts, 1, 25))
+>T : Symbol(T, Decl(doNotInferUnrelatedTypes.ts, 1, 25))
+
+type LiteralType = "foo" | "bar";
+>LiteralType : Symbol(LiteralType, Decl(doNotInferUnrelatedTypes.ts, 1, 54))
+
+declare var alt: Array<LiteralType>;
+>alt : Symbol(alt, Decl(doNotInferUnrelatedTypes.ts, 3, 11))
+>Array : Symbol(Array, Decl(lib.d.ts, --, --), Decl(lib.d.ts, --, --))
+>LiteralType : Symbol(LiteralType, Decl(doNotInferUnrelatedTypes.ts, 1, 54))
+
+let foo: LiteralType = dearray(alt);
+>foo : Symbol(foo, Decl(doNotInferUnrelatedTypes.ts, 5, 3))
+>LiteralType : Symbol(LiteralType, Decl(doNotInferUnrelatedTypes.ts, 1, 54))
+>dearray : Symbol(dearray, Decl(doNotInferUnrelatedTypes.ts, 0, 0))
+>alt : Symbol(alt, Decl(doNotInferUnrelatedTypes.ts, 3, 11))
+

tests/baselines/reference/doNotInferUnrelatedTypes.types

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+=== tests/cases/compiler/doNotInferUnrelatedTypes.ts ===
+// #16709
+declare function dearray<T>(ara: ReadonlyArray<T>): T;
+>dearray : <T>(ara: ReadonlyArray<T>) => T
+>T : T
+>ara : ReadonlyArray<T>
+>ReadonlyArray : ReadonlyArray<T>
+>T : T
+>T : T
+
+type LiteralType = "foo" | "bar";
+>LiteralType : LiteralType
+
+declare var alt: Array<LiteralType>;
+>alt : LiteralType[]
+>Array : T[]
+>LiteralType : LiteralType
+
+let foo: LiteralType = dearray(alt);
+>foo : LiteralType
+>LiteralType : LiteralType
+>dearray(alt) : LiteralType
+>dearray : <T>(ara: ReadonlyArray<T>) => T
+>alt : LiteralType[]
+

tests/cases/compiler/doNotInferUnrelatedTypes.ts

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+// #16709
+declare function dearray<T>(ara: ReadonlyArray<T>): T;
+type LiteralType = "foo" | "bar";
+declare var alt: Array<LiteralType>;
+
+let foo: LiteralType = dearray(alt);