be4b814a4c
* Treat never-like intersections as never * Accept new baselines * Fix compiler issues revealed by increased intersection correctness * Delete fourslash tests that are no longer applicable * Include isNeverLikeIntersection check in getNormalizedType * Erase never-like types in several more places * Check that base types are not never-like * Add comments * Revert isNeverLikeType check in getIndexType (keyof shouldn't resolve member types) * Introduce getReducedType for union and intersection types * Don't reduce in getApparentType * Avoid relationship check in resolveMappedTypeMembers * Accept new baselines * Don't call getReducedType in getIndexType * Ensure reduced and unreduced forms of a type can compare identical * Reduce types before converting them to string representation * Accept new baselines * Reduce intersections before obtaining keyof X * Add tests * Accept new baselines * Fix comment in tests * Don't infer from empty intersection types * Add tests * Accept new baselines * Defer instantiation of mapped type property types * Accept new baselines * Include more precise type in diagnostic * Accept new baselines * Minor optimization * Improve error message * Optional properties in intersections are never discriminants
100 lines
2.7 KiB
TypeScript
100 lines
2.7 KiB
TypeScript
// @strict: true
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declare const sym1: unique symbol;
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declare const sym2: unique symbol;
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type T1 = string & 'a'; // 'a'
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type T2 = 'a' & string & 'b'; // never
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type T3 = number & 10; // 10
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type T4 = 10 & number & 20; // never
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type T5 = symbol & typeof sym1; // typeof sym1
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type T6 = typeof sym1 & symbol & typeof sym2; // never
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type T7 = string & 'a' & number & 10 & symbol & typeof sym1; // never
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type T10 = string & ('a' | 'b'); // 'a' | 'b'
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type T11 = (string | number) & ('a' | 10); // 'a' | 10
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type N1 = 'a' & 'b';
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type N2 = { a: string } & null;
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type N3 = { a: string } & undefined;
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type N4 = string & number;
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type N5 = number & object;
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type N6 = symbol & string;
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type N7 = void & string;
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type X = { x: string };
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type X1 = X | 'a' & 'b';
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type X2 = X | { a: string } & null;
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type X3 = X | { a: string } & undefined;
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type X4 = X | string & number;
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type X5 = X | number & object;
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type X6 = X | symbol & string;
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type X7 = X | void & string;
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type A = { kind: 'a', foo: string };
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type B = { kind: 'b', foo: number };
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type C = { kind: 'c', foo: number };
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declare let ab: A & B;
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ab.kind; // Error
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declare let x: A | (B & C); // A
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let a: A = x;
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type AB = A & B; // never
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type BC = B & C; // never
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type U1 = Partial<A & B>; // never
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type U2 = Readonly<A & B>; // never
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type U3 = (A & B)['kind']; // never
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type U4 = A & B | B & C; // never
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type U5 = A | B & C; // A
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type K1 = keyof (A & B); // string | number | symbol
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type K2 = keyof A | keyof B; // 'kind' | 'foo'
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type Merge1<T, U> = { [P in keyof (T & U)]: P extends keyof T ? T[P] : U[P & keyof U] }
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type Merge2<T, U> = { [P in keyof T | keyof U]: P extends keyof T ? T[P] : U[P & keyof U] }
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type M1 = { a: 1, b: 2 } & { a: 2, c: 3 }; // never
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type M2 = Merge1<{ a: 1, b: 2 }, { a: 2, c: 3 }>; // {}
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type M3 = Merge2<{ a: 1, b: 2 }, { a: 2, c: 3 }>; // { a: 1, b: 2, c: 3 }
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// Repro from #31663
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const x1 = { a: 'foo', b: 42 };
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const x2 = { a: 'foo', b: true };
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declare let k: 'a' | 'b';
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x1[k] = 'bar' as any; // Error
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x2[k] = 'bar' as any; // Error
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const enum Tag1 {}
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const enum Tag2 {}
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declare let s1: string & Tag1;
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declare let s2: string & Tag2;
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declare let t1: string & Tag1 | undefined;
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declare let t2: string & Tag2 | undefined;
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s1 = s2;
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s2 = s1;
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t1 = t2;
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t2 = t1;
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// Repro from #36736
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const f1 = (t: "a" | ("b" & "c")): "a" => t;
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type Container<Type extends string> = {
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type: Type;
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}
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const f2 = (t: Container<"a"> | (Container<"b"> & Container<"c">)): Container<"a"> => t;
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const f3 = (t: Container<"a"> | (Container<"b"> & { dataB: boolean } & Container<"a">)): Container<"a"> => t;
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const f4 = (t: number | (Container<"b"> & { dataB: boolean } & Container<"a">)): number => t;
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