Fixes #16509 by making the change from #15938 less strict. This is technically a hole, but it's not as big a hole as before #15938.
45 lines
1.8 KiB
TypeScript
45 lines
1.8 KiB
TypeScript
// @strictNullChecks: true
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function f(
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definiteBoolean: { sn: boolean },
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definiteString: { sn: string },
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optionalString: { sn?: string },
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optionalNumber: { sn?: number },
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undefinedString: { sn: string | undefined },
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undefinedNumber: { sn: number | undefined }) {
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// optional
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let optionalUnionStops: { sn: string | number } = { ...definiteBoolean, ...definiteString, ...optionalNumber };
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let optionalUnionDuplicates: { sn: string | number } = { ...definiteBoolean, ...definiteString, ...optionalString, ...optionalNumber };
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let allOptional: { sn?: string | number } = { ...optionalString, ...optionalNumber };
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// undefined
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let undefinedUnionStops: { sn: string | number } = { ...definiteBoolean, ...definiteString, ...undefinedNumber };
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let undefinedUnionDuplicates: { sn: string | number } = { ...definiteBoolean, ...definiteString, ...undefinedString, ...undefinedNumber };
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let allUndefined: { sn: string | number | undefined } = { ...undefinedString, ...undefinedNumber };
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let undefinedWithOptionalContinues: { sn: string | number | boolean } = { ...definiteBoolean, ...undefinedString, ...optionalNumber };
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}
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type Movie = {
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title: string;
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yearReleased: number;
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}
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const m = { title: "The Matrix", yearReleased: 1999 };
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// should error here because title: undefined is not assignable to string
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const x: Movie = { ...m, title: undefined };
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interface Fields {
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foo: number;
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bar: string;
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}
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interface NearlyPartialFields {
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foo: number | undefined;
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bar: string | undefined;
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}
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function g(fields: Fields, partialFields: Partial<Fields>, nearlyPartialFields: NearlyPartialFields) {
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// ok, undefined is stripped from optional properties when spread
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fields = { ...fields, ...partialFields };
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// error: not optional, undefined remains
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fields = { ...fields, ...nearlyPartialFields };
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}
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