25 lines
803 B
TypeScript
25 lines
803 B
TypeScript
// @strict: true
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// @declaration: true
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// Repro from #17456
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type StringContains<S extends string, L extends string> = ({ [K in S]: 'true' } & { [key: string]: 'false'})[L];
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type ObjectHasKey<O, L extends string> = StringContains<Extract<keyof O, string>, L>;
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type A<T> = ObjectHasKey<T, '0'>;
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type B = ObjectHasKey<[string, number], '1'>; // "true"
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type C = ObjectHasKey<[string, number], '2'>; // "false"
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type D = A<[string]>; // "true"
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// Error, "false" not handled
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type E<T> = { true: 'true' }[ObjectHasKey<T, '1'>];
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type Juxtapose<T> = ({ true: 'otherwise' } & { [k: string]: 'true' })[ObjectHasKey<T, '1'>];
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// Error, "otherwise" is missing
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type DeepError<T> = { true: 'true' }[Juxtapose<T>];
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type DeepOK<T> = { true: 'true', otherwise: 'false' }[Juxtapose<T>];
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