19 lines
695 B
TypeScript
19 lines
695 B
TypeScript
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// @strict: true
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// repro from https://github.com/Microsoft/TypeScript/issues/25675
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// The type of `arg` blocks inference but simplifies to T.
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function logLength<T extends string, U extends string>(arg: { [K in U]: T }[U]): T {
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console.log(arg.length);
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return arg;
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}
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logLength(42); // error
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let z;
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z = logLength(42); // no error; T is inferred as `any`
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function logFirstLength<T extends string[], U extends string>(arg: { [K in U]: T }[U]): T {
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console.log(arg[0].length);
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return arg;
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}
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logFirstLength([42]); // error
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let zz = [];
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zz.push(logLength(42)); // no error; T is inferred as `any`
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zz = logFirstLength([42]); // no error; T is inferred as `any[]`
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