bb3467b8e1
* Handle type guard predicates on `Array<T>.find` If the `predicate` function passed to `Array<T>.find` or `ReadonlyArray<T>.find` is a type guard narrowing `value` to type `S`, then any returned element should also be narrowed to `S`. Adding test case and associated baselines * trailing whitespace after merge conflict
34 lines
2.2 KiB
Plaintext
34 lines
2.2 KiB
Plaintext
=== tests/cases/compiler/arrayFind.ts ===
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// test fix for #18112, type guard predicates should narrow returned element
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function isNumber(x: any): x is number {
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>isNumber : Symbol(isNumber, Decl(arrayFind.ts, 0, 0))
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>x : Symbol(x, Decl(arrayFind.ts, 1, 18))
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>x : Symbol(x, Decl(arrayFind.ts, 1, 18))
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return typeof x === "number";
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>x : Symbol(x, Decl(arrayFind.ts, 1, 18))
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}
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const arrayOfStringsNumbersAndBooleans = ["string", false, 0, "strung", 1, true];
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>arrayOfStringsNumbersAndBooleans : Symbol(arrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 5, 5))
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const foundNumber: number | undefined = arrayOfStringsNumbersAndBooleans.find(isNumber);
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>foundNumber : Symbol(foundNumber, Decl(arrayFind.ts, 6, 5))
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>arrayOfStringsNumbersAndBooleans.find : Symbol(Array.find, Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
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>arrayOfStringsNumbersAndBooleans : Symbol(arrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 5, 5))
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>find : Symbol(Array.find, Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
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>isNumber : Symbol(isNumber, Decl(arrayFind.ts, 0, 0))
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const readonlyArrayOfStringsNumbersAndBooleans = arrayOfStringsNumbersAndBooleans as ReadonlyArray<string | number | boolean>;
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>readonlyArrayOfStringsNumbersAndBooleans : Symbol(readonlyArrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 8, 5))
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>arrayOfStringsNumbersAndBooleans : Symbol(arrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 5, 5))
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>ReadonlyArray : Symbol(ReadonlyArray, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
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const readonlyFoundNumber: number | undefined = readonlyArrayOfStringsNumbersAndBooleans.find(isNumber);
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>readonlyFoundNumber : Symbol(readonlyFoundNumber, Decl(arrayFind.ts, 9, 5))
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>readonlyArrayOfStringsNumbersAndBooleans.find : Symbol(ReadonlyArray.find, Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
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>readonlyArrayOfStringsNumbersAndBooleans : Symbol(readonlyArrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 8, 5))
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>find : Symbol(ReadonlyArray.find, Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
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>isNumber : Symbol(isNumber, Decl(arrayFind.ts, 0, 0))
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