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
47 lines
3.2 KiB
Plaintext
47 lines
3.2 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 : (x: any) => x is number
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>x : any
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>x : any
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return typeof x === "number";
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>typeof x === "number" : boolean
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>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
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>x : any
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>"number" : "number"
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}
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const arrayOfStringsNumbersAndBooleans = ["string", false, 0, "strung", 1, true];
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>arrayOfStringsNumbersAndBooleans : (string | number | boolean)[]
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>["string", false, 0, "strung", 1, true] : (string | number | boolean)[]
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>"string" : "string"
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>false : false
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>0 : 0
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>"strung" : "strung"
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>1 : 1
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>true : true
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const foundNumber: number | undefined = arrayOfStringsNumbersAndBooleans.find(isNumber);
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>foundNumber : number
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>arrayOfStringsNumbersAndBooleans.find(isNumber) : number
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>arrayOfStringsNumbersAndBooleans.find : { <S extends string | number | boolean>(predicate: (this: void, value: string | number | boolean, index: number, obj: (string | number | boolean)[]) => value is S, thisArg?: any): S; (predicate: (value: string | number | boolean, index: number, obj: (string | number | boolean)[]) => boolean, thisArg?: any): string | number | boolean; }
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>arrayOfStringsNumbersAndBooleans : (string | number | boolean)[]
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>find : { <S extends string | number | boolean>(predicate: (this: void, value: string | number | boolean, index: number, obj: (string | number | boolean)[]) => value is S, thisArg?: any): S; (predicate: (value: string | number | boolean, index: number, obj: (string | number | boolean)[]) => boolean, thisArg?: any): string | number | boolean; }
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>isNumber : (x: any) => x is number
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const readonlyArrayOfStringsNumbersAndBooleans = arrayOfStringsNumbersAndBooleans as ReadonlyArray<string | number | boolean>;
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>readonlyArrayOfStringsNumbersAndBooleans : ReadonlyArray<string | number | boolean>
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>arrayOfStringsNumbersAndBooleans as ReadonlyArray<string | number | boolean> : ReadonlyArray<string | number | boolean>
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>arrayOfStringsNumbersAndBooleans : (string | number | boolean)[]
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>ReadonlyArray : ReadonlyArray<T>
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const readonlyFoundNumber: number | undefined = readonlyArrayOfStringsNumbersAndBooleans.find(isNumber);
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>readonlyFoundNumber : number
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>readonlyArrayOfStringsNumbersAndBooleans.find(isNumber) : number
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>readonlyArrayOfStringsNumbersAndBooleans.find : { <S extends string | number | boolean>(predicate: (this: void, value: string | number | boolean, index: number, obj: ReadonlyArray<string | number | boolean>) => value is S, thisArg?: any): S; (predicate: (value: string | number | boolean, index: number, obj: ReadonlyArray<string | number | boolean>) => boolean, thisArg?: any): string | number | boolean; }
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>readonlyArrayOfStringsNumbersAndBooleans : ReadonlyArray<string | number | boolean>
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>find : { <S extends string | number | boolean>(predicate: (this: void, value: string | number | boolean, index: number, obj: ReadonlyArray<string | number | boolean>) => value is S, thisArg?: any): S; (predicate: (value: string | number | boolean, index: number, obj: ReadonlyArray<string | number | boolean>) => boolean, thisArg?: any): string | number | boolean; }
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>isNumber : (x: any) => x is number
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