Handle type guard predicates on Array<T>.find (#18160)

* 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
This commit is contained in:
Joe Calzaretta 2017-10-09 17:58:41 -04:00 committed by Mohamed Hegazy
parent 8b60736b61
commit bb3467b8e1
5 changed files with 115 additions and 0 deletions

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@ -10,6 +10,7 @@ interface Array<T> {
* @param thisArg If provided, it will be used as the this value for each invocation of
* predicate. If it is not provided, undefined is used instead.
*/
find<S extends T>(predicate: (this: void, value: T, index: number, obj: T[]) => value is S, thisArg?: any): S | undefined;
find(predicate: (value: T, index: number, obj: T[]) => boolean, thisArg?: any): T | undefined;
/**
@ -350,6 +351,7 @@ interface ReadonlyArray<T> {
* @param thisArg If provided, it will be used as the this value for each invocation of
* predicate. If it is not provided, undefined is used instead.
*/
find<S extends T>(predicate: (this: void, value: T, index: number, obj: ReadonlyArray<T>) => value is S, thisArg?: any): S | undefined;
find(predicate: (value: T, index: number, obj: ReadonlyArray<T>) => boolean, thisArg?: any): T | undefined;
/**

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@ -0,0 +1,22 @@
//// [arrayFind.ts]
// test fix for #18112, type guard predicates should narrow returned element
function isNumber(x: any): x is number {
return typeof x === "number";
}
const arrayOfStringsNumbersAndBooleans = ["string", false, 0, "strung", 1, true];
const foundNumber: number | undefined = arrayOfStringsNumbersAndBooleans.find(isNumber);
const readonlyArrayOfStringsNumbersAndBooleans = arrayOfStringsNumbersAndBooleans as ReadonlyArray<string | number | boolean>;
const readonlyFoundNumber: number | undefined = readonlyArrayOfStringsNumbersAndBooleans.find(isNumber);
//// [arrayFind.js]
// test fix for #18112, type guard predicates should narrow returned element
function isNumber(x) {
return typeof x === "number";
}
var arrayOfStringsNumbersAndBooleans = ["string", false, 0, "strung", 1, true];
var foundNumber = arrayOfStringsNumbersAndBooleans.find(isNumber);
var readonlyArrayOfStringsNumbersAndBooleans = arrayOfStringsNumbersAndBooleans;
var readonlyFoundNumber = readonlyArrayOfStringsNumbersAndBooleans.find(isNumber);

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@ -0,0 +1,33 @@
=== tests/cases/compiler/arrayFind.ts ===
// test fix for #18112, type guard predicates should narrow returned element
function isNumber(x: any): x is number {
>isNumber : Symbol(isNumber, Decl(arrayFind.ts, 0, 0))
>x : Symbol(x, Decl(arrayFind.ts, 1, 18))
>x : Symbol(x, Decl(arrayFind.ts, 1, 18))
return typeof x === "number";
>x : Symbol(x, Decl(arrayFind.ts, 1, 18))
}
const arrayOfStringsNumbersAndBooleans = ["string", false, 0, "strung", 1, true];
>arrayOfStringsNumbersAndBooleans : Symbol(arrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 5, 5))
const foundNumber: number | undefined = arrayOfStringsNumbersAndBooleans.find(isNumber);
>foundNumber : Symbol(foundNumber, Decl(arrayFind.ts, 6, 5))
>arrayOfStringsNumbersAndBooleans.find : Symbol(Array.find, Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
>arrayOfStringsNumbersAndBooleans : Symbol(arrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 5, 5))
>find : Symbol(Array.find, Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
>isNumber : Symbol(isNumber, Decl(arrayFind.ts, 0, 0))
const readonlyArrayOfStringsNumbersAndBooleans = arrayOfStringsNumbersAndBooleans as ReadonlyArray<string | number | boolean>;
>readonlyArrayOfStringsNumbersAndBooleans : Symbol(readonlyArrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 8, 5))
>arrayOfStringsNumbersAndBooleans : Symbol(arrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 5, 5))
>ReadonlyArray : Symbol(ReadonlyArray, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.iterable.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
const readonlyFoundNumber: number | undefined = readonlyArrayOfStringsNumbersAndBooleans.find(isNumber);
>readonlyFoundNumber : Symbol(readonlyFoundNumber, Decl(arrayFind.ts, 9, 5))
>readonlyArrayOfStringsNumbersAndBooleans.find : Symbol(ReadonlyArray.find, Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
>readonlyArrayOfStringsNumbersAndBooleans : Symbol(readonlyArrayOfStringsNumbersAndBooleans, Decl(arrayFind.ts, 8, 5))
>find : Symbol(ReadonlyArray.find, Decl(lib.es2015.core.d.ts, --, --), Decl(lib.es2015.core.d.ts, --, --))
>isNumber : Symbol(isNumber, Decl(arrayFind.ts, 0, 0))

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@ -0,0 +1,46 @@
=== tests/cases/compiler/arrayFind.ts ===
// test fix for #18112, type guard predicates should narrow returned element
function isNumber(x: any): x is number {
>isNumber : (x: any) => x is number
>x : any
>x : any
return typeof x === "number";
>typeof x === "number" : boolean
>typeof x : "string" | "number" | "boolean" | "symbol" | "undefined" | "object" | "function"
>x : any
>"number" : "number"
}
const arrayOfStringsNumbersAndBooleans = ["string", false, 0, "strung", 1, true];
>arrayOfStringsNumbersAndBooleans : (string | number | boolean)[]
>["string", false, 0, "strung", 1, true] : (string | number | boolean)[]
>"string" : "string"
>false : false
>0 : 0
>"strung" : "strung"
>1 : 1
>true : true
const foundNumber: number | undefined = arrayOfStringsNumbersAndBooleans.find(isNumber);
>foundNumber : number
>arrayOfStringsNumbersAndBooleans.find(isNumber) : number
>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; }
>arrayOfStringsNumbersAndBooleans : (string | number | boolean)[]
>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; }
>isNumber : (x: any) => x is number
const readonlyArrayOfStringsNumbersAndBooleans = arrayOfStringsNumbersAndBooleans as ReadonlyArray<string | number | boolean>;
>readonlyArrayOfStringsNumbersAndBooleans : ReadonlyArray<string | number | boolean>
>arrayOfStringsNumbersAndBooleans as ReadonlyArray<string | number | boolean> : ReadonlyArray<string | number | boolean>
>arrayOfStringsNumbersAndBooleans : (string | number | boolean)[]
>ReadonlyArray : ReadonlyArray<T>
const readonlyFoundNumber: number | undefined = readonlyArrayOfStringsNumbersAndBooleans.find(isNumber);
>readonlyFoundNumber : number
>readonlyArrayOfStringsNumbersAndBooleans.find(isNumber) : number
>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; }
>readonlyArrayOfStringsNumbersAndBooleans : ReadonlyArray<string | number | boolean>
>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; }
>isNumber : (x: any) => x is number

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@ -0,0 +1,12 @@
// @lib: es2015
// test fix for #18112, type guard predicates should narrow returned element
function isNumber(x: any): x is number {
return typeof x === "number";
}
const arrayOfStringsNumbersAndBooleans = ["string", false, 0, "strung", 1, true];
const foundNumber: number | undefined = arrayOfStringsNumbersAndBooleans.find(isNumber);
const readonlyArrayOfStringsNumbersAndBooleans = arrayOfStringsNumbersAndBooleans as ReadonlyArray<string | number | boolean>;
const readonlyFoundNumber: number | undefined = readonlyArrayOfStringsNumbersAndBooleans.find(isNumber);