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Add regression test
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ahejlsberg committed Feb 17, 2021
1 parent 6b487a6 commit e7b6601
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Showing 4 changed files with 106 additions and 0 deletions.
23 changes: 23 additions & 0 deletions tests/baselines/reference/voidUndefinedReduction.js
@@ -0,0 +1,23 @@
//// [voidUndefinedReduction.ts]
// Repro from #42786

function isDefined<T>(value: T | undefined | null | void): value is T {
return value !== undefined && value !== null;
}

declare const foo: string | undefined;

if (isDefined(foo)) {
console.log(foo.toUpperCase());
}


//// [voidUndefinedReduction.js]
"use strict";
// Repro from #42786
function isDefined(value) {
return value !== undefined && value !== null;
}
if (isDefined(foo)) {
console.log(foo.toUpperCase());
}
33 changes: 33 additions & 0 deletions tests/baselines/reference/voidUndefinedReduction.symbols
@@ -0,0 +1,33 @@
=== tests/cases/compiler/voidUndefinedReduction.ts ===
// Repro from #42786

function isDefined<T>(value: T | undefined | null | void): value is T {
>isDefined : Symbol(isDefined, Decl(voidUndefinedReduction.ts, 0, 0))
>T : Symbol(T, Decl(voidUndefinedReduction.ts, 2, 19))
>value : Symbol(value, Decl(voidUndefinedReduction.ts, 2, 22))
>T : Symbol(T, Decl(voidUndefinedReduction.ts, 2, 19))
>value : Symbol(value, Decl(voidUndefinedReduction.ts, 2, 22))
>T : Symbol(T, Decl(voidUndefinedReduction.ts, 2, 19))

return value !== undefined && value !== null;
>value : Symbol(value, Decl(voidUndefinedReduction.ts, 2, 22))
>undefined : Symbol(undefined)
>value : Symbol(value, Decl(voidUndefinedReduction.ts, 2, 22))
}

declare const foo: string | undefined;
>foo : Symbol(foo, Decl(voidUndefinedReduction.ts, 6, 13))

if (isDefined(foo)) {
>isDefined : Symbol(isDefined, Decl(voidUndefinedReduction.ts, 0, 0))
>foo : Symbol(foo, Decl(voidUndefinedReduction.ts, 6, 13))

console.log(foo.toUpperCase());
>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
>foo.toUpperCase : Symbol(String.toUpperCase, Decl(lib.es5.d.ts, --, --))
>foo : Symbol(foo, Decl(voidUndefinedReduction.ts, 6, 13))
>toUpperCase : Symbol(String.toUpperCase, Decl(lib.es5.d.ts, --, --))
}

37 changes: 37 additions & 0 deletions tests/baselines/reference/voidUndefinedReduction.types
@@ -0,0 +1,37 @@
=== tests/cases/compiler/voidUndefinedReduction.ts ===
// Repro from #42786

function isDefined<T>(value: T | undefined | null | void): value is T {
>isDefined : <T>(value: T | undefined | null | void) => value is T
>value : void | T | null | undefined
>null : null

return value !== undefined && value !== null;
>value !== undefined && value !== null : boolean
>value !== undefined : boolean
>value : void | T | null | undefined
>undefined : undefined
>value !== null : boolean
>value : T | null
>null : null
}

declare const foo: string | undefined;
>foo : string | undefined

if (isDefined(foo)) {
>isDefined(foo) : boolean
>isDefined : <T>(value: void | T | null | undefined) => value is T
>foo : string | undefined

console.log(foo.toUpperCase());
>console.log(foo.toUpperCase()) : void
>console.log : (...data: any[]) => void
>console : Console
>log : (...data: any[]) => void
>foo.toUpperCase() : string
>foo.toUpperCase : () => string
>foo : string
>toUpperCase : () => string
}

13 changes: 13 additions & 0 deletions tests/cases/compiler/voidUndefinedReduction.ts
@@ -0,0 +1,13 @@
// @strict: true

// Repro from #42786

function isDefined<T>(value: T | undefined | null | void): value is T {
return value !== undefined && value !== null;
}

declare const foo: string | undefined;

if (isDefined(foo)) {
console.log(foo.toUpperCase());
}

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