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Cherry-pick PR #50610 into release-4.8 (#50612)
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Component commits:
908548e 'in' operator shouldn't narrow {} originating in unknown

517777d Add regression test

Co-authored-by: Anders Hejlsberg <[email protected]>
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TypeScript Bot and ahejlsberg authored Sep 2, 2022
1 parent 10870b4 commit 4083b46
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Showing 5 changed files with 130 additions and 1 deletion.
2 changes: 1 addition & 1 deletion src/compiler/checker.ts
Original file line number Diff line number Diff line change
Expand Up @@ -25117,7 +25117,7 @@ namespace ts {

function narrowByInKeyword(type: Type, name: __String, assumeTrue: boolean) {
if (type.flags & TypeFlags.Union
|| type.flags & TypeFlags.Object && declaredType !== type
|| type.flags & TypeFlags.Object && declaredType !== type && !(declaredType === unknownType && isEmptyAnonymousObjectType(type))
|| isThisTypeParameter(type)
|| type.flags & TypeFlags.Intersection && every((type as IntersectionType).types, t => t.symbol !== globalThisSymbol)) {
return filterType(type, t => isTypePresencePossible(t, name, assumeTrue));
Expand Down
36 changes: 36 additions & 0 deletions tests/baselines/reference/inKeywordAndUnknown.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,36 @@
//// [inKeywordAndUnknown.ts]
// Repro from #50531

function f(x: {}, y: unknown) {
if (!("a" in x)) {
return;
}
x; // {}
if (!y) {
return;
}
y; // {}
if (!("a" in y)) {
return;
}
y; // {}
}


//// [inKeywordAndUnknown.js]
"use strict";
// Repro from #50531
function f(x, y) {
if (!("a" in x)) {
return;
}
x; // {}
if (!y) {
return;
}
y; // {}
if (!("a" in y)) {
return;
}
y; // {}
}
33 changes: 33 additions & 0 deletions tests/baselines/reference/inKeywordAndUnknown.symbols
Original file line number Diff line number Diff line change
@@ -0,0 +1,33 @@
=== tests/cases/compiler/inKeywordAndUnknown.ts ===
// Repro from #50531

function f(x: {}, y: unknown) {
>f : Symbol(f, Decl(inKeywordAndUnknown.ts, 0, 0))
>x : Symbol(x, Decl(inKeywordAndUnknown.ts, 2, 11))
>y : Symbol(y, Decl(inKeywordAndUnknown.ts, 2, 17))

if (!("a" in x)) {
>x : Symbol(x, Decl(inKeywordAndUnknown.ts, 2, 11))

return;
}
x; // {}
>x : Symbol(x, Decl(inKeywordAndUnknown.ts, 2, 11))

if (!y) {
>y : Symbol(y, Decl(inKeywordAndUnknown.ts, 2, 17))

return;
}
y; // {}
>y : Symbol(y, Decl(inKeywordAndUnknown.ts, 2, 17))

if (!("a" in y)) {
>y : Symbol(y, Decl(inKeywordAndUnknown.ts, 2, 17))

return;
}
y; // {}
>y : Symbol(y, Decl(inKeywordAndUnknown.ts, 2, 17))
}

42 changes: 42 additions & 0 deletions tests/baselines/reference/inKeywordAndUnknown.types
Original file line number Diff line number Diff line change
@@ -0,0 +1,42 @@
=== tests/cases/compiler/inKeywordAndUnknown.ts ===
// Repro from #50531

function f(x: {}, y: unknown) {
>f : (x: {}, y: unknown) => void
>x : {}
>y : unknown

if (!("a" in x)) {
>!("a" in x) : boolean
>("a" in x) : boolean
>"a" in x : boolean
>"a" : "a"
>x : {}

return;
}
x; // {}
>x : {}

if (!y) {
>!y : boolean
>y : unknown

return;
}
y; // {}
>y : {}

if (!("a" in y)) {
>!("a" in y) : boolean
>("a" in y) : boolean
>"a" in y : boolean
>"a" : "a"
>y : {}

return;
}
y; // {}
>y : {}
}

18 changes: 18 additions & 0 deletions tests/cases/compiler/inKeywordAndUnknown.ts
Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
// @strict: true

// Repro from #50531

function f(x: {}, y: unknown) {
if (!("a" in x)) {
return;
}
x; // {}
if (!y) {
return;
}
y; // {}
if (!("a" in y)) {
return;
}
y; // {}
}

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