Skip to content

fix(50340): typeof ... === "undefined" check on discriminated union of undefined and object type doesn't narrow correctly #50344

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Aug 31, 2022
Merged

fix(50340): typeof ... === "undefined" check on discriminated union of undefined and object type doesn't narrow correctly #50344

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
b4e02ab
fix(50340): narrow type by discriminant in typeof
a-tarasyuk Aug 17, 2022
5ffac1f
add additional test cases
a-tarasyuk Aug 27, 2022
c75043e
Merge branch 'main' of https://github.com/microsoft/TypeScript into f…
a-tarasyuk Aug 27, 2022
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 8 additions & 0 deletions src/compiler/checker.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -25328,11 +25328,19 @@ namespace ts {
}
const target = getReferenceCandidate(typeOfExpr.expression);
if (!isMatchingReference(reference, target)) {
const propertyAccess = getDiscriminantPropertyAccess(typeOfExpr.expression, type);
if (propertyAccess) {
return narrowTypeByDiscriminant(type, propertyAccess, t => narrowTypeByLiteralExpression(t, literal, assumeTrue));
}
if (strictNullChecks && optionalChainContainsReference(target, reference) && assumeTrue === (literal.text !== "undefined")) {
return getAdjustedTypeWithFacts(type, TypeFacts.NEUndefinedOrNull);
}
return type;
}
return narrowTypeByLiteralExpression(type, literal, assumeTrue);
}

function narrowTypeByLiteralExpression(type: Type, literal: LiteralExpression, assumeTrue: boolean) {
return assumeTrue ?
narrowTypeByTypeName(type, literal.text) :
getTypeWithFacts(type, typeofNEFacts.get(literal.text) || TypeFacts.TypeofNEHostObject);
Expand Down
31 changes: 31 additions & 0 deletions tests/baselines/reference/narrowingTypeofUndefined.js
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,31 @@
//// [narrowingTypeofUndefined.ts]
declare const a: { error: { prop: string }, result: undefined } | { error: undefined, result: { prop: number } }

if (typeof a.error === 'undefined') {
a.result.prop; // number
}
else {
a.error.prop; // string
}

if (typeof a.error !== 'undefined') {
a.error.prop; // string
}
else {
a.result.prop; // number
}


//// [narrowingTypeofUndefined.js]
if (typeof a.error === 'undefined') {
a.result.prop; // number
}
else {
a.error.prop; // string
}
if (typeof a.error !== 'undefined') {
a.error.prop; // string
}
else {
a.result.prop; // number
}
52 changes: 52 additions & 0 deletions tests/baselines/reference/narrowingTypeofUndefined.symbols
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,52 @@
=== tests/cases/compiler/narrowingTypeofUndefined.ts ===
declare const a: { error: { prop: string }, result: undefined } | { error: undefined, result: { prop: number } }
>a : Symbol(a, Decl(narrowingTypeofUndefined.ts, 0, 13))
>error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18))
>prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 27))
>result : Symbol(result, Decl(narrowingTypeofUndefined.ts, 0, 43))
>error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 67))
>result : Symbol(result, Decl(narrowingTypeofUndefined.ts, 0, 85))
>prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 95))

if (typeof a.error === 'undefined') {
>a.error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18), Decl(narrowingTypeofUndefined.ts, 0, 67))
>a : Symbol(a, Decl(narrowingTypeofUndefined.ts, 0, 13))
>error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18), Decl(narrowingTypeofUndefined.ts, 0, 67))

a.result.prop; // number
>a.result.prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 95))
>a.result : Symbol(result, Decl(narrowingTypeofUndefined.ts, 0, 43), Decl(narrowingTypeofUndefined.ts, 0, 85))
>a : Symbol(a, Decl(narrowingTypeofUndefined.ts, 0, 13))
>result : Symbol(result, Decl(narrowingTypeofUndefined.ts, 0, 43), Decl(narrowingTypeofUndefined.ts, 0, 85))
>prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 95))
}
else {
a.error.prop; // string
>a.error.prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 27))
>a.error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18), Decl(narrowingTypeofUndefined.ts, 0, 67))
>a : Symbol(a, Decl(narrowingTypeofUndefined.ts, 0, 13))
>error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18), Decl(narrowingTypeofUndefined.ts, 0, 67))
>prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 27))
}

if (typeof a.error !== 'undefined') {
>a.error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18), Decl(narrowingTypeofUndefined.ts, 0, 67))
>a : Symbol(a, Decl(narrowingTypeofUndefined.ts, 0, 13))
>error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18), Decl(narrowingTypeofUndefined.ts, 0, 67))

a.error.prop; // string
>a.error.prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 27))
>a.error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18), Decl(narrowingTypeofUndefined.ts, 0, 67))
>a : Symbol(a, Decl(narrowingTypeofUndefined.ts, 0, 13))
>error : Symbol(error, Decl(narrowingTypeofUndefined.ts, 0, 18), Decl(narrowingTypeofUndefined.ts, 0, 67))
>prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 27))
}
else {
a.result.prop; // number
>a.result.prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 95))
>a.result : Symbol(result, Decl(narrowingTypeofUndefined.ts, 0, 43), Decl(narrowingTypeofUndefined.ts, 0, 85))
>a : Symbol(a, Decl(narrowingTypeofUndefined.ts, 0, 13))
>result : Symbol(result, Decl(narrowingTypeofUndefined.ts, 0, 43), Decl(narrowingTypeofUndefined.ts, 0, 85))
>prop : Symbol(prop, Decl(narrowingTypeofUndefined.ts, 0, 95))
}

58 changes: 58 additions & 0 deletions tests/baselines/reference/narrowingTypeofUndefined.types
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,58 @@
=== tests/cases/compiler/narrowingTypeofUndefined.ts ===
declare const a: { error: { prop: string }, result: undefined } | { error: undefined, result: { prop: number } }
>a : { error: { prop: string;}; result: undefined; } | { error: undefined; result: { prop: number;}; }
>error : { prop: string; }
>prop : string
>result : undefined
>error : undefined
>result : { prop: number; }
>prop : number

if (typeof a.error === 'undefined') {
>typeof a.error === 'undefined' : boolean
>typeof a.error : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
>a.error : { prop: string; }
>a : { error: { prop: string; }; result: undefined; } | { error: undefined; result: { prop: number; }; }
>error : { prop: string; }
>'undefined' : "undefined"

a.result.prop; // number
>a.result.prop : number
>a.result : { prop: number; }
>a : { error: { prop: string; }; result: undefined; } | { error: undefined; result: { prop: number; }; }
>result : { prop: number; }
>prop : number
}
else {
a.error.prop; // string
>a.error.prop : string
>a.error : { prop: string; }
>a : { error: { prop: string; }; result: undefined; } | { error: undefined; result: { prop: number; }; }
>error : { prop: string; }
>prop : string
}

if (typeof a.error !== 'undefined') {
>typeof a.error !== 'undefined' : boolean
>typeof a.error : "string" | "number" | "bigint" | "boolean" | "symbol" | "undefined" | "object" | "function"
>a.error : { prop: string; }
>a : { error: { prop: string; }; result: undefined; } | { error: undefined; result: { prop: number; }; }
>error : { prop: string; }
>'undefined' : "undefined"

a.error.prop; // string
>a.error.prop : string
>a.error : { prop: string; }
>a : { error: { prop: string; }; result: undefined; } | { error: undefined; result: { prop: number; }; }
>error : { prop: string; }
>prop : string
}
else {
a.result.prop; // number
>a.result.prop : number
>a.result : { prop: number; }
>a : { error: { prop: string; }; result: undefined; } | { error: undefined; result: { prop: number; }; }
>result : { prop: number; }
>prop : number
}

15 changes: 15 additions & 0 deletions tests/cases/compiler/narrowingTypeofUndefined.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
declare const a: { error: { prop: string }, result: undefined } | { error: undefined, result: { prop: number } }

if (typeof a.error === 'undefined') {
a.result.prop; // number
}
else {
a.error.prop; // string
}

if (typeof a.error !== 'undefined') {
a.error.prop; // string
}
else {
a.result.prop; // number
}