Skip to content

Tuple union types incorrectly infer never type #22562

Closed
@falsandtru

Description

@falsandtru

separated from #22432

TypeScript Version: 2.7.0-dev.20180307

Search Terms:

Code

type C<R> = [R[]] | [R[], void];
declare function h<T>(f: C<T>): void;
h([[]] as [never[]]); // T: never[]
h([[]] as [void[]]); // T: void

Expected behavior:

h([[]] as [never[]]); // T: never
h([[]] as [void[]]); // T: void

Actual behavior:

h([[]] as [never[]]); // T: never[]
h([[]] as [void[]]); // T: void

Playground Link:

Related Issues:

Metadata

Metadata

Assignees

Labels

BugA bug in TypeScriptFixedA PR has been merged for this issue

Type

No type

Projects

No projects

Relationships

None yet

Development

No branches or pull requests

Issue actions