Skip to content

Port #62275: Discard types that reduce to never before discriminating by discriminable items #2749

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
jakebailey merged 2 commits into from
Feb 12, 2026
Merged

Port #62275: Discard types that reduce to never before discriminating by discriminable items #2749

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
95605b2
Initial plan
Copilot Feb 11, 2026
4bda7e9
Port TypeScript PR #62275: Discard types that reduce to never before …
Copilot Feb 11, 2026
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
2 changes: 1 addition & 1 deletion internal/checker/relater.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1205,7 +1205,7 @@ func (c *Checker) discriminateTypeByDiscriminableItems(target *Type, discriminat
types := target.Types()
include := make([]Ternary, len(types))
for i, t := range types {
if t.flags&TypeFlagsPrimitive == 0 {
if t.flags&TypeFlagsPrimitive == 0 && c.getReducedType(t).flags&TypeFlagsNever == 0 {
include[i] = TernaryTrue
}
}
Expand Down
55 changes: 0 additions & 55 deletions .../baselines/reference/submodule/compiler/contextuallyTypedByDiscriminableUnion2.errors.txt
View file
Open in desktop

This file was deleted.

59 changes: 0 additions & 59 deletions ...lines/reference/submodule/compiler/contextuallyTypedByDiscriminableUnion2.errors.txt.diff
View file
Open in desktop

This file was deleted.

8 changes: 4 additions & 4 deletions testdata/baselines/reference/submodule/compiler/contextuallyTypedByDiscriminableUnion2.types
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,7 @@ declare const item: string | null;
MyComponent({
>MyComponent({ enableD: true, value: item, setItem: (item) => {},}) : void
>MyComponent : <I extends Identifiable>(props: (DisableA & DisableB & DisableD<I>) | (DisableA & DisableB & EnableD<I>) | (DisableA & EnableB & DisableD<I>) | (DisableA & EnableB & EnableD<I>) | (EnableA & EnableB & DisableD<I>) | (EnableA & EnableB & EnableD<I>)) => void
>{ enableD: true, value: item, setItem: (item) => {},} : { enableD: true; value: string | null; setItem: (item: any) => void; }
>{ enableD: true, value: item, setItem: (item) => {},} : { enableD: true; value: string | null; setItem: (item: Identifiable | null) => void; }

enableD: true,
>enableD : true
Expand All @@ -91,9 +91,9 @@ MyComponent({
>item : string | null

setItem: (item) => {},
>setItem : (item: any) => void
>(item) => {} : (item: any) => void
>item : any
>setItem : (item: Identifiable | null) => void
>(item) => {} : (item: Identifiable | null) => void
>item : Identifiable | null

});

18 changes: 2 additions & 16 deletions .../baselines/reference/submodule/compiler/contextuallyTypedByDiscriminableUnion2.types.diff
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -16,21 +16,7 @@
MyComponent({
>MyComponent({ enableD: true, value: item, setItem: (item) => {},}) : void
->MyComponent : <I extends Identifiable>(props: MyComponentProps<I>) => void
->{ enableD: true, value: item, setItem: (item) => {},} : { enableD: true; value: string | null; setItem: (item: Identifiable | null) => void; }
+>MyComponent : <I extends Identifiable>(props: (DisableA & DisableB & DisableD<I>) | (DisableA & DisableB & EnableD<I>) | (DisableA & EnableB & DisableD<I>) | (DisableA & EnableB & EnableD<I>) | (EnableA & EnableB & DisableD<I>) | (EnableA & EnableB & EnableD<I>)) => void
+>{ enableD: true, value: item, setItem: (item) => {},} : { enableD: true; value: string | null; setItem: (item: any) => void; }
>{ enableD: true, value: item, setItem: (item) => {},} : { enableD: true; value: string | null; setItem: (item: Identifiable | null) => void; }

enableD: true,
>enableD : true
@@= skipped -12, +12 lines =@@
>item : string | null

setItem: (item) => {},
->setItem : (item: Identifiable | null) => void
->(item) => {} : (item: Identifiable | null) => void
->item : Identifiable | null
+>setItem : (item: any) => void
+>(item) => {} : (item: any) => void
+>item : any

});
enableD: true,
Loading