Skip to content

Support custom 'Symbol.hasInstance' methods when narrowing 'instanceof' #55052

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
rbuckton merged 15 commits into from
Sep 29, 2023
Merged

Support custom 'Symbol.hasInstance' methods when narrowing 'instanceof' #55052

Show file tree
Hide file tree
Changes from 1 commit
Commits
Show all changes
15 commits
Select commit Hold shift + click to select a range
69f59da
[WIP] Support custom 'Symbol.hasInstance' methods when checking/narro…
rbuckton Jul 17, 2023
161d1f1
Add tests for instanceof and narrowing
rbuckton Jul 17, 2023
6a4f838
Accept baseline, fix lint
rbuckton Jul 17, 2023
af6bb55
Check derived types when using type predicates with instanceof/hasIns…
rbuckton Aug 12, 2023
6a83254
Small tweaks, lint fixes, and baseline updates
rbuckton Aug 14, 2023
511c955
Add go-to-definition support on 'instanceof' keyword
rbuckton Sep 18, 2023
9e3adb4
Merge branch 'main' into instanceof-Symbol.hasInstance
rbuckton Sep 18, 2023
4b0eafc
Fix format
rbuckton Sep 19, 2023
befa293
Address PR feedback
rbuckton Sep 19, 2023
559047e
Comment cleanup
rbuckton Sep 22, 2023
8af777e
Switch synthetic call to use use 'resolveSignature' flow
rbuckton Sep 26, 2023
f3e94f0
Merge branch 'main' into instanceof-Symbol.hasInstance
rbuckton Sep 26, 2023
1d90af1
Run formatting
rbuckton Sep 26, 2023
b65f9bc
Merge branch 'main' into instanceof-Symbol.hasInstance
rbuckton Sep 27, 2023
0554f56
Remove branch for 'instanceof' error message reporting
rbuckton Sep 29, 2023
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
Prev Previous commit
Next Next commit
Accept baseline, fix lint
  • Loading branch information
@rbuckton
rbuckton committed Jul 17, 2023
commit 6a4f838e705bf0cffde30e62bf93f570f8398353
4 changes: 2 additions & 2 deletions src/compiler/checker.ts
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -36541,7 +36541,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
const hasInstanceMethodType = getSymbolHasInstanceMethodOfObjectType(rightType);
if (hasInstanceMethodType) {
// avoid a complex check for every `instanceof` when the `[Symbol.hasInstance]` method has a single
// call signature that neither restricts nor narrows (via type predicate) the LHS value, e.g.
// call signature that neither restricts nor narrows (via type predicate) the LHS value, e.g.
// `(value: unknown) => boolean`.
const cache = hasInstanceMethodType as HasInstanceMethodType;
if (cache.hasSimpleUnrestrictedSingleCallSignature === undefined) {
Expand All @@ -36558,7 +36558,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
// parameter.
const syntheticCall = createSyntheticHasInstanceMethodCall(left, right, leftType, hasInstanceMethodType);
const returnType = getReturnTypeOfSignature(getResolvedSignature(syntheticCall));

// We also verify that the return type of the `[Symbol.hasInstance]` method is assignable to
// `boolean`. According to the spec, the runtime will actually perform `ToBoolean` on the result,
// but this is more type-safe.
Expand Down
8 changes: 4 additions & 4 deletions tests/baselines/reference/symbolType1.errors.txt
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
symbolType1.ts(1,1): error TS2358: The left-hand side of an 'instanceof' expression must be of type 'any', an object type or a type parameter.
symbolType1.ts(2,19): error TS2359: The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type.
symbolType1.ts(4,19): error TS2359: The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type.
symbolType1.ts(2,19): error TS2857: The right-hand side of an 'instanceof' expression must be either of type 'any', an object type with a '[Symbol.hasInstance]()' method, or a type assignable to the 'Function' interface type.
symbolType1.ts(4,19): error TS2857: The right-hand side of an 'instanceof' expression must be either of type 'any', an object type with a '[Symbol.hasInstance]()' method, or a type assignable to the 'Function' interface type.


==== symbolType1.ts (3 errors) ====
Expand All @@ -9,8 +9,8 @@ symbolType1.ts(4,19): error TS2359: The right-hand side of an 'instanceof' expre
!!! error TS2358: The left-hand side of an 'instanceof' expression must be of type 'any', an object type or a type parameter.
Symbol instanceof Symbol();
~~~~~~~~
!!! error TS2359: The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type.
!!! error TS2857: The right-hand side of an 'instanceof' expression must be either of type 'any', an object type with a '[Symbol.hasInstance]()' method, or a type assignable to the 'Function' interface type.
(Symbol() || {}) instanceof Object; // This one should be okay, it's a valid way of distinguishing types
Symbol instanceof (Symbol() || {});
~~~~~~~~~~~~~~~~
!!! error TS2359: The right-hand side of an 'instanceof' expression must be of type 'any' or of a type assignable to the 'Function' interface type.
!!! error TS2857: The right-hand side of an 'instanceof' expression must be either of type 'any', an object type with a '[Symbol.hasInstance]()' method, or a type assignable to the 'Function' interface type.