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Make index signature declarations without a type annotation an implicit any, not a grammar error - #65283
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Andrew Branch (andrewbranch) merged 2 commits intoNov 3, 2026
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…it any, not a grammar error
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🟢 Approval recommended
The review identifies no active issues with the index-signature behavior and AST API changes.
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tsc/internal/diagnostics/diagnostics_generated.go: Generated file
What changed in this PR
This PR separates the index-signature behavior change from #65063: omitted value types become implicit any rather than grammar errors, with matching optionality in the TypeScript AST API.
Changes:
- Replace TS1021 with implicit-
anydiagnostic TS7062 whennoImplicitAnyis enabled. - Make index-signature types optional in the AST schema and generated factory APIs.
- Add compiler and API tests, including declaration emit, and update diagnostic baselines.
| File | Description |
|---|---|
tsc/testdata/tests/cases/compiler/indexSignatureMissingType.ts |
Tests omitted types with both noImplicitAny settings. |
tsc/testdata/baselines/reference/conformance/parserObjectType6.errors.txt |
Adds implicit-any diagnostic for an empty signature. |
tsc/testdata/baselines/reference/conformance/parserIndexSignature8.errors.txt |
Adds implicit-any diagnostics alongside invalid-key errors. |
tsc/testdata/baselines/reference/conformance/parserIndexSignature7.errors.txt |
Replaces the missing-type grammar diagnostic. |
tsc/testdata/baselines/reference/conformance/parserIndexSignature6.errors.txt |
Records implicit any alongside the boolean-key error. |
tsc/testdata/baselines/reference/conformance/parserIndexSignature11.errors.txt |
Removes the obsolete missing-type error. |
tsc/testdata/baselines/reference/compiler/indexWithoutParamType.errors.txt |
Records implicit any for an empty signature. |
tsc/testdata/baselines/reference/compiler/indexTypeCheck.errors.txt |
Removes errors for permitted omitted types. |
tsc/testdata/baselines/reference/compiler/indexSignatureWithoutTypeAnnotation1.errors.txt |
Updates the class index-signature diagnostic. |
tsc/testdata/baselines/reference/compiler/indexSignatureTypeCheck2.errors.txt |
Adds implicit-any diagnostics for malformed signatures. |
tsc/testdata/baselines/reference/compiler/indexSignatureTypeCheck.errors.txt |
Adds implicit-any diagnostics while retaining parameter errors. |
tsc/testdata/baselines/reference/compiler/indexSignatureMustHaveTypeAnnotation.errors.txt |
Replaces missing-type grammar errors with TS7062. |
tsc/testdata/baselines/reference/compiler/indexSignatureMissingType(noimplicitany=true).types |
Records inferred any types with checking enabled. |
tsc/testdata/baselines/reference/compiler/indexSignatureMissingType(noimplicitany=true).symbols |
Records symbol bindings with checking enabled. |
tsc/testdata/baselines/reference/compiler/indexSignatureMissingType(noimplicitany=true).js |
Records JavaScript and explicit-any declaration emit. |
tsc/testdata/baselines/reference/compiler/indexSignatureMissingType(noimplicitany=true).errors.txt |
Records implicit-any and existing validation errors. |
tsc/testdata/baselines/reference/compiler/indexSignatureMissingType(noimplicitany=false).types |
Records inferred any types with checking disabled. |
tsc/testdata/baselines/reference/compiler/indexSignatureMissingType(noimplicitany=false).symbols |
Records symbol bindings with checking disabled. |
tsc/testdata/baselines/reference/compiler/indexSignatureMissingType(noimplicitany=false).js |
Records JavaScript and declaration emit with checking disabled. |
tsc/testdata/baselines/reference/compiler/indexSignatureMissingType(noimplicitany=false).errors.txt |
Confirms only unrelated validation errors remain. |
tsc/testdata/baselines/reference/compiler/indexerConstraints2.errors.txt |
Updates the missing-type diagnostic. |
tsc/testdata/baselines/reference/compiler/giant.errors.txt |
Removes obsolete missing-type grammar errors. |
tsc/testdata/baselines/reference/compiler/arraySigChecking.errors.txt |
Adds implicit any alongside an invalid-key error. |
tsc/internal/diagnostics/diagnostics_generated.go |
Regenerates Go diagnostic definitions. |
tsc/internal/diagnostics/diagnosticMessages.json |
Replaces TS1021 with TS7062. |
tsc/internal/diagnostics/diagnosticMessages.generated.json |
Updates generated diagnostic messages. |
tsc/internal/checker/grammarchecks.go |
Removes the mandatory value-type grammar check. |
tsc/internal/checker/checker.go |
Reports implicit any for unannotated index signatures. |
tools/scripts/tsc/ast.json |
Marks index-signature types optional in the schema. |
packages/typescript/test/sync/ast.test.ts |
Tests parsed and factory-created signatures without types. |
packages/typescript/src/ast/factory.generated.ts |
Allows omitted types in create and update factories. |
packages/typescript/src/ast/ast.generated.ts |
Removes the required-type override. |
Review effort: Balanced
Merged
Andrew Branch (andrewbranch)
requested review from
Ryan Cavanaugh (RyanCavanaugh) and
Jake Bailey (jakebailey)
November 3, 2026 17:50
Jake Bailey (jakebailey)
approved these changes
Nov 3, 2026
Jake Bailey (jakebailey)
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Jake Bailey (jakebailey)
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LGTM but merge conflict
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Jake Bailey (jakebailey)
approved these changes
Nov 3, 2026
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Extracted out of #65063
was previously a grammar error; now it's an implicit
any.