Fix transform crash with destructured parameter property #63043
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typescript-bot added Author: Team For Uncommitted Bug Contributor
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Pull request overview
This PR fixes a crash in the TypeScript transformer when processing destructured parameter properties with ES2024 target. The code in question is illegal TypeScript (parameter properties cannot use binding patterns), but the compiler should not crash when processing it - it should emit the appropriate error and continue.
Changes:
- Added a runtime check to skip parameter properties with non-identifier names (destructuring patterns) during class member transformation
- Added a test case to ensure the fix works with ES2024 target
Reviewed changes
Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.
Show a summary per file
| File | Description |
|---|---|
src/compiler/transformers/ts.ts | Added defensive check to skip destructured parameter properties before attempting to create property declarations |
tests/cases/compiler/declarationEmitDestructuringParameterProperties2.ts | Test case demonstrating the issue with ES2024 target |
tests/baselines/reference/declarationEmitDestructuringParameterProperties2.types | Baseline showing type inference for the test case |
tests/baselines/reference/declarationEmitDestructuringParameterProperties2.symbols | Baseline showing symbol resolution for the test case |
tests/baselines/reference/declarationEmitDestructuringParameterProperties2.js | Baseline showing JS output with ES2024 target (modern class syntax) |
tests/baselines/reference/declarationEmitDestructuringParameterProperties2.errors.txt | Baseline showing expected TS1187 errors for illegal destructured parameter properties |
DanielRosenwasser approved these changes Jan 23, 2026
jakebailey changed the title Merged via the queue into microsoft:main with commit Jan 23, 2026
b19a9da 38 of 39 checks passed
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Found this while working on moving the target up to ES2024. This is illegal code, but we need to not attempt to transform it otherwise it'll break later.