microsoft / microsoft/TypeScript
Middle operand in comma operator list not properly checked for side-effect-freeness
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Bug
Domain: Error Messages
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Description
TypeScript Version: master at f304b81fa54285f
Search Terms: comma side effects
Code
declare const obj: any;
console.log(`${JSON.stringify(obj), undefined, 2}`);
Expected behavior: error TS2695: Left side of comma operator is unused and has no side effects.
Actual behavior: No errors
Related Issues:
#10814
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
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- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Reproduce the TypeScript version of the issue with the provided comma-expression example, then trace the compiler's side-effect checking for the middle operand. Compare the behavior with related issue #10814. Done means the example reports TS2695 for the unused, side-effect-free operand without introducing errors for valid comma expressions.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 48/100