microsoft / microsoft/TypeScript
Improve errors for potential arrow functions
Open
Nobody has claimed this yet.
Bug
Domain: Error Messages
Effort: Moderate
Help Wanted
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- Go
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Description
There are certain locations where arrow functions don't parse
var x = window.foo || () => {}
In these instances, it would be nice if users could get a better error message as to avoid issues like #25897.
Ideally this should not be an invasive change.
- The change should be limited in scope.
- The parser should continue erroring in those locations.
- The change must not introduce change how existing valid code is parsed.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the parser handling for the invalid arrow-function form shown in the issue and reproduce the diagnostic for var x = window.foo || () => {}. Done means the parser still rejects these locations, reports a more useful error, and does not change parsing of existing valid code.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- typescript
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100