microsoft / microsoft/TypeScript

parameter property's modifier may not be followed by newline

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#28,396 1 comment 0 reactions 0 assignees View on GitHub

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Bug Domain: Parser
Dominant language
Go
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Merged PRs (30d)
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Description

TypeScript Version: has been that way since at least 2.4

Search Terms:

Code

class Foo {
  constructor(public
    foo: string) {}
}

Expected behavior:

Treat is as a parameter property. Or at least document this in the spec (related #28395)

Actual behavior:

Treats it as two parameters with a syntax error because of a missing comma.

Playground Link: https://agentcooper.github.io/typescript-play/#code/MYGwhgzhAEBiD29oG8BQ1rHgOwgFwCcBXYPeAgCgAciAjEAS2HQ2gDNEAuafAh7AOYBKFAF9UooA

Related Issues:

Contributor guide

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the constructor snippet in the linked TypeScript Playground and compare its behavior with the expected parameter-property interpretation. Trace the parser handling for a modifier followed by a newline, using related issue #28395 for context; done means this form is accepted as a parameter property instead of producing the missing-comma syntax error.

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
Quiet
Clarity
Clearly specified
Newbie friendliness
52/100

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