microsoft / microsoft/TypeScript

identifierCount may not be correct

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Description

TypeScript Version: 3.2.0-dev.20181114

In parser.ts, there is an identifierCount variable that is incremented every time createIdentifier is called.
Unfortunately, not all createIdentifier calls will result in an identifier in the AST, since some may have happened during speculative parsing. It may be necessary to reset identifierCount after speculative parsing fails.

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Research direction

Start in parser.ts by reading identifierCount and the createIdentifier call sites, then trace the speculative parsing paths that can fail. Confirm how failed speculation affects the count and identify existing parser tests that cover those paths. Done means identifierCount reflects identifiers retained in the AST after speculative parsing.

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
45/100

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