TS1508: Unexpected '?'. Did you mean to escape it with backslash? shouldn't report even with `v` flag · Microsoft/TypeScript#62707

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BugDomain: ParserHelp Wanted

描述

TS1508, "Did you mean to escape it with backslash?"

This changed between versions ______ and _______
This changed in https://github.com/microsoft/TypeScript/pull/55600 which introduced regular expression syntax checking
This is the behavior in every version I tried, and I reviewed the FAQ for entries about _________
I was unable to test this on prior versions because _______

/[?&]/v

The error "TS1508: Unexpected '?'. Did you mean to escape it with backslash?" is given.

No error because ? doesn't need to be escaped in a character class even with a v flag.

Other characters like { do need escaping with the v flag, but ? gets no runtime errors, so I don't see why this has to err now.

技术栈: typescript
领域: toolingdeveloper experience
议题类型: bug
难度: 3
预计时间: 1-3 hours
活动状态: fresh
清晰度: clear
前置要求: Understanding of regular expression syntaxFamiliarity with TypeScript compiler codebase
新手友好度: 40
研究方向: Start by examining the regular expression syntax checking logic introduced in PR #55600. Look at the checker code that reports TS1508, likely in src/compiler/checker.ts or a dedicated regex validation file. Investigate how the `v` flag affects character class parsing; specifically, the `?` character should be allowed unescaped inside character classes. The fix would involve modifying the regex validation to exempt `?` from requiring escaping when inside character classes with the `v` flag. Reference the playground link and ensure the fix aligns with ECMAScript specification for `v` flag.