JS/TS detect all syntax errors in RegExps.

[pygy]

VSCode detects some syntax errors in RegExps in JS (e.g. /[/ gets squiggles and a helpful message on hover), but it misses many others

As you know, in JS (And thus TS), Unicode regexps have a grammar that's incompatible with legacy, non-u ones, and it should be taken into account.

All of these are invalid, but are not marked as such:

/\b+/ // can't quantify assertions

/^+/ // can't quantify assertions

/$+/ // can't quantify assertions

/(?<=)+/ // can't quantify assertions

/(?=)+/u // can't quantify look ahead assertions in u mode

/]/u // syntax characters must be escaped in u mode

/{a}/u // syntax characters must be escaped in u mode

/\-/u // non-syntax characters must not be escaped in u mode

/\1/u // orphan back reference in u mode

/\k<OrphanNameRefWithUFlag>/u

[pygy]

As mentioned in microsoft/vscode#148612, I'm working on a RegExp tokenizer that may be useful to implement this.

[andrewbranch]

Duplicate of #3432

[typescript-bot]

This issue has been marked as a 'Duplicate' and has seen no recent activity. It has been automatically closed for house-keeping purposes.