Unsupported RCPE features

[Vovan-VE]

Illegal/unsupported escape sequense:

• \g... family: \gn, \g{N}, \g{-N}, \g<N>, \g<-N>, \g'N', \g'-N', \g<name>, \g'name', \g{name}
• \k{name}
• \N, \R, \K, \C

This named group reference is not supported

• \k<name>, \k'name'
• (?P=name)

Unclosed options group

• (?N), (?+N), (?-N), where N is a group number (absolute or relative)
• (?P>name), (?&name) - same error message
• (?|...) - same error message

Conditional references are not supported

• (?(cond)yes|no)

[cburschka-pwc]

This also includes the /x modifier (which ignores whitespace and inline comments in the pattern), leading to a) false-positive errors in comments and b) marking \\# as a redundant escape, even though it is required when including a literal # in an extended pattern.

[juliangut]

I'm facing the problem with backreferences

Is this issue of any priority?