[PATCH] D32635: [libcxx] regex: fix backreferences in forward assertions

[Peter Ammon via Phabricator via cfe-commits]

pammon created this revision.
Herald added a reviewer: EricWF.

In regex, forward assertions like '(?=stuff)' are implemented by
constructing a child regular expression 'stuff' and matching that.
If the child regular expression contains a backreference, this would
trip an assertion or reference the wrong capture group, because the
child was ignorant of the capture groups of its parent. For example,
/(x)(?=\1)/ would trip an assertion.

Address this by propagating submatches into the child, so that
backreferences reference the correct capture groups. This also allows us
to eliminate the mexp_ field, because the child expression shares the
entire submatch array with the parent.


https://reviews.llvm.org/D32635

Files:
  include/regex
  test/std/re/re.alg/re.alg.match/ecma.pass.cpp

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