fix: validate named backreferences against existing groups#38
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fix: validate named backreferences against existing groups#38toddr-bot wants to merge 1 commit intocpan-authors:mainfrom
toddr-bot wants to merge 1 commit intocpan-authors:mainfrom
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The parser accepted \k<foo>, \g{name}, (?P=name), (?&name), and
(?P>name) even when no matching named capture group existed anywhere
in the pattern. Perl itself rejects these with "Reference to
nonexistent named group".
Root cause: named_captures hash was only populated during the second
(tree-building) pass, and no validation checked it for backref/recursion
handlers. Numbered backrefs were already validated against maxpar.
Fix: populate named_captures during both passes (SIZE_ONLY uses maxpar,
tree-building uses nparen), then validate all named ref forms during the
second pass. Forward references work correctly because the first pass
has already recorded all group names.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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What
Reject named backreferences and named recursion that reference nonexistent capture groups — matching Perl's own "Reference to nonexistent named group" error.
Why
The parser accepted
\k<foo>,\g{name},(?P=name),(?&name), and(?P>name)without checking whether a named group with that name exists anywhere in the pattern. Perl rejects all of these. Numbered backrefs (\1,\g{N}) were already validated againstmaxpar, but the named equivalents had no validation at all.How
named_capturesduring both parser passes (SIZE_ONLY and tree-building). Previously it was only populated during the second pass, so forward references to later-defined groups would fail validation.RPe_BGROUPerror checks in all 7 named ref/recursion handlers (\k<>,\k'',\k{},\g{name},(?P=),(?&),(?P>)), guarded by!&SIZE_ONLYto match the existing numbered backref pattern.(?&foo)(?<foo>a)work correctly because the first pass records all names.Testing
🤖 Generated with Claude Code
Quality Report
Changes: 2 files changed, 80 insertions(+), 9 deletions(-)
Code scan: clean
Tests: passed (OK)
Branch hygiene: clean
Generated by Kōan post-mission quality pipeline