From: Luca Bacci <luca.bacci982@gmail.com>
Date: Tue, 17 Dec 2024 18:57:30 +0000 (+0000)
Subject: libstdc++: Call regex_traits::transform_primary() only when necessary [PR98723]
X-Git-Tag: basepoints/gcc-16~3236
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eb339c29ee42aa59591fc50d6d8a1ab903d2a3fe;p=thirdparty%2Fgcc.git

libstdc++: Call regex_traits::transform_primary() only when necessary [PR98723]

This is both a performance optimization and a partial fix for PR 98723.

This commit fixes the issue for bracket expressions that do not depend
on the locale's collation facet. Examples:

 * Character ranges ([a-z]) when std::regex::collate is not set
 * Character classes ([:alnum:])
 * Individual characters ([abc])

Signed-off-by: Luca Bacci <luca.bacci982@gmail.com>

libstdc++-v3/ChangeLog:

	PR libstdc++/98723
	* include/bits/regex_compiler.tcc (_BracketMatcher::_M_apply):
	Only use transform_primary when an equivalence set is used.
---

diff --git a/libstdc++-v3/include/bits/regex_compiler.tcc b/libstdc++-v3/include/bits/regex_compiler.tcc
index 9c5a46a47cd0..5037195ca17a 100644
--- a/libstdc++-v3/include/bits/regex_compiler.tcc
+++ b/libstdc++-v3/include/bits/regex_compiler.tcc
@@ -611,10 +611,13 @@ namespace __detail
 	    return true;
 	if (_M_traits.isctype(__ch, _M_class_set))
 	  return true;
-	if (std::find(_M_equiv_set.begin(), _M_equiv_set.end(),
-		      _M_traits.transform_primary(&__ch, &__ch+1))
-	    != _M_equiv_set.end())
-	  return true;
+	if (!_M_equiv_set.empty())
+	  {
+	    auto __x = _M_traits.transform_primary(&__ch, &__ch+1);
+	    auto __p = std::find(_M_equiv_set.begin(), _M_equiv_set.end(), __x);
+	    if (__p != _M_equiv_set.end())
+	      return true;
+	  }
 	for (auto& __it : _M_neg_class_set)
 	  if (!_M_traits.isctype(__ch, __it))
 	    return true;