From: Jonathan Wakely <jwakely@redhat.com>
Date: Tue, 30 Jan 2024 14:48:28 +0000 (+0000)
Subject: libstdc++: Fix effects of combining locales [PR108323]
X-Git-Tag: basepoints/gcc-16~8772
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=947a9c801e818f412ad4c669a49297c3512b3a6e;p=thirdparty%2Fgcc.git

libstdc++: Fix effects of combining locales [PR108323]

This fixes a bug in locale::combine where we fail to meet the standard's
requirement that the result is unnamed. It also implements two library
issues related to the names of combined locales (2295 and 3676).

libstdc++-v3/ChangeLog:

	PR libstdc++/108323
	* include/bits/locale_classes.tcc (locale(const locale&, Facet*)):
	Return a copy of the first argument when the facet pointer is
	null, as per LWG 2295.
	(locale::combine): Ensure the result is unnamed.
	* src/c++11/localename.cc (_M_replace_categories): Ignore
	whether the second locale has a name when cat == none, as per
	LWG 3676.
	* src/c++98/locale.cc (_M_install_facet): Use __builtin_expect
	to predict that the facet pointer is non-null.
	* testsuite/22_locale/locale/cons/names.cc: New test.
---

diff --git a/libstdc++-v3/include/bits/locale_classes.tcc b/libstdc++-v3/include/bits/locale_classes.tcc
index 63097582decf..00eeb7dd9f89 100644
--- a/libstdc++-v3/include/bits/locale_classes.tcc
+++ b/libstdc++-v3/include/bits/locale_classes.tcc
@@ -44,6 +44,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     locale::
     locale(const locale& __other, _Facet* __f)
     {
+      // _GLIBCXX_RESOLVE_LIB_DEFECTS
+      // 2295. Locale name when the provided Facet is a nullptr
+      if (__builtin_expect(!__f, 0))
+	{
+	  _M_impl = __other._M_impl;
+	  _M_impl->_M_add_reference();
+	  return;
+	}
+
       _M_impl = new _Impl(*__other._M_impl, 1);
 
       __try
@@ -72,6 +81,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  __tmp->_M_remove_reference();
 	  __throw_exception_again;
 	}
+      delete[] __tmp->_M_names[0];
+      __tmp->_M_names[0] = 0;   // Unnamed.
       return locale(__tmp);
     }
 
@@ -163,7 +174,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   */
   template<typename _Facet>
     inline bool
-    has_facet(const locale& __loc) throw()
+    has_facet(const locale& __loc) _GLIBCXX_USE_NOEXCEPT
     {
 #if __cplusplus >= 201103L
       static_assert(__is_base_of(locale::facet, _Facet),
diff --git a/libstdc++-v3/src/c++11/localename.cc b/libstdc++-v3/src/c++11/localename.cc
index cde94ec6e19f..909cf4c66d34 100644
--- a/libstdc++-v3/src/c++11/localename.cc
+++ b/libstdc++-v3/src/c++11/localename.cc
@@ -326,7 +326,9 @@ const int num_facets = (
   _M_replace_categories(const _Impl* __imp, category __cat)
   {
     category __mask = 1;
-    if (!_M_names[0] || !__imp->_M_names[0])
+    // _GLIBCXX_RESOLVE_LIB_DEFECTS
+    // 3676. Name of locale composed using std::locale::none
+    if (!_M_names[0] || (__cat != none && !__imp->_M_names[0]))
       {
 	if (_M_names[0])
 	  {
diff --git a/libstdc++-v3/src/c++98/locale.cc b/libstdc++-v3/src/c++98/locale.cc
index 3749408115ea..0e7533e1e152 100644
--- a/libstdc++-v3/src/c++98/locale.cc
+++ b/libstdc++-v3/src/c++98/locale.cc
@@ -323,7 +323,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   locale::_Impl::
   _M_install_facet(const locale::id* __idp, const facet* __fp)
   {
-    if (__fp)
+    if (__builtin_expect(__fp != 0, 1))
       {
 	size_t __index = __idp->_M_id();
 
diff --git a/libstdc++-v3/testsuite/22_locale/locale/cons/names.cc b/libstdc++-v3/testsuite/22_locale/locale/cons/names.cc
new file mode 100644
index 000000000000..2a9cfe4c14da
--- /dev/null
+++ b/libstdc++-v3/testsuite/22_locale/locale/cons/names.cc
@@ -0,0 +1,61 @@
+// { dg-do run }
+
+#include <locale>
+#include <testsuite_hooks.h>
+
+void
+test_pr108323()
+{
+  std::locale named = std::locale::classic();
+  std::locale unnamed = named.combine<std::ctype<char> >(named);
+
+  // Bug libstdc++/108323 - combine does not change the locale name
+  VERIFY( unnamed.name() == "*" );
+}
+
+void
+test_lwg2295()
+{
+  std::locale named = std::locale::classic();
+  std::locale unnamed(named, &std::use_facet<std::ctype<char> >(named));
+  VERIFY( unnamed.name() == "*" );
+
+  // LWG 2295. Locale name when the provided Facet is a nullptr
+  std::locale loc(named, (std::ctype<char>*)0);
+  VERIFY( loc.name() != "*" );
+  VERIFY( loc.name() == named.name() );
+}
+
+void
+test_lwg3676()
+{
+  std::locale named = std::locale::classic();
+  std::locale unnamed = named.combine<std::ctype<char> >(named);
+  std::locale combo;
+
+  // LWG 3676. Name of locale composed using std::locale::none
+
+  combo = std::locale(named, named, std::locale::numeric);
+  VERIFY( combo.name() != "*" );
+  combo = std::locale(named, named, std::locale::none);
+  VERIFY( combo.name() != "*" );
+  combo = std::locale(named, unnamed, std::locale::numeric);
+  VERIFY( combo.name() == "*" );
+  combo = std::locale(named, unnamed, std::locale::none);
+  VERIFY( combo.name() != "*" );
+  combo = std::locale(unnamed, named, std::locale::numeric);
+  VERIFY( combo.name() == "*" );
+  combo = std::locale(unnamed, named, std::locale::none);
+  VERIFY( combo.name() == "*" );
+  combo = std::locale(unnamed, unnamed, std::locale::numeric);
+  VERIFY( combo.name() == "*" );
+  combo = std::locale(unnamed, unnamed, std::locale::none);
+  VERIFY( combo.name() == "*" );
+}
+
+int main()
+{
+  test_pr108323();
+  test_lwg2295();
+  test_lwg3676();
+}