[gcc r8-10086] PR libstdc++/78552 only construct std::locale for C locale once

[Jonathan Wakely]

https://gcc.gnu.org/g:26b070a3f6e5c7ccee7491fb758dba4c72bd7026

commit r8-10086-g26b070a3f6e5c7ccee7491fb758dba4c72bd7026
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Wed Feb 26 09:43:59 2020 +0000

    PR libstdc++/78552 only construct std::locale for C locale once
    
    Backport from mainline
    2019-10-09  Jonathan Wakely  <jwakely@redhat.com>
    
    	PR libstdc++/78552
    	* src/c++98/locale_init.cc (locale::classic()): Do not construct a new
    	locale object for every call.
    	(locale::_S_initialize_once()): Construct C locale here.

Diff:
---
 libstdc++-v3/ChangeLog                | 8 ++++++++
 libstdc++-v3/src/c++98/locale_init.cc | 3 ++-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index ab768b9..8b46372 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,6 +1,14 @@
 2020-02-26  Jonathan Wakely  <jwakely@redhat.com>
 
 	Backport from mainline
+	2019-10-09  Jonathan Wakely  <jwakely@redhat.com>
+
+	PR libstdc++/78552
+	* src/c++98/locale_init.cc (locale::classic()): Do not construct a new
+	locale object for every call.
+	(locale::_S_initialize_once()): Construct C locale here.
+
+	Backport from mainline
 	2020-01-23  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR libstdc++/91947
diff --git a/libstdc++-v3/src/c++98/locale_init.cc b/libstdc++-v3/src/c++98/locale_init.cc
index fb3d8ab..3ee4da3 100644
--- a/libstdc++-v3/src/c++98/locale_init.cc
+++ b/libstdc++-v3/src/c++98/locale_init.cc
@@ -296,7 +296,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   locale::classic()
   {
     _S_initialize();
-    return *(new (&c_locale) locale(_S_classic));
+    return *(const locale*)c_locale;
   }
 
   void
@@ -306,6 +306,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     // One reference for _S_classic, one for _S_global
     _S_classic = new (&c_locale_impl) _Impl(2);
     _S_global = _S_classic;
+    new (&c_locale) locale(_S_classic);
   }
 
   void