[committed] libstdc++: Make operator<< for stacktraces less templated (LWG 3515)

[Jonathan Wakely via Gcc-patches]

Tested x86_64-linux. Pushed to trunk.

-- >8--

This change was approved for C++23 last month.

libstdc++-v3/ChangeLog:

        * include/std/stacktrace (operator<<): Only output to narrow
        ostreams (LWG 3515).
        * testsuite/19_diagnostics/stacktrace/synopsis.cc:
---
 libstdc++-v3/include/std/stacktrace           | 38 +++++++++----------
 .../19_diagnostics/stacktrace/synopsis.cc     | 11 +++---
 2 files changed, 22 insertions(+), 27 deletions(-)

diff --git a/libstdc++-v3/include/std/stacktrace 
b/libstdc++-v3/include/std/stacktrace
index ec3335e89d8..83c6463b0d8 100644
--- a/libstdc++-v3/include/std/stacktrace
+++ b/libstdc++-v3/include/std/stacktrace
@@ -165,9 +165,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return __state;
     }
 
-    template<typename _CharT, typename _Traits>
-      friend basic_ostream<_CharT, _Traits>&
-      operator<<(basic_ostream<_CharT, _Traits>&, const stacktrace_entry&);
+    friend ostream&
+    operator<<(ostream&, const stacktrace_entry&);
 
     bool
     _M_get_info(string* __desc, string* __file, int* __line) const
@@ -720,25 +719,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     noexcept(noexcept(__a.swap(__b)))
     { __a.swap(__b); }
 
-  template<typename _CharT, typename _Traits>
-    inline basic_ostream<_CharT, _Traits>&
-    operator<<(basic_ostream<_CharT, _Traits>& __os,
-              const stacktrace_entry& __f)
-    {
-      string __desc, __file;
-      int __line;
-      if (__f._M_get_info(&__desc, &__file, &__line))
-       {
-         __os.width(4);
-         __os << __desc << " at " << __file << ':' << __line;
-       }
-      return __os;
-    }
+  inline ostream&
+  operator<<(ostream& __os, const stacktrace_entry& __f)
+  {
+    string __desc, __file;
+    int __line;
+    if (__f._M_get_info(&__desc, &__file, &__line))
+      {
+       __os.width(4);
+       __os << __desc << " at " << __file << ':' << __line;
+      }
+    return __os;
+  }
 
-  template<typename _CharT, typename _Traits, typename _Allocator>
-    inline basic_ostream<_CharT, _Traits>&
-    operator<<(basic_ostream<_CharT, _Traits>& __os,
-              const basic_stacktrace<_Allocator>& __st)
+  template<typename _Allocator>
+    inline ostream&
+    operator<<(ostream& __os, const basic_stacktrace<_Allocator>& __st)
     {
       for (stacktrace::size_type __i = 0; __i < __st.size(); ++__i)
        {
diff --git a/libstdc++-v3/testsuite/19_diagnostics/stacktrace/synopsis.cc 
b/libstdc++-v3/testsuite/19_diagnostics/stacktrace/synopsis.cc
index 72582fa53c6..262abea21ec 100644
--- a/libstdc++-v3/testsuite/19_diagnostics/stacktrace/synopsis.cc
+++ b/libstdc++-v3/testsuite/19_diagnostics/stacktrace/synopsis.cc
@@ -28,13 +28,12 @@ namespace std
   template<class Allocator>
     string to_string(const basic_stacktrace<Allocator>& st);
 
-  template<class charT, class traits>
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os, const stacktrace_entry& f);
+  ostream&
+  operator<<(ostream& os, const stacktrace_entry& f);
 
-  template<class charT, class traits, class Allocator>
-    basic_ostream<charT, traits>&
-    operator<<(basic_ostream<charT, traits>& os, const 
basic_stacktrace<Allocator>& st);
+  template<class Allocator>
+    ostream&
+    operator<<(ostream& os, const basic_stacktrace<Allocator>& st);
 
   namespace pmr {
     using stacktrace = 
basic_stacktrace<polymorphic_allocator<stacktrace_entry>>;
-- 
2.38.1