P2301R1 Add a pmr alias for std::stacktrace

Author: jensmaurer

source/utilities.tex

@@ -22404,6 +22404,10 @@
     basic_ostream<charT, traits>&
       operator<<(basic_ostream<charT, traits>& os, const basic_stacktrace<Allocator>& st);
 
+  namespace pmr {
+    using stacktrace = basic_stacktrace<polymorphic_allocator<stacktrace_entry>>;
+  }
+
   // \ref{stacktrace.basic.hash}, hash support
   template<class T> struct hash;
   template<> struct hash<stacktrace_entry>;