[Bug c++/77748] pr77550.C fails on arm-none-eabi

["bernd.edlinger at hotmail dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=77748

--- Comment #15 from Bernd Edlinger <bernd.edlinger at hotmail dot de> ---
Thanks.  Again I could reproduce the issue with the assembler flle.
This time it fails in a memcmp.
Apparently the _M_string_length is uninitialized, but used in memcmp.

Can you try this?

Index: pr77550.C
===================================================================
--- pr77550.C   (revision 240540)
+++ pr77550.C   (working copy)
@@ -229,15 +229,17 @@
   struct _Alloc_hider {
     _Alloc_hider(pointer, allocator<char> && = allocator<char>());
   } _M_dataplus;
-  size_type _M_string_length;
+  size_type _M_string_length = 0;
   enum { _S_local_capacity = 15 } _M_local_buf[_S_local_capacity];
-  pointer _M_local_data();
-  void _M_set_length(size_type);
-  basic_string() : _M_dataplus(_M_local_data()) { _M_set_length(0); }
+  basic_string() : _M_dataplus(0) {}
   basic_string(const basic_string &) : _M_dataplus(0) {}
   size_type size() { return _M_string_length; }
   char *data() const {}
 };
+//template<> basic_string<char, std::char_traits<char>,
std::allocator<char>>::
+//_Alloc_hider::_Alloc_hider(char*, std::allocator<char>&&) {}
+extern "C" void
+_ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE12_Alloc_hiderC1EPcOS3_
(...) {}
 }
 template <typename _CharT>
 int operator==(basic_string<_CharT> &p1, const basic_string<_CharT> &p2) {