[Bug libstdc++/120029] Dangling iterator usage in std::filesystem::path::operator+=(const std::filesystem::path &p) when this == p

[redi at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120029

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The simplest fix is just:

--- a/libstdc++-v3/src/c++17/fs_path.cc
+++ b/libstdc++-v3/src/c++17/fs_path.cc
@@ -880,6 +880,9 @@ path::operator+=(const path& p)
       return *this;
     }

+  if (&p == this) [[unlikely]]
+    return *this += p.native();
+
 #if _GLIBCXX_FILESYSTEM_IS_WINDOWS
   if (_M_type() == _Type::_Root_name
       || (_M_type() == _Type::_Filename && _M_pathname.size() == 1))