[Bug libstdc++/110968] format out of bounds read on format("{:05L}",-1.f)

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110968

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
--- a/libstdc++-v3/include/std/format
+++ b/libstdc++-v3/include/std/format
@@ -1634,7 +1634,8 @@ namespace __format
                __wstr = _M_localize(__str, __expc, __fc.locale());
              else
                __wstr = _M_localize(__str, __expc, __loc.value());
-             __str = __wstr;
+             if (!__wstr.empty())
+               __str = __wstr;
            }

          size_t __width = _M_spec._M_get_width(__fc);