[Bug libstdc++/54392] [4.6/4.7/4.8 Regression] std::string::assign() fails to update length

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54392

--- Comment #12 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-08-29 
16:53:02 UTC ---
Nope, unfortunately I remembered correctly: if we call _M_replace_safe for
these cases the new chars are copied at the very end. At that point, the
destination string is already reallocated but in these cases it's also the
source string and __s doesn't point anymore to it. _M_replace_safe is exactly
for when __s remains a valid address for the source chars from beginning to end
of the whole operation.