https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80676
Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2017-05-08 Ever confirmed|0 |1 --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- The fix is trivial: --- a/libstdc++-v3/include/std/sstream +++ b/libstdc++-v3/include/std/sstream @@ -99,7 +99,11 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 explicit basic_stringbuf(ios_base::openmode __mode = ios_base::in | ios_base::out) : __streambuf_type(), _M_mode(__mode), _M_string() - { } + { +#if _GLIBCXX_USE_CXX11_ABI + _M_stringbuf_init(__mode); +#endif + } /** * @brief Starts with an existing string buffer. There was no point calling _M_stringbuf_init for the COW string, because immediately after construction there was no buffer to use. With an SSO string that isn't true.