Constructor locale(const char* std_name), when called with name of nonuniform locale (like "LC_CTYPE=...;LC_COLLATE=...;..."), can create locale with incorrect content of some its facets: these facets differ from facets of locale, created via locale(const locale& other, const char* std_name, category) with subsequent replacing of categories. While this locale has same name as argument of locale(const char* std_name).
This behaviour contradicts description of member-function name() (22.1.1.3, p5): If *this has a name, then locale(name().c_str()) is equivalent to *this. Example below demonstrates contradiction of this statement on curr_symbol() property of moneypunct<wchar_t> facet: #include <locale> #include <cassert> int main() { using namespace std; locale loc(locale("C"), "en_GB.utf8", locale::monetary); const moneypunct<wchar_t>& mp = use_facet<moneypunct<wchar_t> >(loc); locale loc_copy(loc.name().c_str()); const moneypunct<wchar_t>& mp_copy = use_facet<moneypunct<wchar_t> >(loc_copy); assert(mp.curr_symbol() == mp_copy.curr_symbol()); return 0; } It seems, the source of the problem is a method of filling properties of named locale. E.g., for moneypunct<wchar_t> facet, the method performs the following: 1)sets the current POSIX locale with given name, 2)sets some properties of C++ locale, using __nl_langinfo_l() function call, 3)the rest properties of C++ locale are obtained from char-versions of them using mbsrtowcs()-like functions. But mbsrtowcs() use current LC_CTYPE category, which name may differ from the name of LC_MONETARY category in nonuniform locale. So mbsrtowcs() assumes that string, passed to it, belongs to one charset(according to LC_TYPE category name), while it belongs to the another (according to LC_MONETARY category name). This fact entails wrong property value, obtained via such call to mbsrtowcs(). Up to garbage, because implementation doesn't verify result of mbsrtowcs(), which doesn't set terminating '\0' in case of error. The fact, that the implementation doest't verify result of mbsrtowcs(), also seems strange - absence of terminating '\0' may lead to SIGFAULT. -- Summary: locale(const char* std_name) can create invalid facets for nonuniform locale Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: tsyvarev at ispras dot ru http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40184