https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82644
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- While I'm on the subject, we fail to import the special functions into the global namespace in <math.h> (because the wrong macro is checked): #include <math.h> namespace test { using std::beta; // OK using ::beta; // ERROR } specfun.cc:4:11: error: ‘::beta’ has not been declared using ::beta; // ERROR ^~~~ And we don't properly document IS 29124 support, and implementation-defined behaviour.