https://gcc.gnu.org/bugzilla/show_bug.cgi?id=39159
wipedout at yandex dot ru changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |wipedout at yandex dot ru --- Comment #4 from wipedout at yandex dot ru --- Tons of warnings like this arise when porting code from Visual C++ to gcc. Visual C++ supports "interface" keyword and you can have "interface Interface;" many times - both above and before the actual definition. "interface" has to be mapped to exactly "struct __attribute__ ((visibility ("default")))" and so the code which originally compiled no problem causes hundreds of warnings with gcc.