https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89298
--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> --- It is not clear how that can compile, because both unsigned int g_var =0; and extern unsigned int g_var =0; are g_var definitions, so if that is in multiple TUs, linker should fail to link that. In the other snippet you mention int g_var_a; which is something very different (unless -fno-common), that is a common var and ASAN doesn't instrument those.
