https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91815
--- Comment #3 from Eric Botcazou <ebotcazou at gcc dot gnu.org> --- The fixlet slightly breaks Objective-C: +FAIL: objc.dg/headers.m -fgnu-runtime (test for excess errors) +FAIL: objc.dg/id-1.m -fgnu-runtime (test for errors, line 4) +FAIL: objc.dg/id-1.m -fgnu-runtime (test for warnings, line ) It looks like the Objective-C compiler uses the code to deal with declarations conflicting with (or shadowing) the declarations of the basic types in objc.h.