https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124231
--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> --- So back to the original reported issue. The problem is the line markers like: # 876 "chip/stm32_ethernet.c" 3 4 say this: ‘3’ This indicates that the following text comes from a system header file, so certain warnings should be suppressed. ‘4’ This indicates that the following text should be treated as being wrapped in an implicit extern "C" block. Which means it comes from a system header. Why I have no idea since I don't have the original source. Maybe a macro that expands this. This is why you need -Wsystem-headers option. GCC is working as designed based on the input here.
