have check for GCC version
/* Handling a GCC problem impacting ARMv6-M.*/
#if defined(__GNUC__) && !defined(PORT_IGNORE_GCC_VERSION_CHECK)
#if __GNUC__ > 5
#warning "This compiler has a know problem with Cortex-M0, see bugs: 88167, 88656."
#warning "*** Use GCC version 5 or below ***"
#endif
#endif
From 25.10.2019 this bugs was fixed
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88656
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88167
Can you remove\updated this check in trunk version ?