Earlier quoted context omitted.
The problem is that embedded compilers are not known for keeping up with the standards. The only hope is that the moves to GCC and Clang continue.
No one cares about the standards. We only care about getting things done by writing regular C code that works.
Every compiler you have used operates at a bare minimum on the C standard. That’s why they are often advertised (if not GCC/Clang which are assumed to be up to date) as “C(89|99|11|17) compliant.” “Code that works” is code which is operates under constraints and guarantees specified by a standard, anything else is undefined or unportable.