> In practice I dare you to find compiler documentation for each implementation defined behavior.
For gcc there is this:
https://gcc.gnu.org/onlinedocs/gcc/C-Implementation.html
No idea how complete it is. Also a lot of stuff is architecture/platform specific, not compiler specific, so you won't find it in the general compiler docs but you have to look at the psABI.
In practice I dare you to find compiler documentation for each implementation defined behavior.
https://timsong-cpp.github.io/cppwp/n4868/intro.defs#defns.u...
https://timsong-cpp.github.io/cppwp/n4868/intro.defs#defns.i...
edit:
C wording:
https://cigix.me/c17#J.1
https://cigix.me/c17#J.3