https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80711
--- Comment #6 from Martin Sebor <msebor at gcc dot gnu.org> --- You're right, there is a substantial difference between attributes const/pure and constness in the C/C++ sense. A warning that detects missing const on member functions (i.e., this request) is implementable in the C++ front end, while one that also considers accesses to the state of the object would have to be implemented in the middle end (like -Wsuggest-attribute). Only there is it possible to tell if a pointer dereference accesses *this. As an aside, a risk with enabling -Wsuggest-attribute= is that GCC doesn't detect accesses that are invalid in pure functions (like to globals), or any other misuses in functions declared with any of the suggested attributes. Since what is and isn't safe isn't always clear to everyone, it's easy to get it wrong. Once the detection is implemented, hopefully for GCC 11 (pr18487), using attributes pure and const will be a lot safer. But that's independent of improving const-correctness.
