[Bug c++/71448] pointer relational comparison fails inside constant expression

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71448

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
The C++ FE would need to substitute &"bar" for bar to make the simplification
valid unless we start relying on undefinedness of pointer wrapping (which we
don't seem to).  Eventually fold_comparison simply misses CONSTANT_CLASS_P
handling alongside DECL_P handling.