https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104603
--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
-DA just changes inlining.
This is just an inlining mess which you can see from the diagnostic on the
trunk:
In member function 'bool Base::isX() const',
inlined from 'bool Base::operator==(const Base&) const' at <source>:16:15,
inlined from 'bool X::operator==(const X&) const' at <source>:10:51,
inlined from 'bool Base::operator==(const Base&) const' at <source>:16:63,
inlined from 'bool X::operator==(const X&) const' at <source>:10:51,
inlined from 'void f()' at <source>:24:11:
<source>:4:29: warning: array subscript 2 is outside array bounds of 'X [1]'
[-Warray-bounds]
4 | bool isX() const { return isX_; }
| ^~~~
The warning happens before some other optimizations happen which allows GCC to
prove the function will just always return false ...
