https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116130
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Seems we actually implement it that way already, or at least sometimes.
build_conditional_expr has
/* Quickly detect the usual case where op1 and op2 have the same type
after promotion. */
if (TYPE_MAIN_VARIANT (type1) == TYPE_MAIN_VARIANT (type2))
{
if (type1 == type2)
result_type = type1;
else
result_type = TYPE_MAIN_VARIANT (type1);
}
which would do the wrong thing and
else if (code1 == POINTER_TYPE && code2 == POINTER_TYPE)
{
...
if (comp_target_types (colon_loc, type1, type2))
result_type = common_pointer_type (type1, type2);
which would merge them.
All I want to say is that there are big chances of this breaking real-world
code if somebody decides to add the new standard attributes to decls.
