c-family: char8_t and aliasing in C vs C++ [PR111884]
In the PR, Joseph says that in C char8_t is not a distinct type. So
we should behave as if it can alias anything, like ordinary char.
In C, unsigned_char_type_node == char8_type_node, so with this patch
we return 0 instead of -1. And the following comment says:
/* The C standard guarantees that any object may be accessed via an
lvalue that has narrow character type (except char8_t). */
if (t == char_type_node
|| t == signed_char_type_node
|| t == unsigned_char_type_node)
return 0;
Which appears to be wrong, so I'm adjusting that as well.
PR c/111884
gcc/c-family/ChangeLog:
* c-common.cc (c_common_get_alias_set): Return -1 for char8_t only
in C++.