.. testing completed OK.
Just in case it wasn't obvious in my previous messages, when we are
calling check_for_uninitialized_const_var from
potential_constant_expression_1 we can't use CP_TYPE_CONST_P as gate for
emitting diagnostic - as just discovered - neither we can use
var_in_constexpr_fn, which would cause many regressions for variables in
constexpr functions, I remember cpp1y/pr63996.C for example.
Conservatively, !DECL_NONTRIVIALLY_INITIALIZED_P supplemented by
default_init_uninitialized_part appears to work fine.
Thanks,
Paolo.
