https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54319
--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
It is the code in call.c that makes a difference:
if (is_really_empty_class (type, /*ignore_vptr*/true))
{
/* Avoid copying empty classes. */
val = build2 (COMPOUND_EXPR, type, arg, to);
suppress_warning (val, OPT_Wunused);
}
else if (tree_int_cst_equal (TYPE_SIZE (type), TYPE_SIZE (as_base)))
{
if (is_std_init_list (type)
&& conv_binds_ref_to_prvalue (convs[1]))
warning_at (loc, OPT_Winit_list_lifetime,
"assignment from temporary %<initializer_list%> does "
"not extend the lifetime of the underlying array");
arg = cp_build_fold_indirect_ref (arg);
val = build2 (MODIFY_EXPR, TREE_TYPE (to), to, arg);
}
else
{
/* We must only copy the non-tail padding parts. */
tree arg0, arg2, t;
tree array_type, alias_set;
arg2 = TYPE_SIZE_UNIT (as_base);
to = cp_stabilize_reference (to);
arg0 = cp_build_addr_expr (to, complain);
array_type = build_array_type (unsigned_char_type_node,
build_index_type
(size_binop (MINUS_EXPR,
arg2, size_int (1))));
alias_set = build_int_cst (build_pointer_type (type), 0);
t = build2 (MODIFY_EXPR, void_type_node,
build2 (MEM_REF, array_type, arg0, alias_set),
build2 (MEM_REF, array_type, arg, alias_set));
val = build2 (COMPOUND_EXPR, TREE_TYPE (to), t, to);
suppress_warning (val, OPT_Wunused);
}
if we do the middle one only, we get the correct type.
I won't be able to debug this any further. But I suspect because we are
lowering the AST too early, we don't do the correct type dealing here due to
the COMPOUND_EXPR.
