https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83164
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |rguenth at gcc dot gnu.org
Target Milestone|--- |8.0
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
comparison verification has
/* For comparisons we do not have the operations type as the
effective type the comparison is carried out in. Instead
we require that either the first operand is trivially
convertible into the second, or the other way around.
Because we special-case pointers to void we allow
comparisons of pointers with the same mode as well. */
if (!useless_type_conversion_p (op0_type, op1_type)
&& !useless_type_conversion_p (op1_type, op0_type)
&& (!POINTER_TYPE_P (op0_type)
|| !POINTER_TYPE_P (op1_type)
|| TYPE_MODE (op0_type) != TYPE_MODE (op1_type)))
{
which works around a similar issue there (the comment is outdated).
IIRC the following is to not wreck targets with function descriptors
where the conversion generates code(?) I'd be very happy to get rid
of this special case and/or if this is really the case make it
more explicit somehow.
bool
useless_type_conversion_p (tree outer_type, tree inner_type)
{
/* Do the following before stripping toplevel qualifiers. */
if (POINTER_TYPE_P (inner_type)
&& POINTER_TYPE_P (outer_type))
{
...
/* Do not lose casts to function pointer types. */
if ((TREE_CODE (TREE_TYPE (outer_type)) == FUNCTION_TYPE
|| TREE_CODE (TREE_TYPE (outer_type)) == METHOD_TYPE)
&& !(TREE_CODE (TREE_TYPE (inner_type)) == FUNCTION_TYPE
|| TREE_CODE (TREE_TYPE (inner_type)) == METHOD_TYPE))
return false;
