> 2018-01-30 Jan Hubicka <hubi...@ucw.cz>
>
> gcc:
> PR lto/83954
> * lto-symtab.c (warn_type_compatibility_p): Silence false positive
> for type match warning on arrays of pointers.
>
> gcc/testsuite:
> PR lto/83954
> * gcc.dg/lto/pr83954.h: New testcase.
> * gcc.dg/lto/pr83954_0.c: New testcase.
> * gcc.dg/lto/pr83954_1.c: New testcase.
That being said, I'm not convinced that the patch is correct:
+ /* Alias sets of arrays are the same as alias sets of the inner
+ types. */
+ while (TREE_CODE (t1) == ARRAY_TYPE && TREE_CODE (t2) == ARRAY_TYPE)
+ {
+ t1 = TREE_TYPE (t1);
+ t2 = TREE_TYPE (t2);
+ }
That's not always true, see get_alias_set:
/* Unless the language specifies otherwise, treat array types the
same as their components. This avoids the asymmetry we get
through recording the components. Consider accessing a
character(kind=1) through a reference to a character(kind=1)[1:1].
Or consider if we want to assign integer(kind=4)[0:D.1387] and
integer(kind=4)[4] the same alias set or not.
Just be pragmatic here and make sure the array and its element
type get the same alias set assigned. */
else if (TREE_CODE (t) == ARRAY_TYPE
&& (!TYPE_NONALIASED_COMPONENT (t)
|| TYPE_STRUCTURAL_EQUALITY_P (t)))
set = get_alias_set (TREE_TYPE (t));
and gnat.dg/lto20.adb is very likely in the TYPE_NONALIASED_COMPONENT case.
--
Eric Botcazou
