2008-07-15  Richard Guenther  <rguenther@suse.de>

	PR middle-end/36369
	* c-common.c (strict_aliasing_warning): Do not warn for
	TYPE_REF_CAN_ALIAS_ALL pointers.
	(c_common_get_alias_set): may_alias types are not special.
	* tree.c (build_pointer_type_for_mode): Look up the may_alias
	attribute and set can_ref_all accordingly.
	(build_reference_type_for_mode): Likewise.
	* doc/extend.texi (may_alias): Clarify.

	* gcc.dg/Wstrict-aliasing-bogus-ref-all.c: New testcase.

From-SVN: r137843