https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70512
this fixes the canonical type mismatch of 70512. As surmised we don't correct
the ptr-to and ref-to types created during the structure parse when
late-applying the may_alias attribute.
This patch adjusts fixup_attribute_variants to walk the ptr-to and ref-to
lists setting the TYPE_REF_CAN_ALIAS_ALL flag. We also walk those lists for the
main variant itself.
It wasn't clear to me whether decl_attributes (attribs.c) should mark the ptr-to
and ref-to lists of the type having the may_alias attribute applied in place?
By construction, we'll adjust the appropriate canonical types, IIUC.
ok?
nathan
2016-04-04 Nathan Sidwell <nat...@acm.org>
PR c++/70512
* class.c (fixup_may_alias): New.
(fixup_attribute_variants): Call it.
* g++.dg/ext/attribute-may-alias-5.C: New.
Index: cp/class.c
===================================================================
--- cp/class.c (revision 234715)
+++ cp/class.c (working copy)
@@ -1978,6 +1978,21 @@ fixup_type_variants (tree t)
}
}
+/* KLASS is a class that we're applying may_alias to after the body is
+ parsed. Fixup any POINTER_TO and REFERENCE_TO types. The
+ canonical type(s) will be implicitly updated. */
+
+static void
+fixup_may_alias (tree klass)
+{
+ tree t;
+
+ for (t = TYPE_POINTER_TO (klass); t; t = TYPE_NEXT_PTR_TO (t))
+ TYPE_REF_CAN_ALIAS_ALL (t) = true;
+ for (t = TYPE_REFERENCE_TO (klass); t; t = TYPE_NEXT_REF_TO (t))
+ TYPE_REF_CAN_ALIAS_ALL (t) = true;
+}
+
/* Early variant fixups: we apply attributes at the beginning of the class
definition, and we need to fix up any variants that have already been
made via elaborated-type-specifier so that check_qualified_type works. */
@@ -1993,6 +2008,10 @@ fixup_attribute_variants (tree t)
tree attrs = TYPE_ATTRIBUTES (t);
unsigned align = TYPE_ALIGN (t);
bool user_align = TYPE_USER_ALIGN (t);
+ bool may_alias = lookup_attribute ("may_alias", attrs);
+
+ if (may_alias)
+ fixup_may_alias (t);
for (variants = TYPE_NEXT_VARIANT (t);
variants;
@@ -2007,6 +2026,8 @@ fixup_attribute_variants (tree t)
else
TYPE_USER_ALIGN (variants) = user_align;
TYPE_ALIGN (variants) = valign;
+ if (may_alias)
+ fixup_may_alias (variants);
}
}
Index: testsuite/g++.dg/ext/attribute-may-alias-5.C
===================================================================
--- testsuite/g++.dg/ext/attribute-may-alias-5.C (nonexistent)
+++ testsuite/g++.dg/ext/attribute-may-alias-5.C (working copy)
@@ -0,0 +1,9 @@
+// PR c++/70512
+
+struct S
+{
+ S& operator= (int)
+ {
+ return *this;
+ }
+} __attribute__ ((__may_alias__));
