diff mbox

[C++] fix canonical type ICE

Message ID 555F7264.7030708@acm.org
State New
Headers show

Commit Message

Nathan Sidwell May 22, 2015, 6:16 p.m. UTC 
On 05/21/15 21:47, Jason Merrill wrote:
> How about adding may_alias support to the code a bit lower down that copies the
> abi_tag attribute?

Good idea.  This keeps the non-copy behavior when the attribute is the last on 
the source attribute list, and fixes up the case for when there are both 
may_alias and abi_tag.

booted and tested on x86_64-linux

ok?


nathan

Comments

Jason Merrill May 23, 2015, 8:24 p.m. UTC | #1 
OK, thanks.

Jason
diff mbox

Patch

2015-05-22  Nathan Sidwell  <nathan@acm.org>

	PR c++/65936
	* pt.c (lookup_template_class_1): Copy may_alias attribute too.

	PR c++/65936
	* g++.dg/template/pr65936.C: New.

Index: cp/pt.c
===================================================================
--- cp/pt.c	(revision 223503)
+++ cp/pt.c	(working copy)
@@ -7905,15 +7905,22 @@  lookup_template_class_1 (tree d1, tree a
       if (OVERLOAD_TYPE_P (t)
 	  && !DECL_ALIAS_TEMPLATE_P (gen_tmpl))
 	{
-	  if (tree attributes
-	      = lookup_attribute ("abi_tag", TYPE_ATTRIBUTES (template_type)))
+	  static const char *tags[] = {"abi_tag", "may_alias"};
+
+	  for (unsigned ix = 0; ix != 2; ix++)
 	    {
-	      if (!TREE_CHAIN (attributes))
+	      tree attributes
+		= lookup_attribute (tags[ix], TYPE_ATTRIBUTES (template_type));
+
+	      if (!attributes)
+		;
+	      else if (!TREE_CHAIN (attributes) && !TYPE_ATTRIBUTES (t))
 		TYPE_ATTRIBUTES (t) = attributes;
 	      else
 		TYPE_ATTRIBUTES (t)
-		  = build_tree_list (TREE_PURPOSE (attributes),
-				     TREE_VALUE (attributes));
+		  = tree_cons (TREE_PURPOSE (attributes),
+			       TREE_VALUE (attributes),
+			       TYPE_ATTRIBUTES (t));
 	    }
 	}
 
Index: testsuite/g++.dg/template/pr65936.C
===================================================================
--- testsuite/g++.dg/template/pr65936.C	(revision 0)
+++ testsuite/g++.dg/template/pr65936.C	(working copy)
@@ -0,0 +1,21 @@ 
+// checking ICE in canonical typing
+
+class A;
+
+template <typename> struct B
+{
+  typedef A type;
+};
+
+template <class T> class C
+  : public B<T>::type
+{
+} __attribute__ ((__may_alias__));
+
+class A
+{
+  operator const C<int> &()
+  {
+    return *static_cast<const C<int> *> (this);
+  }
+};