re PR c++/41785 ([C++0x] ICE on canonical types with variadic templates and CRTP)

Fix PR c++/41785

gcc/cp/ChangeLog:

	PR c++/41785
	* pt.c (template_args_equal): Handle comparison of
	an ARGUMENT_PACK_SELECT node with the arguments node it selects into.
	* cp-tree.def: Fix a typo in the description of TYPE_PACK_EXPANSION.

gcc/testsuite/ChangeLog:
	PR c++/41785
	* gcc/testsuite/g++.dg/cpp0x/variadic96.C: New test.

From-SVN: r153564

gcc/cp/ChangeLog

 2009-10-26  Dodji Seketeli  <dodji@redhat.com>
 
+	PR c++/41785
+	* pt.c (template_args_equal): Handle comparison of
+	an ARGUMENT_PACK_SELECT node with the arguments node it selects into.
+	* cp-tree.def: Fix a typo in the description of TYPE_PACK_EXPANSION.
+
+2009-10-26  Dodji Seketeli  <dodji@redhat.com>
+
 	PR c++/41020
 	* decl.c (decls_match): Use DECL_IS_BUILTIN instead of
 	DECL_BUILT_IN.

gcc/cp/cp-tree.def

@@ -393,7 +393,7 @@ DEFTREECODE (NONTYPE_ARGUMENT_PACK, "nontype_argument_pack", tcc_expression, 1)
      };
 
    The derivation from tuple contains a TYPE_PACK_EXPANSION for the
-   template arguments. Its EXPR_PACK_EXPANSION is "Values&" and its
+   template arguments. Its PACK_EXPANSION_PATTERN is "Values&" and its
    PACK_EXPANSION_PARAMETER_PACKS will contain "Values".  */
 DEFTREECODE (TYPE_PACK_EXPANSION, "type_pack_expansion", tcc_type, 0)
 

gcc/cp/pt.c

@@ -5818,6 +5818,18 @@ template_args_equal (tree ot, tree nt)
 	  return 0;
       return 1;
     }
+  else if (ot && TREE_CODE (ot) == ARGUMENT_PACK_SELECT)
+    {
+      /* We get here probably because we are in the middle of substituting
+         into the pattern of a pack expansion. In that case the
+	 ARGUMENT_PACK_SELECT temporarily replaces the pack argument we are
+	 interested in. So we want to use the initial pack argument for
+	 the comparison.  */
+      ot = ARGUMENT_PACK_SELECT_FROM_PACK (ot);
+      if (nt && TREE_CODE (nt) == ARGUMENT_PACK_SELECT)
+	nt = ARGUMENT_PACK_SELECT_FROM_PACK (nt);
+      return template_args_equal (ot, nt);
+    }
   else if (TYPE_P (nt))
     return TYPE_P (ot) && same_type_p (ot, nt);
   else if (TREE_CODE (ot) == TREE_VEC || TYPE_P (ot))

gcc/testsuite/ChangeLog

+2009-10-26  Dodji Seketeli  <dodji@redhat.com>
+
+	PR c++/41785
+	* gcc/testsuite/g++.dg/cpp0x/variadic96.C: New test.
+
 2009-10-26  Nick Clifton  <nickc@redhat.com>
 
 	* lib/target-supports.exp (check_profiling_available):

gcc/testsuite/g++.dg/cpp0x/variadic96.C

+// Contributed by Dodji Seketeli <dodji@redhat.com>
+// Origin: PR c++/41785
+// { dg-options -std=c++0x }
+
+struct a {};
+
+template < typename T, typename ENCLOSING >
+struct base;
+
+template < typename... T >
+struct derived
+  : public base< T, derived< T... > >...
+{};
+
+template < typename... T>
+struct base< a, derived< T... > >
+{
+  typedef derived< T... >
+          Derived;
+};
+
+int main()
+{
+  derived< a > instance;
+}
+