re PR c++/40687 ([C++0x]: error with auto and 7.1.6.4/7 in N2914)

	PR c++/40687
	* pt.c (do_auto_deduction): Diagnose inconsistent deduction.

From-SVN: r153855

gcc/cp/ChangeLog

+2009-11-03  Jason Merrill  <jason@redhat.com>
+
+	PR c++/40687
+	* pt.c (do_auto_deduction): Diagnose inconsistent deduction.
+
 2009-11-02  Dodji Seketeli  <dodji@redhat.com>
 
 	PR c++/37093

gcc/cp/pt.c

@@ -17796,10 +17796,7 @@ make_args_non_dependent (VEC(tree,gc) *args)
 tree
 make_auto (void)
 {
-  tree au;
-
-  /* ??? Is it worth caching this for multiple autos at the same level?  */
-  au = cxx_make_type (TEMPLATE_TYPE_PARM);
+  tree au = cxx_make_type (TEMPLATE_TYPE_PARM);
   TYPE_NAME (au) = build_decl (BUILTINS_LOCATION,
 			       TYPE_DECL, get_identifier ("auto"), au);
   TYPE_STUB_DECL (au) = TYPE_NAME (au);
@@ -17877,6 +17874,19 @@ do_auto_deduction (tree type, tree init, tree auto_node)
       return error_mark_node;
     }
 
+  /* If the list of declarators contains more than one declarator, the type
+     of each declared variable is determined as described above. If the
+     type deduced for the template parameter U is not the same in each
+     deduction, the program is ill-formed.  */
+  if (TREE_TYPE (auto_node)
+      && !same_type_p (TREE_TYPE (auto_node), TREE_VEC_ELT (targs, 0)))
+    {
+      error ("inconsistent deduction for %qT: %qT and then %qT",
+	     auto_node, TREE_TYPE (auto_node), TREE_VEC_ELT (targs, 0));
+      return error_mark_node;
+    }
+  TREE_TYPE (auto_node) = TREE_VEC_ELT (targs, 0);
+
   if (processing_template_decl)
     targs = add_to_template_args (current_template_args (), targs);
   return tsubst (type, targs, tf_warning_or_error, NULL_TREE);

gcc/testsuite/ChangeLog

+2009-11-03  Jason Merrill  <jason@redhat.com>
+
+	PR c++/40687
+	* g++.dg/cpp0x/auto3.C: Remove xfail.
+
 2009-11-03  Tobias Burnus  <burnus@net-b.de>
 
 	PR fortran/41907

gcc/testsuite/g++.dg/cpp0x/auto3.C

@@ -7,7 +7,7 @@ auto x;				// { dg-error "auto" }
 
 // If the type deduced for the template parameter U is not the same in each
 // deduction, the program is ill-formed.
-auto i = 42, j = 42.0;		// { dg-error "" "" { xfail *-*-* } }
+auto i = 42, j = 42.0;		// { dg-error "auto" }
 
 // New CWG issue
 auto a[2] = { 1, 2 };		// { dg-error "auto" }