commit c51bed9b91dd53013feb770278a6e8c466001fa0
Author: Jason Merrill <jason@redhat.com>
Date:   Sat Jul 16 22:20:52 2011 -0400

    	* call.c (template_unification_error_rejection): Define.
    	(add_template_candidate_real): Use it if unification caused errors.
    	(print_z_candidate): Handle it.
    	* pt.c (unify_template_parameter_mismatch): Remove.
    	(unify): Use unify_expression_unequal instead.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index dc8cfe7..0279066 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -666,6 +666,12 @@ template_unification_rejection (tree tmpl, tree explicit_targs, tree targs,
 }
 
 static struct rejection_reason *
+template_unification_error_rejection (void)
+{
+  return alloc_rejection (rr_template_unification);
+}
+
+static struct rejection_reason *
 template_instantiation_rejection (tree tmpl, tree targs)
 {
   struct rejection_reason *r = alloc_rejection (rr_template_instantiation);
@@ -2918,6 +2924,7 @@ add_template_candidate_real (struct z_candidate **candidates, tree tmpl,
   int i;
   tree fn;
   struct rejection_reason *reason = NULL;
+  int errs;
 
   /* We don't do deduction on the in-charge parameter, the VTT
      parameter or 'this'.  */
@@ -2960,6 +2967,7 @@ add_template_candidate_real (struct z_candidate **candidates, tree tmpl,
     }
   gcc_assert (ia == nargs_without_in_chrg);
 
+  errs = errorcount+sorrycount;
   i = fn_type_unification (tmpl, explicit_targs, targs,
 			   args_without_in_chrg,
 			   nargs_without_in_chrg,
@@ -2967,10 +2975,14 @@ add_template_candidate_real (struct z_candidate **candidates, tree tmpl,
 
   if (i != 0)
     {
-      reason = template_unification_rejection (tmpl, explicit_targs,
-					       targs, args_without_in_chrg,
-					       nargs_without_in_chrg,
-					       return_type, strict, flags);
+      /* Don't repeat unification later if it already resulted in errors.  */
+      if (errorcount+sorrycount == errs)
+	reason = template_unification_rejection (tmpl, explicit_targs,
+						 targs, args_without_in_chrg,
+						 nargs_without_in_chrg,
+						 return_type, strict, flags);
+      else
+	reason = template_unification_error_rejection ();
       goto fail;
     }
 
@@ -3253,7 +3265,17 @@ print_z_candidate (const char *msgstr, struct z_candidate *candidate)
 		  r->u.conversion.to_type);
 	  break;
 	case rr_template_unification:
+	  /* We use template_unification_error_rejection if unification caused
+	     actual non-SFINAE errors, in which case we don't need to repeat
+	     them here.  */
+	  if (r->u.template_unification.tmpl == NULL_TREE)
+	    {
+	      inform (loc, "  substitution of deduced template arguments "
+		      "resulted in errors seen above");
+	      break;
+	    }
 	  /* Re-run template unification with diagnostics.  */
+	  inform (loc, "  template argument deduction/substitution failed:");
 	  fn_type_unification (r->u.template_unification.tmpl,
 			       r->u.template_unification.explicit_targs,
 			       r->u.template_unification.targs,
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index b8d25d4..8136a99 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -5464,15 +5464,6 @@ unify_template_deduction_failure (bool explain_p, tree parm, tree arg)
 }
 
 static int
-unify_template_parameter_mismatch (bool explain_p, tree parm, tree tparm)
-{
-  if (explain_p)
-    inform (input_location,
-	    "  template parameter %qT does not match %qD", tparm, parm);
-  return 1;
-}
-
-static int
 unify_template_argument_mismatch (bool explain_p, tree parm, tree arg)
 {
   if (explain_p)
@@ -15920,7 +15911,7 @@ unify (tree tparms, tree targs, tree parm, tree arg, int strict,
 	  int result = !(TREE_CODE (arg) == TREE_CODE (parm)
 			 && cp_tree_equal (parm, arg));
 	  if (result)
-	    unify_template_parameter_mismatch (explain_p, parm, tparm);
+	    unify_expression_unequal (explain_p, parm, arg);
 	  return result;
 	}
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/decltype29.C b/gcc/testsuite/g++.dg/cpp0x/decltype29.C
index 2bb79d0..70fe441 100644
--- a/gcc/testsuite/g++.dg/cpp0x/decltype29.C
+++ b/gcc/testsuite/g++.dg/cpp0x/decltype29.C
@@ -13,7 +13,7 @@ decltype (ft<F> (F()))
 ft() {}				// { dg-error "depth" }
 
 int main() {
-    ft<struct a*, 0>();		// { dg-error "no match" }
+    ft<struct a*, 0>();		// { dg-error "no match|wrong number" }
 }
 
 // { dg-prune-output "note" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/error4.C b/gcc/testsuite/g++.dg/cpp0x/error4.C
index 29a1cdd..064c2f2 100644
--- a/gcc/testsuite/g++.dg/cpp0x/error4.C
+++ b/gcc/testsuite/g++.dg/cpp0x/error4.C
@@ -10,7 +10,7 @@ struct S {
     static U get(const volatile T&);
 
   template<typename U>
-    static decltype(*declval<U>()) get(...);
+    static decltype(*declval<U>()) get(...); // { dg-error "operator*" }
 
   typedef decltype(get<T>(declval<T>())) type; // { dg-error "no match" }
 };
diff --git a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-ice2.C b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-ice2.C
index 120dfaa..8d7d093 100644
--- a/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-ice2.C
+++ b/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-ice2.C
@@ -13,5 +13,5 @@ int main()
 
   run(l); // { dg-error "no match" }
   // { dg-message "candidate" "candidate note" { target *-*-* } 14 }
-  // { dg-error "use of deleted function" "candidate explanation" { target *-*-* } 14 }
+  // { dg-error "use of deleted function" "candidate explanation" { target *-*-* } 5 }
 }
diff --git a/gcc/testsuite/g++.dg/cpp0x/sfinae26.C b/gcc/testsuite/g++.dg/cpp0x/sfinae26.C
index 5b8cdd9..42b48eb 100644
--- a/gcc/testsuite/g++.dg/cpp0x/sfinae26.C
+++ b/gcc/testsuite/g++.dg/cpp0x/sfinae26.C
@@ -32,7 +32,7 @@ struct S {
   template<class... U,
     typename enable_if<and_<is_same<T, U>...>::value>::type*& = enabler
   >
-  S(U...){} // #
+  S(U...){}			// { dg-error "no type named 'type'" }
 };
 
 S<bool> s(0);			// { dg-error "no match" }
diff --git a/gcc/testsuite/g++.dg/cpp0x/variadic105.C b/gcc/testsuite/g++.dg/cpp0x/variadic105.C
index 2729b31..66387b2 100644
--- a/gcc/testsuite/g++.dg/cpp0x/variadic105.C
+++ b/gcc/testsuite/g++.dg/cpp0x/variadic105.C
@@ -21,5 +21,5 @@ struct call_sum {
 int main() {
   // This shouldn't be an error; this is bug 35722.
   reverse<call_sum>(1,2);	// { dg-bogus "no match" "" { xfail *-*-* } }
-  // { dg-message "sorry, unimplemented" "candidate explanation" { target *-*-* } 23 }
+  // { dg-bogus "sorry, unimplemented" "candidate explanation" { xfail *-*-* } 6 }
 }
diff --git a/gcc/testsuite/g++.dg/template/deduce3.C b/gcc/testsuite/g++.dg/template/deduce3.C
index e8a1d4e..c5d6e00 100644
--- a/gcc/testsuite/g++.dg/template/deduce3.C
+++ b/gcc/testsuite/g++.dg/template/deduce3.C
@@ -4,8 +4,8 @@ void f(int, T (*)() = 0);	// { dg-message "note" }
 void g() {
   typedef int A[2];
   f<A>(0); // { dg-error "" }
-  // { dg-message "candidate" "candidate note" { target *-*-* } 6 }
+  // { dg-error "returning an array" "candidate explanation" { target *-*-* } 2 }
   typedef void F();
   f<F>(0); // { dg-error "" }
-  // { dg-message "candidate" "candidate note" { target *-*-* } 9 }
+  // { dg-error "returning a function" "candidate explanation" { target *-*-* } 2 }
 }
diff --git a/gcc/testsuite/g++.dg/template/error45.C b/gcc/testsuite/g++.dg/template/error45.C
index 454acc6..064554d 100644
--- a/gcc/testsuite/g++.dg/template/error45.C
+++ b/gcc/testsuite/g++.dg/template/error45.C
@@ -11,7 +11,7 @@ struct enable_if< true, T >
 
 template < typename T >
 struct enable_if< true, T >::type
-f( T x );
+f( T x );			// { dg-error "not a class type" }
 
 void
 g( void )
diff --git a/gcc/testsuite/g++.dg/template/ptrmem2.C b/gcc/testsuite/g++.dg/template/ptrmem2.C
index 1919047..5f03580 100644
--- a/gcc/testsuite/g++.dg/template/ptrmem2.C
+++ b/gcc/testsuite/g++.dg/template/ptrmem2.C
@@ -7,7 +7,7 @@
 
 struct A {};
 
-template <typename T> T A::* Foo (); // { dg-message "note" }
+template <typename T> T A::* Foo (); // { dg-error "reference" }
 
 void Baz ()
 {
diff --git a/gcc/testsuite/g++.dg/template/sfinae2.C b/gcc/testsuite/g++.dg/template/sfinae2.C
index e39ca6b..c9e1031 100644
--- a/gcc/testsuite/g++.dg/template/sfinae2.C
+++ b/gcc/testsuite/g++.dg/template/sfinae2.C
@@ -8,7 +8,7 @@ template<int T> struct cl {
   const static int value = T;
 };
 
-template<int I> void fn (char (*) [cl<I>::value] = 0 ); // { dg-message "note" }
+template<int I> void fn (char (*) [cl<I>::value] = 0 ); // { dg-error "zero-size array" }
 
 void foo (void)
 {
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/crash60.C b/gcc/testsuite/g++.old-deja/g++.pt/crash60.C
index 1aad621..747af9b 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/crash60.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/crash60.C
@@ -7,7 +7,7 @@
 template< typename SID, class SDR >
 void k( SID sid, SDR* p,
  void (SDR::*)
- ( typename SID::T ) );		// { dg-message "note" }
+ ( typename SID::T ) );		// { dg-error "no type named 'T'" }
 
 struct E { };
 struct S { void f( int ); };
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/unify6.C b/gcc/testsuite/g++.old-deja/g++.pt/unify6.C
index 0e5c034..a6f7674 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/unify6.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/unify6.C
@@ -19,7 +19,7 @@ template<> void fn<int &>() {} // ok, specialize A
 template<> void fn<void ()>() {} // ok, specialize A
 
 // now make sure we moan when we really should
-template<class T> void foo(T const *){} // { dg-message "note" }
+template<class T> void foo(T const *){} // { dg-error "pointer to reference" }
 
 void f()
 {