re PR c++/57397 (Off-by-one error in diagnostic when calling variadic function template with too few arguments)

/cp
2014-07-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/57397
	* pt.c (unify_arity): Add boolean parameter.
	(unify_too_few_arguments): Likewise.
	(type_unification_real): Diagnose correctly insufficient
	arguments in the presence of trailing variadic parameters;
	deducing multiple trailing packs as empty is fine.

/testsuite
2014-07-30  Paolo Carlini  <paolo.carlini@oracle.com>

	PR c++/57397
	* g++.dg/cpp0x/vt-57397-1.C: New.
	* g++.dg/cpp0x/vt-57397-2.C: Likewise.

From-SVN: r213310

5 files changed, 89 insertions, 12 deletions

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 25d9b8a..f010207 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,12 @@
+2014-07-30  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/57397
+	* pt.c (unify_arity): Add boolean parameter.
+	(unify_too_few_arguments): Likewise.
+	(type_unification_real): Diagnose correctly insufficient
+	arguments in the presence of trailing variadic parameters;
+	deducing multiple trailing packs as empty is fine.
+
 2014-07-30  Jason Merrill  <jason@redhat.com>
 
 	PR c++/61659
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 0eac771..33a8bf4 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -5527,13 +5527,21 @@ unify_method_type_error (bool explain_p, tree arg)
 }
 
 static int
-unify_arity (bool explain_p, int have, int wanted)
+unify_arity (bool explain_p, int have, int wanted, bool least_p = false)
 {
   if (explain_p)
-    inform_n (input_location, wanted,
-	      "  candidate expects %d argument, %d provided",
-	      "  candidate expects %d arguments, %d provided",
-	      wanted, have);
+    {
+      if (least_p)
+	inform_n (input_location, wanted,
+		  "  candidate expects at least %d argument, %d provided",
+		  "  candidate expects at least %d arguments, %d provided",
+		  wanted, have);
+      else
+	inform_n (input_location, wanted,
+		  "  candidate expects %d argument, %d provided",
+		  "  candidate expects %d arguments, %d provided",
+		  wanted, have);
+    }
   return 1;
 }
 
@@ -5544,9 +5552,10 @@ unify_too_many_arguments (bool explain_p, int have, int wanted)
 }
 
 static int
-unify_too_few_arguments (bool explain_p, int have, int wanted)
+unify_too_few_arguments (bool explain_p, int have, int wanted,
+			 bool least_p = false)
 {
-  return unify_arity (explain_p, have, wanted);
+  return unify_arity (explain_p, have, wanted, least_p);
 }
 
 static int
@@ -16627,18 +16636,26 @@ type_unification_real (tree tparms,
      are present, and the parm list isn't variadic.  */
   if (ia < nargs && parms == void_list_node)
     return unify_too_many_arguments (explain_p, nargs, ia);
-  /* Fail if parms are left and they don't have default values.  */
+  /* Fail if parms are left and they don't have default values and
+     they aren't all deduced as empty packs (c++/57397).  This is
+     consistent with sufficient_parms_p.  */
   if (parms && parms != void_list_node
       && TREE_PURPOSE (parms) == NULL_TREE)
     {
       unsigned int count = nargs;
       tree p = parms;
-      while (p && p != void_list_node)
+      bool type_pack_p;
+      do
 	{
-	  count++;
+	  type_pack_p = TREE_CODE (TREE_VALUE (p)) == TYPE_PACK_EXPANSION;
+	  if (!type_pack_p)
+	    count++;
 	  p = TREE_CHAIN (p);
 	}
-      return unify_too_few_arguments (explain_p, ia, count);
+      while (p && p != void_list_node);
+      if (count != nargs)
+	return unify_too_few_arguments (explain_p, ia, count,
+					type_pack_p);
     }
 
   if (!subr)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d0e5f26..629e89e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2014-07-30  Paolo Carlini  <paolo.carlini@oracle.com>
+
+	PR c++/57397
+	* g++.dg/cpp0x/vt-57397-1.C: New.
+	* g++.dg/cpp0x/vt-57397-2.C: Likewise.
+
 2014-07-30  Arnaud Charlet  <charlet@adacore.com>
 
 	* gnat.dg/case_null.adb, gnat.dg/specs/debug1.ads: Adjust tests.
@@ -11,7 +17,6 @@
 
 	* g++.dg/ipa/devirt-34.C: New testcase.
 
->>>>>>> .r213302
 2014-07-28  Richard Biener  <rguenther@suse.de>
 
 	PR rtl-optimization/61801
diff --git a/gcc/testsuite/g++.dg/cpp0x/vt-57397-1.C b/gcc/testsuite/g++.dg/cpp0x/vt-57397-1.C
new file mode 100644
index 0000000..1d9a1e0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/vt-57397-1.C
@@ -0,0 +1,22 @@
+// PR c++/57397
+// { dg-do compile { target c++11 } }
+
+template<class T1, class... Tn>
+void foo(T1, Tn...);
+
+template<class T1, class T2, class... Tn>
+void bar(T1, T2, Tn...);
+
+int main()
+{
+  foo();   // { dg-error "no matching" }
+  // { dg-message "candidate expects at least 1 argument, 0 provided" "" { target *-*-* } 12 }
+  foo(1);
+  foo(1, 2);
+  bar();   // { dg-error "no matching" }
+  // { dg-message "candidate expects at least 2 arguments, 0 provided" "" { target *-*-* } 16 }
+  bar(1);  // { dg-error "no matching" }
+  // { dg-message "candidate expects at least 2 arguments, 1 provided" "" { target *-*-* } 18 }
+  bar(1, 2);
+  bar(1, 2, 3);
+}
diff --git a/gcc/testsuite/g++.dg/cpp0x/vt-57397-2.C b/gcc/testsuite/g++.dg/cpp0x/vt-57397-2.C
new file mode 100644
index 0000000..d217008
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/vt-57397-2.C
@@ -0,0 +1,24 @@
+// PR c++/57397
+// { dg-do compile { target c++11 } }
+
+template<class T1, class... Tn, class... Tm>
+void foo(T1, Tn..., Tm...);
+
+template<class T1, class T2, class... Tn, class... Tm>
+void bar(T1, T2, Tn..., Tm...);
+
+int main()
+{
+  foo();   // { dg-error "no matching" }
+  // { dg-message "candidate expects at least 1 argument, 0 provided" "" { target *-*-* } 12 }
+  foo(1);
+  foo(1, 2);
+  foo(1, 2, 3);
+  bar();   // { dg-error "no matching" }
+  // { dg-message "candidate expects at least 2 arguments, 0 provided" "" { target *-*-* } 17 }
+  bar(1);  // { dg-error "no matching" }
+  // { dg-message "candidate expects at least 2 arguments, 1 provided" "" { target *-*-* } 19 }
+  bar(1, 2);
+  bar(1, 2, 3);
+  bar(1, 2, 3, 4);
+}