From cb77790aafc1ce69fd150e8009eadefe54557c69 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Thu, 23 Jun 2011 22:13:41 -0400
Subject: [PATCH] re PR c++/35255 ([DR 115] gcc does not do partial ordering on
 overloaded address resolution)

	PR c++/35255
	* pt.c (resolve_overloaded_unification): Fix DR 115 handling.

From-SVN: r175367
---
 gcc/cp/ChangeLog                          |  5 +++++
 gcc/cp/pt.c                               | 11 ++++++++++-
 gcc/testsuite/ChangeLog                   |  6 ++++++
 gcc/testsuite/g++.dg/template/partial10.C | 18 +++++++++++++++++
 gcc/testsuite/g++.dg/template/partial11.C | 24 +++++++++++++++++++++++
 5 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/g++.dg/template/partial10.C
 create mode 100644 gcc/testsuite/g++.dg/template/partial11.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index c7e39be0946..e00b4001c49 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,8 @@
+2011-06-23  Jason Merrill  <jason@redhat.com>
+
+	PR c++/35255
+	* pt.c (resolve_overloaded_unification): Fix DR 115 handling.
+
 2011-06-23  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/44625
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 08ce5afc288..b3dd85f04a7 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -14524,6 +14524,7 @@ resolve_overloaded_unification (tree tparms,
 	 the affected templates before we try to unify, in case the
 	 explicit args will completely resolve the templates in question.  */
 
+      int ok = 0;
       tree expl_subargs = TREE_OPERAND (arg, 1);
       arg = TREE_OPERAND (arg, 0);
 
@@ -14538,7 +14539,7 @@ resolve_overloaded_unification (tree tparms,
 	  ++processing_template_decl;
 	  subargs = get_bindings (fn, DECL_TEMPLATE_RESULT (fn),
 				  expl_subargs, /*check_ret=*/false);
-	  if (subargs)
+	  if (subargs && !any_dependent_template_arguments_p (subargs))
 	    {
 	      elem = tsubst (TREE_TYPE (fn), subargs, tf_none, NULL_TREE);
 	      if (try_one_overload (tparms, targs, tempargs, parm,
@@ -14549,8 +14550,16 @@ resolve_overloaded_unification (tree tparms,
 		  ++good;
 		}
 	    }
+	  else if (subargs)
+	    ++ok;
 	  --processing_template_decl;
 	}
+      /* If no templates (or more than one) are fully resolved by the
+	 explicit arguments, this template-id is a non-deduced context; it
+	 could still be OK if we deduce all template arguments for the
+	 enclosing call through other arguments.  */
+      if (good != 1)
+	good = ok;
     }
   else if (TREE_CODE (arg) != OVERLOAD
 	   && TREE_CODE (arg) != FUNCTION_DECL)
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index c3e0f0e3ba8..bab71b3f32a 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2011-06-23  Jason Merrill  <jason@redhat.com>
+
+	PR c++/35255
+	* g++.dg/template/partial10.C: New.
+	* g++.dg/template/partial11.C: New.
+
 2011-06-23  Jeff Law <law@redhat.com>
 
 	PR middle-end/48770
diff --git a/gcc/testsuite/g++.dg/template/partial10.C b/gcc/testsuite/g++.dg/template/partial10.C
new file mode 100644
index 00000000000..53a48fbac82
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial10.C
@@ -0,0 +1,18 @@
+// PR c++/35255, DR 115
+// { dg-do link }
+
+// 14.8.1: In contexts where deduction is done and fails, or in contexts
+// where deduction is not done, if a template argument list is specified
+// and it, along with any default template arguments, identifies a single
+// function template specialization, then the template-id is an lvalue for
+// the function template specialization.
+
+template <class Fn> void def(Fn fn) {}
+
+template <class T1, class T2> T2 fn(T1, T2);
+template <class T1> int fn(T1) { }
+
+int main()
+{
+  def(fn<int>);
+}
diff --git a/gcc/testsuite/g++.dg/template/partial11.C b/gcc/testsuite/g++.dg/template/partial11.C
new file mode 100644
index 00000000000..b5ceaa883f5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial11.C
@@ -0,0 +1,24 @@
+// DR 115
+
+// 14.8.1: In contexts where deduction is done and fails, or in contexts
+// where deduction is not done, if a template argument list is specified
+// and it, along with any default template arguments, identifies a single
+// function template specialization, then the template-id is an lvalue for
+// the function template specialization.
+
+// Here, deduction is not done to resolve fn<int> because the target type
+// is a template parameter, so we resolve to the second template, and then
+// the call to def fails because we deduce different values of Fn for the
+// two function arguments.
+
+template <class Fn> void def(Fn fn, Fn fn2);
+
+template <class T1, class T2> T2 fn(T1, T2);
+template <class T1> int fn(T1);
+
+int f(int,int);
+
+int main()
+{
+  def(fn<int>,f);		// { dg-error "" }
+}
-- 
2.30.2