commit ca0a29985403027c3438e5c3c45af35ca1da6bb2
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Nov 17 12:18:57 2017 -0500

            * pt.c (primary_template_specialization_p): Rename from
    
            primary_template_instantiation_p.  Don't check
            DECL_TEMPLATE_INSTANTIATION.
            * call.c, cp-tree.h, decl2.c: Adjust.

diff --git a/gcc/cp/call.c b/gcc/cp/call.c
index d242b07a06b..177c3cc13e3 100644
--- a/gcc/cp/call.c
+++ b/gcc/cp/call.c
@@ -3895,7 +3895,7 @@ build_user_type_conversion_1 (tree totype, tree expr, int flags,
 		= bad_arg_conversion_rejection (NULL_TREE, -2,
 						rettype, totype);
 	    }
-	  else if (primary_template_instantiation_p (cand->fn)
+	  else if (primary_template_specialization_p (cand->fn)
 		   && ics->rank > cr_exact)
 	    {
 	      /* 13.3.3.1.2: If the user-defined conversion is specified by
@@ -6111,7 +6111,7 @@ aligned_deallocation_fn_p (tree t)
   /* A template instance is never a usual deallocation function,
      regardless of its signature.  */
   if (TREE_CODE (t) == TEMPLATE_DECL
-      || primary_template_instantiation_p (t))
+      || primary_template_specialization_p (t))
     return false;
 
   tree a = FUNCTION_ARG_CHAIN (t);
@@ -6136,7 +6136,7 @@ usual_deallocation_fn_p (tree t)
   /* A template instance is never a usual deallocation function,
      regardless of its signature.  */
   if (TREE_CODE (t) == TEMPLATE_DECL
-      || primary_template_instantiation_p (t))
+      || primary_template_specialization_p (t))
     return false;
 
   /* If a class T has a member deallocation function named operator delete
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index 1c19c3d31f8..cb12c835298 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -6556,7 +6556,7 @@ extern void init_template_processing		(void);
 extern void print_template_statistics		(void);
 bool template_template_parameter_p		(const_tree);
 bool template_type_parameter_p                  (const_tree);
-extern bool primary_template_instantiation_p    (const_tree);
+extern bool primary_template_specialization_p   (const_tree);
 extern tree get_primary_template_innermost_parameters	(const_tree);
 extern tree get_template_parms_at_level (tree, int);
 extern tree get_template_innermost_arguments	(const_tree);
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 2b70969999e..53d86fb8722 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -3219,7 +3219,7 @@ get_function_template_decl (const_tree primary_func_tmpl_inst)
 {
   if (! primary_func_tmpl_inst
       || TREE_CODE (primary_func_tmpl_inst) != FUNCTION_DECL
-      || ! primary_template_instantiation_p (primary_func_tmpl_inst))
+      || ! primary_template_specialization_p (primary_func_tmpl_inst))
     return NULL;
 
   return DECL_TEMPLATE_RESULT (DECL_TI_TEMPLATE (primary_func_tmpl_inst));
@@ -3287,21 +3287,23 @@ make_ith_pack_parameter_name (tree name, int i)
 }
 
 /* Return true if T is a primary function, class or alias template
-   instantiation.  */
+   specialization, not including the template pattern.  */
 
 bool
-primary_template_instantiation_p (const_tree t)
+primary_template_specialization_p (const_tree t)
 {
   if (!t)
     return false;
 
-  if (TREE_CODE (t) == FUNCTION_DECL)
-    return DECL_LANG_SPECIFIC (t)
-	   && DECL_TEMPLATE_INSTANTIATION (t)
-	   && PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (t));
+  if (TREE_CODE (t) == FUNCTION_DECL || VAR_P (t))
+    return (DECL_LANG_SPECIFIC (t)
+	    && DECL_USE_TEMPLATE (t)
+	    && DECL_TEMPLATE_INFO (t)
+	    && PRIMARY_TEMPLATE_P (DECL_TI_TEMPLATE (t)));
   else if (CLASS_TYPE_P (t) && !TYPE_DECL_ALIAS_P (TYPE_NAME (t)))
-    return CLASSTYPE_TEMPLATE_INSTANTIATION (t)
-	   && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (t));
+    return (CLASSTYPE_TEMPLATE_INFO (t)
+	    && CLASSTYPE_USE_TEMPLATE (t)
+	    && PRIMARY_TEMPLATE_P (CLASSTYPE_TI_TEMPLATE (t)));
   else if (alias_template_specialization_p (t))
     return true;
   return false;
@@ -3336,7 +3338,7 @@ get_primary_template_innermost_parameters (const_tree t)
   tree parms = NULL, template_info = NULL;
 
   if ((template_info = get_template_info (t))
-      && primary_template_instantiation_p (t))
+      && primary_template_specialization_p (t))
     parms = INNERMOST_TEMPLATE_PARMS
 	(DECL_TEMPLATE_PARMS (TI_TEMPLATE (template_info)));
 
diff --git a/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg2a.C b/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg2a.C
new file mode 100644
index 00000000000..49c1e0557e0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/fntmpdefarg2a.C
@@ -0,0 +1,27 @@
+// PR c++/46831
+// { dg-do compile { target c++11 } }
+// { dg-options "" }
+
+struct B { };
+struct D : B { };
+struct A {
+  template<typename T = void> operator D&(); // { dg-message "template conversion" }
+  operator long();
+};
+
+template <> A::operator D&();
+
+void f(long);
+void f(B&);
+
+struct A2 {
+  template<typename T = void> operator B&();
+};
+
+void f2(const B&);
+
+int main() {
+  f(A());
+  f2(A2());
+  f2(A());			// { dg-error "" }
+}