Fix PR c++/69283 (auto deduction fails when ADL is required)

gcc/cp/ChangeLog:

	PR c++/69283
	PR c++/67835
	* decl2.c (mark_used): When given a TEMPLATE_DECL, return after
	setting its TREE_USED flag.

gcc/testsuite/ChangeLog:

	PR c++/69283
	PR c++/67835
	* g++.dg/cpp1y/auto-fn29.C: New test.
	* g++.dg/cpp1y/auto-fn30.C: New test.

From-SVN: r233230

gcc/cp/ChangeLog

+2016-02-08  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR c++/69283
+	PR c++/67835
+	* decl2.c (mark_used): When given a TEMPLATE_DECL, return after
+	setting its TREE_USED flag.
+
 2016-02-08  Jason Merrill  <jason@redhat.com>
 
 	PR c++/69657

gcc/cp/decl2.c

@@ -5068,6 +5068,10 @@ mark_used (tree decl, tsubst_flags_t complain)
 
   /* Set TREE_USED for the benefit of -Wunused.  */
   TREE_USED (decl) = 1;
+
+  if (TREE_CODE (decl) == TEMPLATE_DECL)
+    return true;
+
   if (DECL_CLONED_FUNCTION_P (decl))
     TREE_USED (DECL_CLONED_FUNCTION (decl)) = 1;
 

gcc/testsuite/ChangeLog

+2016-02-08  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR c++/69283
+	PR c++/67835
+	* g++.dg/cpp1y/auto-fn29.C: New test.
+	* g++.dg/cpp1y/auto-fn30.C: New test.
+
 2016-02-08  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/69209

gcc/testsuite/g++.dg/cpp1y/auto-fn29.C

+// PR c++/69283
+// { dg-do compile { target c++14 } }
+
+namespace Ape {
+   struct Type {};
+
+   template <typename T>
+   auto f1(T const& v){
+       return true;
+   }
+
+   template <typename T>
+   auto f2(T const& v){
+       return f2(v); // { dg-error "auto" }
+   }
+}
+
+namespace Baboon {
+   template <typename T>
+   bool f3(T const& v){
+       return f1(v);
+   }
+
+   template <typename T>
+   bool f4(T const& v){
+       f2(v);
+   }
+}
+
+int main(){
+   Ape::Type x;
+   Baboon::f3(x);
+   Baboon::f4(x);
+}

gcc/testsuite/g++.dg/cpp1y/auto-fn30.C

+// PR c++/67835
+// { dg-do compile { target c++14 } }
+
+template<class Tag, class T>
+auto g(Tag tag, T x) {
+ return f(tag, x);
+}
+
+namespace abc {
+struct tag {};
+
+struct A {};
+
+template<class T>
+auto f(tag, T x) { return x; }
+}
+
+int main() {
+ g(abc::tag(), abc::A());
+ return 0;
+}