PR c++/61806 - missed SFINAE with partial specialization.

	* cp-tree.h (deferring_access_check_sentinel): Add deferring_kind
	parameter to constructor.
	* pt.c (instantiate_class_template_1): Enable access checking
	before call to most_specialized_partial_spec.

From-SVN: r261151

gcc/cp/ChangeLog

 2018-06-04  Jason Merrill  <jason@redhat.com>
 
+	PR c++/61806 - missed SFINAE with partial specialization.
+	* cp-tree.h (deferring_access_check_sentinel): Add deferring_kind
+	parameter to constructor.
+	* pt.c (instantiate_class_template_1): Enable access checking
+	before call to most_specialized_partial_spec.
+
 	PR c++/85765 - SFINAE and non-type default template arg.
 	* pt.c (type_unification_real): Do full semantic processing if
 	substituting a partial args list replaces all template parms.

gcc/cp/cp-tree.h

@@ -6807,9 +6807,9 @@ extern bool perform_or_defer_access_check	(tree, tree, tree,
 
 struct deferring_access_check_sentinel
 {
-  deferring_access_check_sentinel ()
+  deferring_access_check_sentinel (enum deferring_kind kind = dk_deferred)
   {
-    push_deferring_access_checks (dk_deferred);
+    push_deferring_access_checks (kind);
   }
   ~deferring_access_check_sentinel ()
   {

gcc/cp/pt.c

@@ -10850,6 +10850,10 @@ instantiate_class_template_1 (tree type)
   /* Mark the type as in the process of being defined.  */
   TYPE_BEING_DEFINED (type) = 1;
 
+  /* We may be in the middle of deferred access check.  Disable
+     it now.  */
+  deferring_access_check_sentinel acs (dk_no_deferred);
+
   /* Determine what specialization of the original template to
      instantiate.  */
   t = most_specialized_partial_spec (type, tf_warning_or_error);
@@ -10889,10 +10893,6 @@ instantiate_class_template_1 (tree type)
   if (! push_tinst_level (type))
     return type;
 
-  /* We may be in the middle of deferred access check.  Disable
-     it now.  */
-  push_deferring_access_checks (dk_no_deferred);
-
   int saved_unevaluated_operand = cp_unevaluated_operand;
   int saved_inhibit_evaluation_warnings = c_inhibit_evaluation_warnings;
 
@@ -11373,7 +11373,6 @@ instantiate_class_template_1 (tree type)
   maximum_field_alignment = saved_maximum_field_alignment;
   if (!fn_context)
     pop_from_top_level ();
-  pop_deferring_access_checks ();
   pop_tinst_level ();
 
   /* The vtable for a template class can be emitted in any translation

gcc/testsuite/g++.dg/cpp0x/sfinae63.C

+// PR c++/61806
+// { dg-do compile { target c++11 } }
+
+struct true_type 
+{
+  static const bool value = true;
+};
+
+struct false_type 
+{
+  static const bool value = false;
+};
+
+template<class T>
+T&& declval();
+
+template<typename> struct check { typedef void type; };
+
+template<typename T, typename Enable = void>
+struct has_public_f : false_type {};
+
+template<typename T>
+struct has_public_f<
+    T,
+    typename check<
+        decltype(
+            declval<T&>().f()
+        )
+    >::type
+> : true_type {};
+
+
+struct Spub  { public: void f(); };
+struct Spriv { private: void f(); };
+
+static_assert( has_public_f<Spub>::value, "Ouch");
+static_assert(!has_public_f<Spriv>::value, "Ouch");
+
+int main() {}