PR c++/88869 - C++17 ICE with CTAD and explicit specialization.

The members of an explicit specialization of a class template don't have the
template parameters of that class template, so we shouldn't try to provide
arguments for them.  Only set outer_args when the class is an instantiation.

	* pt.c (do_class_deduction): Don't include explicit specialization
	args in outer_args.

From-SVN: r269093

gcc/cp/ChangeLog

 2019-02-21  Jason Merrill  <jason@redhat.com>
 
+	PR c++/88869 - C++17 ICE with CTAD and explicit specialization.
+	* pt.c (do_class_deduction): Don't include explicit specialization
+	args in outer_args.
+
 	PR c++/89422 - ICE with -g and lambda in default arg in template.
 	* pt.c (tsubst_function_decl): SET_DECL_FRIEND_CONTEXT sooner.
 

gcc/cp/pt.c

@@ -27224,7 +27224,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init, int flags,
 
   tree outer_args = NULL_TREE;
   if (DECL_CLASS_SCOPE_P (tmpl)
-      && CLASSTYPE_TEMPLATE_INFO (DECL_CONTEXT (tmpl)))
+      && CLASSTYPE_TEMPLATE_INSTANTIATION (DECL_CONTEXT (tmpl)))
     {
       outer_args = CLASSTYPE_TI_ARGS (DECL_CONTEXT (tmpl));
       type = TREE_TYPE (most_general_template (tmpl));

gcc/testsuite/g++.dg/cpp1z/class-deduction63.C

+// PR c++/88869
+// { dg-do compile { target c++17 } }
+
+template <typename> struct B;
+template <> struct B<int> {
+  template <typename T> struct C {
+    T e;
+    C (T f) : e(f) {}
+  };
+  void foo () { C c (42); }
+};