From 46b48ef565a731734522304b95b893ea07ac7ca0 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Tue, 21 Feb 2017 15:50:57 -0500
Subject: [PATCH] PR c++/41727 - ICE with partial spec of partial instantiation

	* pt.c (process_partial_specialization): For now, don't check more
	specialized if there is more than one level of args.

From-SVN: r245642
---
 gcc/cp/ChangeLog                              |  6 +++++
 gcc/cp/pt.c                                   |  3 +++
 .../g++.dg/template/partial-specialization5.C | 22 +++++++++++++++++++
 3 files changed, 31 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/template/partial-specialization5.C

diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index 90272d2638e..13d7d33b8c3 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,9 @@
+2017-02-21  Jason Merrill  <jason@redhat.com>
+
+	PR c++/41727 - ICE with partial spec of partial instantiation
+	* pt.c (process_partial_specialization): For now, don't check more
+	specialized if there is more than one level of args.
+
 2017-02-21  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/79535
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index c29e691b44c..38a01e168a7 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -4619,6 +4619,9 @@ process_partial_specialization (tree decl)
 
   /* If we aren't in a dependent class, we can actually try deduction.  */
   else if (tpd.level == 1
+	   /* FIXME we should be able to handle a partial specialization of a
+	      partial instantiation, but currently we can't (c++/41727).  */
+	   && TMPL_ARGS_DEPTH (specargs) == 1
 	   && !get_partial_spec_bindings (maintmpl, maintmpl, specargs))
     {
       if (permerror (input_location, "partial specialization %qD is not "
diff --git a/gcc/testsuite/g++.dg/template/partial-specialization5.C b/gcc/testsuite/g++.dg/template/partial-specialization5.C
new file mode 100644
index 00000000000..7a8db5a9661
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/partial-specialization5.C
@@ -0,0 +1,22 @@
+// PR c++/41727
+
+struct tag0;
+
+template < class Tag > struct outer
+{
+  template < typename Arg0, typename Arg1 > struct inner;
+};
+
+template < int Value > struct value_wrap { };
+
+template </* class Tag */>
+template < typename Arg0, int Arg1 >
+struct outer <tag0 >::inner < Arg0, value_wrap < Arg1 > >
+{
+  typedef Arg0 type;
+};
+
+typedef outer < tag0 >
+::inner < tag0, value_wrap < 999 > >
+::type				// { dg-bogus "incomplete" "" { xfail *-*-* } }
+  outer_inner_type;
-- 
2.30.2