commit b7eabaa932f7f309630fc7163e64d61b1aba17c8
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Nov 9 16:39:25 2011 -0500

    	PR c++/50972
    	* pt.c (maybe_instantiate_noexcept): Check the return value of
    	push_tinst_level.

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 71a98b0..55eba5a 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -18166,17 +18166,22 @@ maybe_instantiate_noexcept (tree fn)
 
   if (TREE_CODE (noex) == DEFERRED_NOEXCEPT)
     {
-      push_tinst_level (fn);
-      push_access_scope (fn);
-      input_location = DECL_SOURCE_LOCATION (fn);
-      noex = tsubst_copy_and_build (DEFERRED_NOEXCEPT_PATTERN (noex),
-				    DEFERRED_NOEXCEPT_ARGS (noex),
-				    tf_warning_or_error, fn, /*function_p=*/false,
-				    /*integral_constant_expression_p=*/true);
-      pop_access_scope (fn);
-      pop_tinst_level ();
-      spec = build_noexcept_spec (noex, tf_warning_or_error);
-      if (spec == error_mark_node)
+      if (push_tinst_level (fn))
+	{
+	  push_access_scope (fn);
+	  input_location = DECL_SOURCE_LOCATION (fn);
+	  noex = tsubst_copy_and_build (DEFERRED_NOEXCEPT_PATTERN (noex),
+					DEFERRED_NOEXCEPT_ARGS (noex),
+					tf_warning_or_error, fn,
+					/*function_p=*/false,
+					/*integral_constant_expression_p=*/true);
+	  pop_access_scope (fn);
+	  pop_tinst_level ();
+	  spec = build_noexcept_spec (noex, tf_warning_or_error);
+	  if (spec == error_mark_node)
+	    spec = noexcept_false_spec;
+	}
+      else
 	spec = noexcept_false_spec;
     }
   else
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept16.C b/gcc/testsuite/g++.dg/cpp0x/noexcept16.C
new file mode 100644
index 0000000..10e0be9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept16.C
@@ -0,0 +1,130 @@
+// PR c++/50972
+// { dg-do compile { target c++11 } }
+// Ignore all errors, we're just testing that this doesn't ICE
+// { dg-prune-output "error" }
+
+namespace std
+typedef long unsigned int size_t;
+template<typename...>
+struct __and_;
+template<typename _Tp>
+struct is_nothrow_move_constructible
+{
+};
+template<typename _Tp>
+struct is_nothrow_move_assignable
+struct __add_rvalue_reference_helper<_Tp, true>
+{ typedef _Tp&& type; };
+template<typename _Tp>
+struct add_rvalue_reference
+  : public __add_rvalue_reference_helper<_Tp>
+{
+};
+template<typename _Tp>
+inline typename add_rvalue_reference<_Tp>::type
+declval() noexcept
+{
+}
+}
+namespace __gnu_cxx __attribute__ ((__visibility__ ("default")))
+template<typename _Tp>
+class new_allocator
+{
+};
+}
+namespace std __attribute__ ((__visibility__ ("default")))
+class allocator: public __gnu_cxx::new_allocator<_Tp>
+{
+  template<typename _Tp1>
+  struct rebind
+  { typedef allocator<_Tp1> other; };
+};
+}
+namespace std __attribute__ ((__visibility__ ("default")))
+template<typename _Alloc, typename _Tp>
+struct __alloctr_rebind<_Alloc, _Tp, true>
+{
+  typedef typename _Alloc::template rebind<_Tp>::other __type;
+};
+template<typename _Alloc>
+struct allocator_traits
+{
+  template<typename _Tp>
+  struct __rebind_alloc
+  {
+    typedef typename __alloctr_rebind<_Alloc, _Tp>::__type __type;
+  };
+}
+  }
+namespace __gnu_cxx __attribute__ ((__visibility__ ("default")))
+template<typename _Alloc>
+struct __alloc_traits
+{
+  typedef std::allocator_traits<_Alloc> _Base_type;
+  static constexpr bool _S_nothrow_swap()
+  {
+    return !_S_propagate_on_swap()
+      || noexcept(swap(std::declval<_Alloc&>(), std::declval<_Alloc&>()));
+  }
+  template<typename _Tp>
+  struct rebind
+  { typedef typename _Base_type::template __rebind_alloc<_Tp>::__type other; };
+};
+}
+namespace std __attribute__ ((__visibility__ ("default")))
+template<typename _Tp, typename _Alloc>
+struct _Vector_base
+{
+  typedef typename __gnu_cxx::__alloc_traits<_Alloc>::template
+  rebind<_Tp>::other _Tp_alloc_type;
+};
+template<typename _Tp, typename _Alloc = std::allocator<_Tp> >
+class vector : protected _Vector_base<_Tp, _Alloc>
+{
+  typedef _Vector_base<_Tp, _Alloc> _Base;
+  typedef typename _Base::_Tp_alloc_type _Tp_alloc_type;
+  typedef __gnu_cxx::__alloc_traits<_Tp_alloc_type> _Alloc_traits;
+  swap(vector& __x)
+  noexcept(_Alloc_traits::_S_nothrow_swap());
+};
+}
+namespace lexertl
+namespace detail
+}
+namespace detail
+template<typename id_type>
+struct basic_internals
+{
+  typedef std::vector<id_type> id_type_vector;
+};
+};
+template<typename char_type, typename id_type = std::size_t>
+class basic_state_machine
+{
+  typedef detail::basic_internals<id_type> internals;
+  void minimise ()
+  {
+    minimise_dfa (dfa_alphabet_, *dfa_, size_);
+  }
+  typedef typename internals::id_type_vector id_type_vector;
+  void minimise_dfa (const id_type dfa_alphabet_,
+		     id_type_vector &dfa_, std::size_t size_)
+  {
+    id_type_vector new_dfa_ (front_, front_ + dfa_alphabet_);
+    dfa_.swap (new_dfa_);
+  }
+}
+  }
+namespace std __attribute__ ((__visibility__ ("default")))
+template<typename _Tp>
+void
+swap(_Tp&, _Tp&)
+  noexcept(__and_<is_nothrow_move_constructible<_Tp>,
+	   is_nothrow_move_assignable<_Tp>>::value)
+  ;
+typedef lexertl::basic_state_machine<char32_t> lexstate;
+lexstate m_state_machine;
+GenerateLexer()
+{
+  m_state_machine.minimise();
+}
