[Bug c++/67337] [4.9/5/6 Regression] Segmentation fault on a template class

[trippels at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67337

--- Comment #2 from Markus Trippelsdorf <trippels at gcc dot gnu.org> ---
Testing obvious fix:

diff --git a/gcc/cp/mangle.c b/gcc/cp/mangle.c
index 342cb93e68b3..a9993f40b94d 100644
--- a/gcc/cp/mangle.c
+++ b/gcc/cp/mangle.c
@@ -1149,7 +1149,7 @@ write_template_prefix (const tree node)
      So, for the example above, `Outer<int>::Inner' is represented as a
      substitution candidate by a TREE_LIST whose purpose is `Outer<int>'
      and whose value is `Outer<T>::Inner<U>'.  */
-  if (TYPE_P (context))
+  if (context && TYPE_P (context))
     substitution = build_tree_list (context, templ);
   else
     substitution = templ;