[Bug c++/84707] [8 Regression] internal compiler error: Segmentation fault (tree_check()/duplicate_decls())

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84707

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
It really seems all we need is 

--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -1410,7 +1410,9 @@ duplicate_decls (tree newdecl, tree olddecl, bool
newdecl_is_friend)
       || TREE_TYPE (olddecl) == error_mark_node)
     return error_mark_node;

-  if (UDLIT_OPER_P (DECL_NAME (newdecl))
+  if (DECL_NAME (newdecl)
+      && DECL_NAME (olddecl)
+      && UDLIT_OPER_P (DECL_NAME (newdecl))
       && UDLIT_OPER_P (DECL_NAME (olddecl)))
     {
       if (TREE_CODE (newdecl) == TEMPLATE_DECL


then we give a nice error:
84707.C:5:1: error: ‘namespace { }’ conflicts with a previous declaration
 namespace {}
 ^~~~~~~~~
84707.C:1:8: note: previous declaration ‘namespace { }’
 inline namespace {
        ^~~~~~~~~