c++: Fix checking assert upon invalid class definition [PR116740]

A checking assert triggers upon the following invalid code since
GCC 11:

=== cut here ===
class { a (struct b;
} struct b
=== cut here ===

The problem is that during error recovery, we call
set_identifier_type_value_with_scope for B in the global namespace, and
the checking assert added via r11-7228-g8f93e1b892850b fails.

This patch relaxes that assert to not fail if we've seen a parser error
(it a generalization of another fix done to that checking assert via
r11-7266-g24bf79f1798ad1).

	PR c++/116740

gcc/cp/ChangeLog:

	* name-lookup.cc (set_identifier_type_value_with_scope): Don't
	fail assert with ill-formed input.

gcc/testsuite/ChangeLog:

	* g++.dg/parse/crash80.C: New test.

gcc/cp/name-lookup.cc

@@ -5101,10 +5101,8 @@ set_identifier_type_value_with_scope (tree id, tree decl, cp_binding_level *b)
   if (b->kind == sk_namespace)
     /* At namespace scope we should not see an identifier type value.  */
     gcc_checking_assert (!REAL_IDENTIFIER_TYPE_VALUE (id)
-			 /* We could be pushing a friend underneath a template
-			    parm (ill-formed).  */
-			 || (TEMPLATE_PARM_P
-			     (TYPE_NAME (REAL_IDENTIFIER_TYPE_VALUE (id)))));
+			 /* But we might end up here with ill-formed input.  */
+			 || seen_error ());
   else
     {
       /* Push the current type value, so we can restore it later  */

gcc/testsuite/g++.dg/parse/crash80.C

@@ -0,0 +1,7 @@
+// PR c++/116740
+// { dg-do "compile" }
+
+class K {
+  int a(struct b; // { dg-error "expected '\\)'" }
+};
+struct b {};