c++: array DMI and member fn [PR109666]

Here it turns out I also needed to adjust cfun when stepping out of the
member function to instantiate the DMI.  But instead of adding that tweak,
let's unify with instantiate_body and just push_to_top_level instead of
trying to do the minimum subset of it.  There was no measurable change in
compile time on stdc++.h.

This should also resolve 109506 without yet another tweak.

	PR c++/109666

gcc/cp/ChangeLog:

	* name-lookup.cc (maybe_push_to_top_level)
	(maybe_pop_from_top_level): Split out...
	* pt.cc (instantiate_body): ...from here.
	* init.cc (maybe_instantiate_nsdmi_init): Use them.
	* name-lookup.h: Declare them..

gcc/testsuite/ChangeLog:

	* g++.dg/cpp0x/nsdmi-array2.C: New test.

1 files changed, 2 insertions, 23 deletions

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index 1dd24e3..0b35e10 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -597,32 +597,14 @@ maybe_instantiate_nsdmi_init (tree member, tsubst_flags_t complain)
 	  bool pushed = false;
 	  tree ctx = type_context_for_name_lookup (member);
 
-	  processing_template_decl_sentinel ptds (/*reset*/false);
+	  bool push_to_top = maybe_push_to_top_level (member);
 	  if (!currently_open_class (ctx))
 	    {
-	      if (!LOCAL_CLASS_P (ctx))
-		push_to_top_level ();
-	      else
-		/* push_to_top_level would lose the necessary function context,
-		   just reset processing_template_decl.  */
-		processing_template_decl = 0;
 	      push_nested_class (ctx);
 	      push_deferring_access_checks (dk_no_deferred);
 	      pushed = true;
 	    }
 
-	  /* If we didn't push_to_top_level, still step out of constructor
-	     scope so build_base_path doesn't try to use its __in_chrg.  */
-	  tree cfd = current_function_decl;
-	  auto cbl = current_binding_level;
-	  if (at_function_scope_p ())
-	    {
-	      current_function_decl
-		= decl_function_context (current_function_decl);
-	      while (current_binding_level->kind != sk_class)
-		current_binding_level = current_binding_level->level_chain;
-	    }
-
 	  inject_this_parameter (ctx, TYPE_UNQUALIFIED);
 
 	  start_lambda_scope (member);
@@ -639,15 +621,12 @@ maybe_instantiate_nsdmi_init (tree member, tsubst_flags_t complain)
 	  if (init != error_mark_node)
 	    DECL_INITIAL (member) = init;
 
-	  current_function_decl = cfd;
-	  current_binding_level = cbl;
 	  if (pushed)
 	    {
 	      pop_deferring_access_checks ();
 	      pop_nested_class ();
-	      if (!LOCAL_CLASS_P (ctx))
-		pop_from_top_level ();
 	    }
+	  maybe_pop_from_top_level (push_to_top);
 
 	  input_location = sloc;
 	}