Re: V4 Lambda templates and implicit function templates.

[Adam Butcher <adam at jessamine dot co dot uk>]

On 11.09.2013 16:25, Jason Merrill wrote:
> On 09/11/2013 10:42 AM, Jason Merrill wrote:
> > Sounds like the problem is that the compiler is trying to 
> > instantiate a
> > function while cp_unevaluated_operand is set.  But that shouldn't be 
> > an
> > issue because push_to_top_level clears cp_unevaluated_operand.  How 
> > does
> > it come to be set when instantiating the local variable?
>
> Ah, I see: it's because instantiate_decl doesn't push_to_top_level
> for function-local templates.  We still need to save/restore
> cp_unevaluated_operand in that case, and let's also do
> c_inhibit_evaluation_warnings.
Great, that fixes it.  Hadn't noticed it didn't happen a namespace 
scope.

Okay for the attached to go to trunk with suitable changelog?

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 22087fb..16e57b5 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -18947,6 +18947,8 @@ instantiate_decl (tree d, int defer_ok,
   tree gen_tmpl;
   bool pattern_defined;
   location_t saved_loc = input_location;
+  int saved_unevaluated_operand = cp_unevaluated_operand;
+  int saved_inhibit_evaluation_warnings = c_inhibit_evaluation_warnings;
   bool external_p;
   tree fn_context;
   bool nested;
@@ -19158,8 +19160,13 @@ instantiate_decl (tree d, int defer_ok,
   nested = (current_function_decl != NULL_TREE);
   if (!fn_context)
     push_to_top_level ();
-  else if (nested)
-    push_function_context ();
+  else
+    {
+      if (nested)
+	push_function_context ();
+      cp_unevaluated_operand = 0;
+      c_inhibit_evaluation_warnings = 0;
+    }
 
   /* Mark D as instantiated so that recursive calls to
      instantiate_decl do not try to instantiate it again.  */
@@ -19283,6 +19290,8 @@ instantiate_decl (tree d, int defer_ok,
 
 out:
   input_location = saved_loc;
+  cp_unevaluated_operand = saved_unevaluated_operand;
+  c_inhibit_evaluation_warnings = saved_inhibit_evaluation_warnings;
   pop_deferring_access_checks ();
   pop_tinst_level ();