[PATCH] Support dumping type bindings and 'mutable' qualifier in lambda diagnostics.

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

	* error.c (dump_function_decl): Use standard diagnostic flow to dump a
	lambda diagnostic, albeit without stating the function name or
	duplicating the parameter spec (which is dumped as part of the type).
	Rather than qualifying the diagnostic with 'const' for plain lambdas,
	qualify with 'mutable' if non-const.
---
Okay to commit?
---
 gcc/cp/error.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

diff --git a/gcc/cp/error.c b/gcc/cp/error.c
index c82a0ce..a8ca269 100644
--- a/gcc/cp/error.c
+++ b/gcc/cp/error.c
@@ -1380,14 +1380,7 @@ dump_function_decl (cxx_pretty_printer *pp, tree t, int flags)
   int do_outer_scope = ! (flags & TFF_UNQUALIFIED_NAME);
   tree exceptions;
   vec<tree, va_gc> *typenames = NULL;
-
-  if (DECL_NAME (t) && LAMBDA_FUNCTION_P (t))
-    {
-      /* A lambda's signature is essentially its "type", so defer.  */
-      gcc_assert (LAMBDA_TYPE_P (DECL_CONTEXT (t)));
-      dump_type (pp, DECL_CONTEXT (t), flags);
-      return;
-    }
+  bool lambda_p = false;
 
   flags &= ~(TFF_UNQUALIFIED_NAME | TFF_TEMPLATE_NAME);
   if (TREE_CODE (t) == TEMPLATE_DECL)
@@ -1449,21 +1442,31 @@ dump_function_decl (cxx_pretty_printer *pp, tree t, int flags)
   else if (cname)
     {
       dump_type (pp, cname, flags);
-      pp_cxx_colon_colon (pp);
+      if (LAMBDA_TYPE_P (cname))
+	lambda_p = true;
+      else
+	pp_cxx_colon_colon (pp);
     }
   else
     dump_scope (pp, CP_DECL_CONTEXT (t), flags);
 
-  dump_function_name (pp, t, flags);
+  /* A lambda's signature is essentially its "type", which has already been
+     dumped.  */
+  if (!lambda_p)
+    dump_function_name (pp, t, flags);
 
   if (!(flags & TFF_NO_FUNCTION_ARGUMENTS))
     {
-      dump_parameters (pp, parmtypes, flags);
+      if (!lambda_p)
+	dump_parameters (pp, parmtypes, flags);
 
       if (TREE_CODE (fntype) == METHOD_TYPE)
 	{
 	  pp->padding = pp_before;
-	  pp_cxx_cv_qualifier_seq (pp, class_of_this_parm (fntype));
+	  if (!lambda_p)
+	    pp_cxx_cv_qualifier_seq (pp, class_of_this_parm (fntype));
+	  else if (!(TYPE_QUALS (class_of_this_parm (fntype)) & TYPE_QUAL_CONST))
+	    pp_c_ws_string (pp, "mutable");
 	  dump_ref_qualifier (pp, fntype, flags);
 	}
 
-- 
1.8.4