[patch] add LAMBDA_EXPR support to debug_tree()

[Aldy Hernandez]

Hi Jason.

I know LAMBDA_EXPR will never make it to the -fdump-* files, but 
debugging them internally is a pain.  I don't know how you fly blind :).

Would it be ok to add tree dump support for them?  Not pretty, but 
practical...

Aldy
commit 67794c518d439ff2f6a886b19c8e9f0ad32de43b
Author: Aldy Hernandez <al...@redhat.com>
Date:   Fri Mar 6 11:54:31 2015 -0800

        * ptree.c (cxx_print_lambda_node): New.
        (cxx_print_xnode): Handle LAMBDA_EXPR.

diff --git a/gcc/cp/ptree.c b/gcc/cp/ptree.c
index 79c80a3..2d0b584 100644
--- a/gcc/cp/ptree.c
+++ b/gcc/cp/ptree.c
@@ -204,6 +204,34 @@ cxx_print_identifier (FILE *file, tree node, int indent)
 }
 
 void
+cxx_print_lambda_node (FILE *file, tree node, int indent)
+{
+  if (LAMBDA_EXPR_MUTABLE_P (node))
+    fprintf (file, " /mutable");
+  fprintf (file, " default_capture_mode=[");
+  switch (LAMBDA_EXPR_DEFAULT_CAPTURE_MODE (node))
+    {
+    case CPLD_NONE:
+      fprintf (file, "NONE");
+      break;
+    case CPLD_COPY:
+      fprintf (file, "COPY");
+      break;
+    case CPLD_REFERENCE:
+      fprintf (file, "CPLD_REFERENCE");
+      break;
+    default:
+      fprintf (file, "??");
+      break;
+    }
+  fprintf (file, "] ");
+  print_node (file, "capture_list", LAMBDA_EXPR_CAPTURE_LIST (node), indent + 
4);
+  print_node (file, "this_capture", LAMBDA_EXPR_THIS_CAPTURE (node), indent + 
4);
+  print_node (file, "return_type", LAMBDA_EXPR_RETURN_TYPE (node), indent + 4);
+  print_node (file, "closure", LAMBDA_EXPR_CLOSURE (node), indent + 4);
+}
+
+void
 cxx_print_xnode (FILE *file, tree node, int indent)
 {
   switch (TREE_CODE (node))
@@ -243,6 +271,9 @@ cxx_print_xnode (FILE *file, tree node, int indent)
       print_node (file, "pattern", DEFERRED_NOEXCEPT_PATTERN (node), indent+4);
       print_node (file, "args", DEFERRED_NOEXCEPT_ARGS (node), indent+4);
       break;
+    case LAMBDA_EXPR:
+      cxx_print_lambda_node (file, node, indent);
+      break;
     default:
       break;
     }