C++ PATCH for c++/59349 (ICE with empty lambda init-capture initializer)

[Jason Merrill]

We need to handle getting NULL_TREE for the capture initializer, so that 
we don't crash when trying to do things like look at its type.

Tested x86_64-pc-linux-gnu, applying to trunk.
commit 135f0f322516ce986ed13a214ca9351bd1963749
Author: Jason Merrill <ja...@redhat.com>
Date:   Mon Dec 23 15:05:00 2013 -0500
    	PR c++/59349
    	* parser.c (cp_parser_lambda_introducer): Handle empty init.

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 2a2cbf0..4ef0f05 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -8898,6 +8898,11 @@ cp_parser_lambda_introducer (cp_parser* parser, tree lambda_expr)
 	  capture_init_expr = cp_parser_initializer (parser, &direct,
 						     &non_constant);
 	  explicit_init_p = true;
+	  if (capture_init_expr == NULL_TREE)
+	    {
+	      error ("empty initializer for lambda init-capture");
+	      capture_init_expr = error_mark_node;
+	    }
 	}
       else
 	{
diff --git a/gcc/testsuite/g++.dg/cpp1y/lambda-init7.C b/gcc/testsuite/g++.dg/cpp1y/lambda-init7.C
new file mode 100644
index 0000000..ad152cf
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1y/lambda-init7.C
@@ -0,0 +1,6 @@
+// PR c++/59349
+// { dg-options "-std=c++1y" }
+
+int foo () {
+  [bar()]{};			// { dg-error "empty initializer" }
+}