From fdf8543cf61103e56cd86eadd845a65f12eaad54 Mon Sep 17 00:00:00 2001
From: John Clements <clements@racket-lang.org>
Date: Wed, 13 Mar 2013 10:52:45 -0700
Subject: [PATCH] add nonempty encoding for spans

Before this change, encoding an object containing a codemap::span
using the JSON encodeng produced invalid JSON, for instance:
[{"span":,"global":false,"idents":["abc"]}]
Since the decoder for codemap::span's ignores its argument, I
conjecture that this will not damage decoding, and should improve
it for many decoders.
---
 src/libsyntax/codemap.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libsyntax/codemap.rs b/src/libsyntax/codemap.rs
index 0d6ece8ad92f..97719a140a6a 100644
--- a/src/libsyntax/codemap.rs
+++ b/src/libsyntax/codemap.rs
@@ -140,7 +140,7 @@ impl cmp::Eq for span {
 
 impl<S:Encoder> Encodable<S> for span {
     /* Note #1972 -- spans are encoded but not decoded */
-    fn encode(&self, _s: &S) { }
+    fn encode(&self, _s: &S) { _s.emit_nil() }
 }
 
 impl<D:Decoder> Decodable<D> for span {