Reimplement TokenStreams using ropes

src/libsyntax/codemap.rs

@@ -71,6 +71,23 @@ pub fn dummy_spanned<T>(t: T) -> Spanned<T> {
     respan(DUMMY_SP, t)
 }
 
+/// Build a span that covers the two provided spans.
+pub fn combine_spans(sp1: Span, sp2: Span) -> Span {
+    if sp1 == DUMMY_SP && sp2 == DUMMY_SP {
+        DUMMY_SP
+    } else if sp1 == DUMMY_SP {
+        sp2
+    } else if sp2 == DUMMY_SP {
+        sp1
+    } else {
+        Span {
+            lo: if sp1.lo < sp2.lo { sp1.lo } else { sp2.lo },
+            hi: if sp1.hi > sp2.hi { sp1.hi } else { sp2.hi },
+            expn_id: if sp1.expn_id == sp2.expn_id { sp1.expn_id } else { NO_EXPANSION },
+        }
+    }
+}
+
 #[derive(Clone, Hash, Debug)]
 pub struct NameAndSpan {
     /// The format with which the macro was invoked.

src/libsyntax/parse/mod.rs

@@ -237,7 +237,7 @@ pub fn new_parser_from_ts<'a>(sess: &'a ParseSess,
                               cfg: ast::CrateConfig,
                               ts: tokenstream::TokenStream)
                               -> Parser<'a> {
-    tts_to_parser(sess, ts.tts, cfg)
+    tts_to_parser(sess, ts.to_tts(), cfg)
 }