From 4f58db485d82a8d4d4f03f9584ba6de347f704a5 Mon Sep 17 00:00:00 2001
From: Andy Caldwell <andrew.caldwell@metaswitch.com>
Date: Fri, 24 Jul 2015 01:10:25 +0000
Subject: [PATCH] Make ICE an error and use a sensible error message

---
 src/libsyntax/ext/tt/macro_rules.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/libsyntax/ext/tt/macro_rules.rs b/src/libsyntax/ext/tt/macro_rules.rs
index 634572d46940..e29e0ab54d17 100644
--- a/src/libsyntax/ext/tt/macro_rules.rs
+++ b/src/libsyntax/ext/tt/macro_rules.rs
@@ -302,8 +302,8 @@ fn check_lhs_nt_follows(cx: &mut ExtCtxt, lhs: &NamedMatch, sp: Span) {
             tt @ &TtSequence(..) => {
                 check_matcher(cx, Some(tt).into_iter(), &Eof);
             },
-            _ => cx.span_bug(sp, "wrong-structured lhs for follow check (didn't find \
-            a TtDelimited or TtSequence)")
+            _ => cx.span_err(sp, "Invalid macro matcher; matchers must be contained \
+               in balanced delimiters or a repetition indicator")
         },
         _ => cx.span_bug(sp, "wrong-structured lhs for follow check (didn't find a \
            MatchedNonterminal)")