From 7ccc97e5b4fb6a9a3fb76b806df4e22b9401a47c Mon Sep 17 00:00:00 2001
From: Corey Richardson <corey@octayn.net>
Date: Wed, 22 May 2013 14:21:09 -0400
Subject: [PATCH 1/2] Fix ICE in macros

---
 src/libsyntax/ext/tt/transcribe.rs | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/libsyntax/ext/tt/transcribe.rs b/src/libsyntax/ext/tt/transcribe.rs
index d806801b7d172..b13dc3f3c0fe7 100644
--- a/src/libsyntax/ext/tt/transcribe.rs
+++ b/src/libsyntax/ext/tt/transcribe.rs
@@ -118,10 +118,13 @@ fn lookup_cur_matched_by_matched(r: &mut TtReader,
 }
 
 fn lookup_cur_matched(r: &mut TtReader, name: ident) -> @named_match {
-    // FIXME (#3850): this looks a bit silly with an extra scope.
-    let start;
-    { start = *r.interpolations.get(&name); }
-    return lookup_cur_matched_by_matched(r, start);
+    match r.interpolations.find_copy(&name) {
+        Some(s) => lookup_cur_matched_by_matched(r, s),
+        None => {
+            r.sp_diag.span_fatal(r.cur_span, fmt!("unknown macro variable `%s`",
+                                                  *r.interner.get(name)));
+        }
+    }
 }
 enum lis {
     lis_unconstrained, lis_constraint(uint, ident), lis_contradiction(~str)

From 5118d2f84a4c4a8bf00d7fb9e06609877bf821e7 Mon Sep 17 00:00:00 2001
From: Corey Richardson <corey@octayn.net>
Date: Wed, 22 May 2013 16:07:02 -0400
Subject: [PATCH 2/2] Add test

---
 src/test/compile-fail/issue-6596.rs | 9 +++++++++
 1 file changed, 9 insertions(+)
 create mode 100644 src/test/compile-fail/issue-6596.rs

diff --git a/src/test/compile-fail/issue-6596.rs b/src/test/compile-fail/issue-6596.rs
new file mode 100644
index 0000000000000..3c952dbc59087
--- /dev/null
+++ b/src/test/compile-fail/issue-6596.rs
@@ -0,0 +1,9 @@
+macro_rules! e( //~ ERROR unknown macro variable `nonexistent`
+    ($inp:ident) => (
+        $nonexistent
+    );
+)
+
+fn main() {
+    e!(foo);
+}