From 9b489f6fff4aa07bea2db9457ece5f77c211e016 Mon Sep 17 00:00:00 2001
From: Ben Blum <bblum@andrew.cmu.edu>
Date: Tue, 21 Aug 2012 21:03:47 -0400
Subject: [PATCH] Don't refute "()" in let-bindings (fixes #3104).

---
 src/rustc/middle/check_alt.rs         | 1 +
 src/test/run-pass/irrefutable-unit.rs | 3 +++
 2 files changed, 4 insertions(+)
 create mode 100644 src/test/run-pass/irrefutable-unit.rs

diff --git a/src/rustc/middle/check_alt.rs b/src/rustc/middle/check_alt.rs
index 66216b523cb4..07351f49bea5 100644
--- a/src/rustc/middle/check_alt.rs
+++ b/src/rustc/middle/check_alt.rs
@@ -420,6 +420,7 @@ fn is_refutable(tcx: ty::ctxt, pat: @pat) -> bool {
         is_refutable(tcx, sub)
       }
       pat_wild | pat_ident(_, _, none) => { false }
+      pat_lit(@{node: expr_lit(@{node: lit_nil, _}), _}) => { false } // "()"
       pat_lit(_) | pat_range(_, _) => { true }
       pat_rec(fields, _) => {
         for fields.each |it| {
diff --git a/src/test/run-pass/irrefutable-unit.rs b/src/test/run-pass/irrefutable-unit.rs
new file mode 100644
index 000000000000..15b439131178
--- /dev/null
+++ b/src/test/run-pass/irrefutable-unit.rs
@@ -0,0 +1,3 @@
+fn main() {
+    let ((),()) = ((),());
+}