From 106f783b33f64cfc364b7aa2e5f57bcd07e9bfb8 Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Fri, 22 Apr 2011 10:51:32 -0700
Subject: rustc: Add a fast path when the types to be unified are exactly equal

---
 src/comp/middle/ty.rs | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'src/comp')

diff --git a/src/comp/middle/ty.rs b/src/comp/middle/ty.rs
index 96479c40..d57b8071 100644
--- a/src/comp/middle/ty.rs
+++ b/src/comp/middle/ty.rs
@@ -1877,6 +1877,9 @@ mod Unify {
         // TODO: occurs check, to make sure we don't loop forever when
         // unifying e.g. 'a and option['a]
 
+        // Fast path.
+        if (eq_ty(expected, actual)) { ret ures_ok(expected); }
+
         alt (actual.struct) {
             // If the RHS is a variable type, then just do the appropriate
             // binding.
-- 
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