From 4e752651f43a72a1f7dddde0bff932a7ae04960e Mon Sep 17 00:00:00 2001
From: Eduard Burtescu <edy.burt@gmail.com>
Date: Wed, 1 Jan 2014 01:42:24 +0200
Subject: [PATCH] Truncate symbol hashes to 64 bits.

---
 src/librustc/back/link.rs | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/librustc/back/link.rs b/src/librustc/back/link.rs
index 6bd898879d126..cb50e35fd930b 100644
--- a/src/librustc/back/link.rs
+++ b/src/librustc/back/link.rs
@@ -34,6 +34,7 @@ use std::run;
 use std::str;
 use std::io;
 use std::io::fs;
+use extra::hex::ToHex;
 use extra::tempfile::TempDir;
 use syntax::abi;
 use syntax::ast;
@@ -494,8 +495,10 @@ pub fn build_link_meta(sess: Session,
     }
 }
 
-pub fn truncated_hash_result(symbol_hasher: &mut Sha256) -> ~str {
-    symbol_hasher.result_str()
+fn truncated_hash_result(symbol_hasher: &mut Sha256) -> ~str {
+    let output = symbol_hasher.result_bytes();
+    // 64 bits should be enough to avoid collisions.
+    output.slice_to(8).to_hex()
 }