From c788433b15a81935abcb84e9644d04422bf84a48 Mon Sep 17 00:00:00 2001
From: kennytm <kennytm@gmail.com>
Date: Fri, 16 Feb 2018 14:27:45 +0800
Subject: [PATCH] Fix panic when `x.py` is called without any arguments.

---
 src/bootstrap/builder.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index 7345b284dc7..66a1c972462 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -385,8 +385,10 @@ pub fn run(build: &Build) {
             Subcommand::Clean { .. } => panic!(),
         };
 
-        if paths[0] == Path::new("nonexistent/path/to/trigger/cargo/metadata") {
-            return;
+        if let Some(path) = paths.get(0) {
+            if path == Path::new("nonexistent/path/to/trigger/cargo/metadata") {
+                return;
+            }
         }
 
         let builder = Builder {
-- 
2.44.0