From d061ab6c8e7d40b5b83c324282b0d8a7da6ada0a Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Thu, 30 Jul 2020 15:40:15 +0200
Subject: [PATCH] Code shuffle resiliently

---
 crates/rust-analyzer/src/cli/analysis_stats.rs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/crates/rust-analyzer/src/cli/analysis_stats.rs b/crates/rust-analyzer/src/cli/analysis_stats.rs
index 187a0ebe632..a270eb481c0 100644
--- a/crates/rust-analyzer/src/cli/analysis_stats.rs
+++ b/crates/rust-analyzer/src/cli/analysis_stats.rs
@@ -309,8 +309,13 @@ pub fn analysis_stats(
 }
 
 fn shuffle<T>(rng: &mut Rand32, slice: &mut [T]) {
-    for i in (1..slice.len()).rev() {
-        let idx = rng.rand_range(0..i as u32) as usize;
-        slice.swap(idx, i)
+    for i in 0..slice.len() {
+        randomize_first(rng, &mut slice[i..]);
+    }
+
+    fn randomize_first<T>(rng: &mut Rand32, slice: &mut [T]) {
+        assert!(!slice.is_empty());
+        let idx = rng.rand_range(0..slice.len() as u32) as usize;
+        slice.swap(0, idx);
     }
 }