From 298a6e66579e5e56fbe2d67f9a4b92f6e1e58ccc Mon Sep 17 00:00:00 2001
From: Tshepang Lekhonkhobe <tshepang@gmail.com>
Date: Mon, 20 Apr 2015 22:55:36 +0200
Subject: [PATCH] lint: explain the non-obvious need for a negative test

---
 src/librustc_lint/builtin.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/librustc_lint/builtin.rs b/src/librustc_lint/builtin.rs
index 7f1a4b659ed..c12ac501c45 100644
--- a/src/librustc_lint/builtin.rs
+++ b/src/librustc_lint/builtin.rs
@@ -923,6 +923,8 @@ impl NonSnakeCase {
                 allow_underscore = match c {
                     '_' if !allow_underscore => return false,
                     '_' => false,
+                    // It would be more obvious to use `c.is_lowercase()`,
+                    // but some characters do not have a lowercase form
                     c if !c.is_uppercase() => true,
                     _ => return false,
                 };