From 5c09e09c10bbb5f0715d8e95449df1a03b1af327 Mon Sep 17 00:00:00 2001
From: Elijah Potter <me@elijahpotter.dev>
Date: Thu, 11 Dec 2025 12:29:36 -0700
Subject: [PATCH] fix(core): seal trait

---
 harper-core/src/char_string.rs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/harper-core/src/char_string.rs b/harper-core/src/char_string.rs
index b7e8b192..d3e956c0 100644
--- a/harper-core/src/char_string.rs
+++ b/harper-core/src/char_string.rs
@@ -7,8 +7,14 @@ use smallvec::SmallVec;
 /// Most English words are fewer than 12 characters.
 pub type CharString = SmallVec<[char; 16]>;
 
+mod private {
+    pub trait Sealed {}
+
+    impl Sealed for [char] {}
+}
+
 /// Extensions to character sequences that make them easier to wrangle.
-pub trait CharStringExt {
+pub trait CharStringExt: private::Sealed {
     /// Convert all characters to lowercase, returning a new owned vector if any changes were made.
     fn to_lower(&'_ self) -> Cow<'_, [char]>;