From 6e914c15b7fddfe111c14e39e340741715b954db Mon Sep 17 00:00:00 2001
From: Titus Wormer <tituswormer@gmail.com>
Date: Wed, 23 Apr 2025 16:03:08 +0200
Subject: [PATCH] to_markdown: fix another crash on non-ascii

Related-to: GH-170.
---
 mdast_util_to_markdown/src/state.rs       |  6 ++++++
 mdast_util_to_markdown/tests/paragraph.rs | 13 +++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/mdast_util_to_markdown/src/state.rs b/mdast_util_to_markdown/src/state.rs
index 7a0b5c3..56648ac 100644
--- a/mdast_util_to_markdown/src/state.rs
+++ b/mdast_util_to_markdown/src/state.rs
@@ -535,6 +535,12 @@ impl<'a> State<'a> {
             };
         }
 
+        // Some of the operations above seem to end up right in a utf8 boundary
+        // (see GH-170 for more info).
+        // Move back.
+        while !value.is_char_boundary(start) {
+            start -= 1;
+        }
         result.push_str(&escape_backslashes(&value[start..end], config.after));
 
         result
diff --git a/mdast_util_to_markdown/tests/paragraph.rs b/mdast_util_to_markdown/tests/paragraph.rs
index b04929d..b880103 100644
--- a/mdast_util_to_markdown/tests/paragraph.rs
+++ b/mdast_util_to_markdown/tests/paragraph.rs
@@ -104,4 +104,17 @@ fn paragraph() {
         "a\t&#x9;\n&#x9;\tb\n",
         "should encode spaces around line endings in paragraphs"
     );
+
+    assert_eq!(
+        to(&Node::Paragraph(Paragraph {
+            children: vec![Node::Text(Text {
+                value: String::from("я_я"),
+                position: None
+            })],
+            position: None
+        }))
+        .unwrap(),
+        "я&#x44F;я\n",
+        "should support escaping around non-ascii"
+    );
 }
-- 
2.51.2