From 8cd21a315a7eee77fdbfb00e516fb1fe2bfbd4ab Mon Sep 17 00:00:00 2001
From: ickshonpe <david.curthoys@googlemail.com>
Date: Mon, 22 Dec 2025 11:22:12 +0000
Subject: [PATCH] The ASCII fast path assumes that the current word has only
 one attributes span, when it can intersect multiple attribute spans.

This commit adds a check to ensure that all the attribute spans intersecting the word range are compatible before taking the fast path.
Fixes #445
---
 src/shape.rs | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/shape.rs b/src/shape.rs
index 0dbffdd..839630a 100644
--- a/src/shape.rs
+++ b/src/shape.rs
@@ -667,8 +667,14 @@ impl ShapeWord {
         let is_simple_ascii =
             word.is_ascii() && !word.chars().any(|c| c.is_ascii_control() && c != '\t');
 
-        if is_simple_ascii && !word.is_empty() {
-            let _attrs = attrs_list.defaults();
+        if is_simple_ascii && !word.is_empty() && {
+            let attrs_start = attrs_list.get_span(word_range.start);
+            attrs_list.spans_iter().all(|(other_range, other_attrs)| {
+                word_range.end <= other_range.start
+                    || other_range.end <= word_range.start
+                    || attrs_start.compatible(&other_attrs.as_attrs())
+            })
+        } {
             shaping.run(
                 &mut glyphs,
                 font_system,