Fix wrapped EOF cursor movement

crates/edit/src/buffer/mod.rs

@@ -3135,7 +3135,8 @@ fn detect_bom(bytes: &[u8]) -> Option<&'static str> {
 
 #[cfg(test)]
 mod tests {
-    use super::{SearchOptions, TextBuffer};
+    use super::{CursorMovement, SearchOptions, TextBuffer};
+    use crate::helpers::Point;
 
     fn buffer_contents(buf: &mut TextBuffer) -> String {
         let mut str = String::new();
@@ -3179,4 +3180,29 @@ mod tests {
 
         assert_eq!(buffer_contents(&mut buf), "ax\nbx\nx\n");
     }
+
+    #[test]
+    fn cursor_left_from_wrapped_eof_stays_on_text() {
+        let mut buf = TextBuffer::new(false).unwrap();
+        buf.set_crlf(false);
+        let text = concat!(
+            "WordWrapBugTest  WordWrapBugTest  WordWrapBugTest  ",
+            "WordWrapBugTestWordWrapBugTest  ",
+            "WordWrapBugTestWordWrapBugTest  ",
+            "WordWrapBugTestWordWrapBugTest  WordWrapBugTest",
+        );
+        buf.write_raw(text.as_bytes());
+        buf.set_margin_enabled(true);
+        buf.set_word_wrap(true);
+        buf.set_width(79);
+        buf.cursor_move_to_logical(Point::MAX);
+
+        assert_eq!(buf.cursor_visual_pos(), Point { x: 47, y: 2 });
+        assert_eq!(buf.visual_line_count(), 3);
+
+        buf.cursor_move_delta(CursorMovement::Grapheme, -1);
+
+        assert_eq!(buf.cursor_visual_pos(), Point { x: 46, y: 2 });
+        assert_eq!(buf.cursor_logical_pos().y, 0);
+    }
 }

crates/edit/src/unicode/measurement.rs

@@ -359,6 +359,10 @@ impl<'doc> MeasurementConfig<'doc> {
                 // Of course we only need to do this if the cursor isn't on a wrap opportunity already.
 
                 // The loop below should not modify the target we already found.
+                let mut chunk_iter = Utf8Chars::new(self.buffer.read_forward(offset), 0);
+                let mut chunk_range = offset..offset + chunk_iter.len();
+                let mut props_next_cluster = ucd_start_of_text_properties();
+                let mut offset_lookahead = offset;
                 let mut visual_pos_x_lookahead = visual_pos_x;
 
                 loop {
@@ -409,7 +413,7 @@ impl<'doc> MeasurementConfig<'doc> {
                         }
                     }
 
-                    if offset_next_cluster == offset {
+                    if offset_next_cluster == offset_lookahead {
                         // No advance and the iterator is empty? End of text reached.
                         if chunk_iter.is_empty() {
                             break;
@@ -443,6 +447,8 @@ impl<'doc> MeasurementConfig<'doc> {
                     } else if !ucd_line_break_joins(props_current_cluster, props_next_cluster) {
                         break;
                     }
+
+                    offset_lookahead = offset_next_cluster;
                 }
             }