Display annotation correctly for double width characters across lines

Author: magurotuna

src/display_list/from_snippet.rs

@@ -409,7 +409,11 @@ fn format_body(
                                 });
                             }
                         } else {
-                            let range = (start - line_start_index, start - line_start_index + 1);
+                            let annotation_start_col = char_widths
+                                .iter()
+                                .take(start - line_start_index)
+                                .sum::<usize>();
+                            let range = (annotation_start_col, annotation_start_col + 1);
                             body.insert(
                                 body_idx + 1,
                                 DisplayLine::Source {
@@ -466,7 +470,11 @@ fn format_body(
                             });
                         }
 
-                        let end_mark = (end - line_start_index).saturating_sub(1);
+                        let end_mark = char_widths
+                            .iter()
+                            .take(end - line_start_index)
+                            .sum::<usize>()
+                            .saturating_sub(1);
                         let range = (end_mark - margin_left, (end_mark + 1) - margin_left);
                         body.insert(
                             body_idx + 1,

tests/formatter.rs

@@ -578,3 +578,33 @@ fn test_point_to_double_width_characters() {
 
     assert_eq!(DisplayList::from(snippets).to_string(), expected);
 }
+
+#[test]
+fn test_point_to_double_width_characters_across_lines() {
+    let snippets = Snippet {
+        slices: vec![snippet::Slice {
+            source: "おはよう\nございます",
+            line_start: 1,
+            origin: Some("<current file>"),
+            annotations: vec![snippet::SourceAnnotation {
+                range: (2, 8),
+                label: "Good morning",
+                annotation_type: snippet::AnnotationType::Error,
+            }],
+            fold: false,
+        }],
+        title: None,
+        footer: vec![],
+        opt: Default::default(),
+    };
+
+    let expected = r#" --> <current file>:1:3
+  |
+1 |   おはよう
+  |  _____^
+2 | | ございます
+  | |______^ Good morning
+  |"#;
+
+    assert_eq!(DisplayList::from(snippets).to_string(), expected);
+}