fix: Allow merging of multiline duplicate annotations

src/renderer/source_map.rs

@@ -213,18 +213,18 @@ impl<'a> SourceMap<'a> {
 
         // Find overlapping multiline annotations, put them at different depths
         multiline_annotations.sort_by_key(|ml| (ml.start.line, usize::MAX - ml.end.line));
-        for ann in multiline_annotations.clone() {
+        for (outer_i, ann) in multiline_annotations.clone().into_iter().enumerate() {
             if ann.kind.is_primary() {
                 primary_spans.push((ann.start, ann.end));
             }
-            for a in &mut multiline_annotations {
+            for (inner_i, a) in &mut multiline_annotations.iter_mut().enumerate() {
                 // Move all other multiline annotations overlapping with this one
                 // one level to the right.
                 if !ann.same_span(a)
                     && num_overlap(ann.start.line, ann.end.line, a.start.line, a.end.line, true)
                 {
                     a.increase_depth();
-                } else if ann.same_span(a) && &ann != a {
+                } else if ann.same_span(a) && outer_i != inner_i {
                     a.overlaps_exactly = true;
                 } else {
                     if primary_spans

tests/formatter.rs

@@ -4235,3 +4235,49 @@ error: showing how tabs are rendered
     let renderer = renderer.decor_style(DecorStyle::Unicode);
     assert_data_eq!(renderer.render(input), expected_unicode);
 }
+
+#[test]
+fn duplicate_annotations() {
+    let source = r#"foobar
+
+            foobar 🚀
+"#;
+    let report = &[
+        Group::with_title(Level::WARNING.primary_title("whatever")).element(
+            Snippet::source(source)
+                .path("whatever")
+                .annotation(AnnotationKind::Primary.span(0..source.len()).label("blah"))
+                .annotation(AnnotationKind::Primary.span(0..source.len()).label("blah")),
+        ),
+    ];
+
+    let expected_ascii = str![[r#"
+warning: whatever
+ --> whatever:1:1
+  |
+1 | / foobar
+2 | |
+3 | |             foobar 🚀
+  | |                      ^
+  | |                      |
+  | |______________________blah
+  |                        blah
+"#]];
+    let renderer = Renderer::plain();
+    assert_data_eq!(renderer.render(report), expected_ascii);
+
+    let expected_unicode = str![[r#"
+warning: whatever
+  ╭▸ whatever:1:1
+  │
+1 │ ┏ foobar
+2 │ ┃
+3 │ ┃             foobar 🚀
+  │ ┃                      ╿
+  │ ┃                      │
+  │ ┗━━━━━━━━━━━━━━━━━━━━━━blah
+  ╰╴                       blah
+"#]];
+    let renderer = renderer.decor_style(DecorStyle::Unicode);
+    assert_data_eq!(renderer.render(report), expected_unicode);
+}