Fix highlight duplicated diff

src/renderer/render.rs

@@ -1774,7 +1774,10 @@ fn emit_suggestion_default(
                         // too bad to begin with, so we side-step that issue here.
                         for (i, line) in snippet.lines().enumerate() {
                             let line = normalize_whitespace(line);
-                            let row = row_num - 2 - (newlines - i - 1);
+                            // Going lower than buffer_offset (+ 1) would mean
+                            // overwriting existing content in the buffer
+                            let min_row = buffer_offset + usize::from(!matches_previous_suggestion);
+                            let row = (row_num - 2 - (newlines - i - 1)).max(min_row);
                             // On the first line, we highlight between the start of the part
                             // span, and the end of that line.
                             // On the last line, we highlight between the start of the line, and

tests/color/highlight_duplicated_diff_lines.rs

@@ -0,0 +1,75 @@
+use annotate_snippets::{renderer::DecorStyle, AnnotationKind, Level, Patch, Renderer, Snippet};
+
+use snapbox::{assert_data_eq, file};
+
+#[test]
+fn case() {
+    // https://github.com/rust-lang/rust/blob/4b94758d2ba7d0ef71ccf5fde29ce4bc5d6fe2a4/tests/ui/argument-suggestions/wrong-highlight-span-extra-arguments-147070.rs
+
+    let source = r#"struct Thingie;
+
+impl Thingie {
+    pub(crate) fn new(
+        _a: String,
+        _b: String,
+        _c: String,
+        _d: String,
+        _e: String,
+        _f: String,
+    ) -> Self {
+        unimplemented!()
+    }
+}
+
+fn main() {
+    let foo = Thingie::new(
+        String::from(""),
+        String::from(""),
+        String::from(""),
+        String::from(""),
+        String::from(""),
+        String::from(""),
+        String::from(""),
+    );
+}"#;
+
+    let path = "$DIR/wrong-highlight-span-extra-arguments-147070.rs";
+
+    let report = &[
+        Level::ERROR
+            .primary_title("this function takes 6 arguments but 7 arguments were supplied")
+            .id("E0061")
+            .element(
+                Snippet::source(source)
+                    .path(path)
+                    .annotation(
+                        AnnotationKind::Context
+                            .span(429..445)
+                            .label("unexpected argument #7 of type `String`"),
+                    )
+                    .annotation(AnnotationKind::Primary.span(251..263)),
+            ),
+        Level::NOTE
+            .secondary_title("associated function defined here")
+            .element(
+                Snippet::source(source)
+                    .path(path)
+                    .annotation(AnnotationKind::Primary.span(50..53)),
+            ),
+        Level::HELP
+            .secondary_title("remove the extra argument")
+            .element(
+                Snippet::source(source)
+                    .path(path)
+                    .patch(Patch::new(419..445, "")),
+            ),
+    ];
+
+    let expected_ascii = file!["highlight_duplicated_diff_lines.ascii.term.svg": TermSvg];
+    let renderer = Renderer::styled();
+    assert_data_eq!(renderer.render(report), expected_ascii);
+
+    let expected_unicode = file!["highlight_duplicated_diff_lines.unicode.term.svg": TermSvg];
+    let renderer = renderer.decor_style(DecorStyle::Unicode);
+    assert_data_eq!(renderer.render(report), expected_unicode);
+}

tests/color/main.rs

@@ -9,10 +9,13 @@ mod fold_ann_multiline;
 mod fold_bad_origin_line;
 mod fold_leading;
 mod fold_trailing;
+mod highlight_duplicated_diff_lines;
 mod highlight_source;
 mod issue_9;
 mod multiline_removal_suggestion;
 mod multiple_annotations;
+mod multiple_highlight_duplicated;
+mod multiple_multiline_removal;
 mod primary_title_second_group;
 mod simple;
 mod strip_line;