rust-lang · Muscraft · Jun 25, 2025 · Jun 10, 2025 · Jun 3, 2025
diff --git a/examples/custom_level.svg b/examples/custom_level.svg
diff --git a/src/renderer/mod.rs b/src/renderer/mod.rs
@@ -1874,6 +1874,7 @@ impl Renderer {
                 show_code_change
             {
                 for part in parts {
+                    let snippet = sm.span_to_snippet(part.span.clone()).unwrap_or_default();
                     let (span_start, span_end) = sm.span_to_locations(part.span.clone());
                     let span_start_pos = span_start.display;
                     let span_end_pos = span_end.display;
@@ -1932,13 +1933,86 @@ impl Renderer {
                     }
                     if let DisplaySuggestion::Diff = show_code_change {
                         // Colorize removal with red in diff format.
-                        buffer.set_style_range(
-                            row_num - 2,
-                            (padding as isize + span_start_pos as isize) as usize,
-                            (padding as isize + span_end_pos as isize) as usize,
-                            ElementStyle::Removal,
-                            true,
-                        );
+
+                        // Below, there's some tricky buffer indexing going on. `row_num` at this
+                        // point corresponds to:
+                        //
+                        //    |
+                        // LL | CODE
+                        //    | ++++  <- `row_num`
+                        //
+                        // in the buffer. When we have a diff format output, we end up with
+                        //
+                        //    |
+                        // LL - OLDER   <- row_num - 2
+                        // LL + NEWER
+                        //    |         <- row_num
+                        //
+                        // The `row_num - 2` is to select the buffer line that has the "old version
+                        // of the diff" at that point. When the removal is a single line, `i` is
+                        // `0`, `newlines` is `1` so `(newlines - i - 1)` ends up being `0`, so row
+                        // points at `LL - OLDER`. When the removal corresponds to multiple lines,
+                        // we end up with `newlines > 1` and `i` being `0..newlines - 1`.
+                        //
+       
8000
                 //    |
+                        // LL - OLDER   <- row_num - 2 - (newlines - last_i - 1)
+                        // LL - CODE
+                        // LL - BEING
+                        // LL - REMOVED <- row_num - 2 - (newlines - first_i - 1)
+                        // LL + NEWER
+                        //    |         <- row_num
+
+                        let newlines = snippet.lines().count();
+                        if newlines > 0 && row_num > newlines {
+                            // Account for removals where the part being removed spans multiple
+                            // lines.
+                            // FIXME: We check the number of rows because in some cases, like in
+                            // `tests/ui/lint/invalid-nan-comparison-suggestion.rs`, the rendered
+                            // suggestion will only show the first line of code being replaced. The
+                            // proper way of doing this would be to change the suggestion rendering
+                            // logic to show the whole prior snippet, but the current output is not
+                            // 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);
+                                // 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
+                                // the column of the part span end.
+                                // On all others, we highlight the whole line.
+                                let start = if i == 0 {
+                                    (padding as isize + span_start_pos as isize) as usize
+                                } else {
+                                    padding
+                                };
+                                let end = if i == 0 {
+                                    (padding as isize
+                                        + span_start_pos as isize
+                                        + line.len() as isize)
+                                        as usize
+                                } else if i == newlines - 1 {
+                                    (padding as isize + span_end_pos as isize) as usize
+                                } else {
+                                    (padding as isize + line.len() as isize) as usize
+                                };
+                                buffer.set_style_range(
+                                    row,
+                                    start,
+                                    end,
+                                    ElementStyle::Removal,
+                                    true,
+                                );
+                            }
+                        } else {
+                            // The removed code fits all in one line.
+                            buffer.set_style_range(
+                                row_num - 2,
+                                (padding as isize + span_start_pos as isize) as usize,
+                                (padding as isize + span_end_pos as isize) as usize,
+                                ElementStyle::Removal,
+                                true,
+                            );
+                        }
                     }
 
                     // length of the code after substitution

diff --git a/tests/color/main.rs b/tests/color/main.rs
@@ -9,6 +9,7 @@ mod fold_bad_origin_line;
 mod fold_leading;
 mod fold_trailing;
 mod issue_9;
+mod multiline_removal_suggestion;
 mod multiple_annotations;
 mod simple;
 mod strip_line;

diff --git a/tests/color/multiline_removal_suggestion.rs b/tests/color/multiline_removal_suggestion.rs
@@ -0,0 +1,113 @@
+use annotate_snippets::{AnnotationKind, Group, Level, Origin, Patch, Renderer, Snippet};
+
+use snapbox::{assert_data_eq, file};
+
+#[test]
+fn case() {
+    let source = r#"// Make sure suggestion for removal of a span that covers multiple lines is properly highlighted.
+//@ compile-flags: --error-format=human --color=always
+//@ edition:2018
+//@ only-linux
+// ignore-tidy-tab
+// We use `\t` instead of spaces for indentation to ensure that the highlighting logic properly
+// accounts for replaced characters (like we do for `\t` with `    `). The naïve way of highlighting
+// could be counting chars of the original code, instead of operating on the code as it is being
+// displayed.
+use std::collections::{HashMap, HashSet};
+fn foo() -> Vec<(bool, HashSet<u8>)> {
+	let mut hm = HashMap::<bool, Vec<HashSet<u8>>>::new();
+	hm.into_iter()
+		.map(|(is_true, ts)| {
+			ts.into_iter()
+				.map(|t| {
+					(
+						is_true,
+						t,
+					)
+				}).flatten()
+		})
+		.flatten()
+		.collect()
+}
+fn bar() -> Vec<(bool, HashSet<u8>)> {
+	let mut hm = HashMap::<bool, Vec<HashSet<u8>>>::new();
+	hm.into_iter()
+		.map(|(is_true, ts)| {
+			ts.into_iter()
+				.map(|t| (is_true, t))
+				.flatten()
+		})
+		.flatten()
+		.collect()
+}
+fn baz() -> Vec<(bool, HashSet<u8>)> {
+	let mut hm = HashMap::<bool, Vec<HashSet<u8>>>::new();
+	hm.into_iter()
+		.map(|(is_true, ts)| {
+			ts.into_iter().map(|t| {
+				(is_true, t)
+			}).flatten()
+		})
+		.flatten()
+		.collect()
+}
+fn bay() -> Vec<(bool, HashSet<u8>)> {
+	let mut hm = HashMap::<bool, Vec<HashSet<u8>>>::new();
+	hm.into_iter()
+		.map(|(is_true, ts)| {
+			ts.into_iter()
+				.map(|t| (is_true, t)).flatten()
+		})
+		.flatten()
+		.collect()
+}
+fn main() {}
+"#;
+
+    let input = Level::ERROR
+        .header("`(bool, HashSet<u8>)` is not an iterator")
+        .id("E0277")
+        .group(
+            Group::new()
+                .element(
+                    Snippet::source(source)
+                        .origin("$DIR/multiline-removal-suggestion.rs")
+                        .fold(true)
+                        .annotation(
+                            AnnotationKind::Primary
+                                .span(769..776)
+                                .label("`(bool, HashSet<u8>)` is not an iterator"),
+                        ),
+                )
+                .element(
+                    Level::HELP
+                        .title("the trait `Iterator` is not implemented for `(bool, HashSet<u8>)`"),
+                )
+                .element(
+                    Level::NOTE
+                        .title("required for `(bool, HashSet<u8>)` to implement `IntoIterator`"),
+                ),
+        )
+        .group(
+            Group::new()
+                .element(Level::NOTE.title("required by a bound in `flatten`"))
+                .element(
+                    Origin::new("/rustc/FAKE_PREFIX/library/core/src/iter/traits/iterator.rs")
+                        .line(1556)
+                        .char_column(4),
+                ),
+        )
+        .group(
+            Group::new()
+                .element(Level::HELP.title("consider removing this method call, as the receiver has type `std::vec::IntoIter<HashSet<u8>>` and `std::vec::IntoIter<HashSet<u8>>: Iterator` trivially holds"))
+                .element(
+                    Snippet::source(source)
+                        .origin("$DIR/multiline-removal-suggestion.rs")
+                        .fold(true)
+                        .patch(Patch::new(708..768, "")),
+                ),
+    <
6D40
span class='blob-code-inner blob-code-marker ' data-code-marker="+">        );
+    let expected = file!["multiline_removal_suggestion.term.svg"];
+    let renderer = Renderer::styled();
+    assert_data_eq!(renderer.render(input), expected);
+}
diff --git a/tests/color/multiline_removal_suggestion.term.svg b/tests/color/multiline_removal_suggestion.term.svg