Rollup merge of rust-lang#146121 - Muscraft:filter-suggestion-parts, r=petrochenkov

fix: Filter suggestion parts that match existing code

While testing my changes to make `rustc` use `annotate-snippets`, I encountered a new `clippy` test failure stemming from [two](https://github.com/rust-lang/rust/pull/145273/files#diff-6e8403e31463539666afbc00479cb416dc767a518f562b6e2960630953ee7da2R275-R278) [suggestion](https://github.com/rust-lang/rust/pull/145273/files#diff-6e8403e31463539666afbc00479cb416dc767a518f562b6e2960630953ee7da2R289-R292) output changes in rust-lang#145273. The new output in these two cases feels like a regression as it is not as clear as the old output, and adds unnecessary information.

Before rust-lang#145273 (`Diff` style)
![before](https://github.com/user-attachments/assets/36f33635-cbce-45f1-823d-0cbe6f0cfe46)

After rust-lang#145273 ("multi-line" style)
![after](https://github.com/user-attachments/assets/d4cb00b8-5a42-436e-9329-db84347138f0)

The reason for the change was that a new suggestion part (which matches existing code) was added on a different line than the existing parts, causing the suggestion style to change from `Diff` to "multi-line". Since this new part matches existing code, no code changes show up in the output for it, but it still makes the suggestion style "multi-line" when it doesn't need to be.

To get the old output back, I made it so that suggestion parts that perfectly match existing code get filtered out.

Author: tgross35

compiler/rustc_errors/src/lib.rs

@@ -378,6 +378,11 @@ impl CodeSuggestion {
             })
             .cloned()
             .filter_map(|mut substitution| {
+                // Account for cases where we are suggesting the same code that's already
+                // there. This shouldn't happen often, but in some cases for multipart
+                // suggestions it's much easier to handle it here than in the origin.
+                substitution.parts.retain(|p| is_different(sm, &p.snippet, p.span));
+
                 // Assumption: all spans are in the same file, and all spans
                 // are disjoint. Sort in ascending order.
                 substitution.parts.sort_by_key(|part| part.span.lo());
@@ -470,16 +475,12 @@ impl CodeSuggestion {
                             _ => 1,
                         })
                         .sum();
-                    if !is_different(sm, &part.snippet, part.span) {
-                        // Account for cases where we are suggesting the same code that's already
-                        // there. This shouldn't happen often, but in some cases for multipart
-                        // suggestions it's much easier to handle it here than in the origin.
-                    } else {
-                        line_highlight.push(SubstitutionHighlight {
-                            start: (cur_lo.col.0 as isize + acc) as usize,
-                            end: (cur_lo.col.0 as isize + acc + len) as usize,
-                        });
-                    }
+
+                    line_highlight.push(SubstitutionHighlight {
+                        start: (cur_lo.col.0 as isize + acc) as usize,
+                        end: (cur_lo.col.0 as isize + acc + len) as usize,
+                    });
+
                     buf.push_str(&part.snippet);
                     let cur_hi = sm.lookup_char_pos(part.span.hi());
                     // Account for the difference between the width of the current code and the

src/tools/clippy/tests/ui/bool_assert_comparison.stderr

@@ -272,10 +272,8 @@ LL |     assert_eq!(a!(), true);
    |
 help: replace it with `assert!(..)`
    |
-LL |         true
-...
-LL |
-LL ~     assert!(a!());
+LL -     assert_eq!(a!(), true);
+LL +     assert!(a!());
    |
 
 error: used `assert_eq!` with a literal bool
@@ -286,10 +284,8 @@ LL |     assert_eq!(true, b!());
    |
 help: replace it with `assert!(..)`
    |
-LL |         true
-...
-LL |
-LL ~     assert!(b!());
+LL -     assert_eq!(true, b!());
+LL +     assert!(b!());
    |
 
 error: used `debug_assert_eq!` with a literal bool