Auto merge of #12777 - roife:merge-fixes-needless-late-init, r=Alexendoo

fix: merge multiple suggestions into a single multi-span suggestion in `needless_late_init`

See rust-lang/rust-analyzer#17163 (comment).

Currently, the fix for `needless_late_init` would modify multiple parts in the file. However, these modifications are exported as separate suggestions instead of a unified 'multi-part suggestion'.

Consequently, rust-analyzer is unable to perform the fix correctly when applying suggestions automatically, as only one suggestion is processed at a time. This PR addresses this issue by merge all modifications into a single multi-part suggestion.

changelog: [`needless_late_init`]: merge multiple fixes into a single multi-span fix.

Author: bors

clippy_lints/src/needless_late_init.rs

@@ -273,85 +273,62 @@ fn check<'tcx>(
                 msg_span,
                 "unneeded late initialization",
                 |diag| {
-                    diag.tool_only_span_suggestion(
-                        local_stmt.span,
-                        "remove the local",
-                        "",
-                        Applicability::MachineApplicable,
-                    );
-
-                    diag.span_suggestion(
-                        assign.lhs_span,
-                        format!("declare `{binding_name}` here"),
-                        let_snippet,
+                    diag.multipart_suggestion(
+                        format!("move the declaration `{binding_name}` here"),
+                        vec![(local_stmt.span, String::new()), (assign.lhs_span, let_snippet)],
                         Applicability::MachineApplicable,
                     );
                 },
             );
         },
         ExprKind::If(cond, then_expr, Some(else_expr)) if !contains_let(cond) => {
-            let (applicability, suggestions) = assignment_suggestions(cx, binding_id, [then_expr, else_expr])?;
+            let (applicability, mut suggestions) = assignment_suggestions(cx, binding_id, [then_expr, else_expr])?;
 
             span_lint_and_then(
                 cx,
                 NEEDLESS_LATE_INIT,
                 local_stmt.span,
                 "unneeded late initialization",
                 |diag| {
-                    diag.tool_only_span_suggestion(local_stmt.span, "remove the local", String::new(), applicability);
-
-                    diag.span_suggestion_verbose(
-                        usage.stmt.span.shrink_to_lo(),
-                        format!("declare `{binding_name}` here"),
-                        format!("{let_snippet} = "),
-                        applicability,
-                    );
-
-                    diag.multipart_suggestion("remove the assignments from the branches", suggestions, applicability);
+                    suggestions.push((local_stmt.span, String::new()));
+                    suggestions.push((usage.stmt.span.shrink_to_lo(), format!("{let_snippet} = ")));
 
                     if usage.needs_semi {
-                        diag.span_suggestion(
-                            usage.stmt.span.shrink_to_hi(),
-                            "add a semicolon after the `if` expression",
-                            ";",
-                            applicability,
-                        );
+                        suggestions.push((usage.stmt.span.shrink_to_hi(), ";".to_owned()));
                     }
+
+                    diag.multipart_suggestion(
+                        format!(
+                            "move the declaration `{binding_name}` here and remove the assignments from the branches"
+                        ),
+                        suggestions,
+                        applicability,
+                    );
                 },
             );
         },
         ExprKind::Match(_, arms, MatchSource::Normal) => {
-            let (applicability, suggestions) = assignment_suggestions(cx, binding_id, arms.iter().map(|arm| arm.body))?;
+            let (applicability, mut suggestions) =
+                assignment_suggestions(cx, binding_id, arms.iter().map(|arm| arm.body))?;
 
             span_lint_and_then(
                 cx,
                 NEEDLESS_LATE_INIT,
                 local_stmt.span,
                 "unneeded late initialization",
                 |diag| {
-                    diag.tool_only_span_suggestion(local_stmt.span, "remove the local", String::new(), applicability);
+                    suggestions.push((local_stmt.span, String::new()));
+                    suggestions.push((usage.stmt.span.shrink_to_lo(), format!("{let_snippet} = ")));
 
-                    diag.span_suggestion_verbose(
-                        usage.stmt.span.shrink_to_lo(),
-                        format!("declare `{binding_name}` here"),
-                        format!("{let_snippet} = "),
-                        applicability,
-                    );
+                    if usage.needs_semi {
+                        suggestions.push((usage.stmt.span.shrink_to_hi(), ";".to_owned()));
+                    }
 
                     diag.multipart_suggestion(
-                        "remove the assignments from the `match` arms",
+                        format!("move the declaration `{binding_name}` here and remove the assignments from the `match` arms"),
                         suggestions,
                         applicability,
                     );
-
-                    if usage.needs_semi {
-                        diag.span_suggestion(
-                            usage.stmt.span.shrink_to_hi(),
-                            "add a semicolon after the `match` expression",
-                            ";",
-                            applicability,
-                        );
-                    }
                 },
             );
         },