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 https://github.com/rust-lang/rust-analyzer/issues/17163#issuecomment-2097840922.

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.

2 files changed, 104 insertions, 142 deletions

diff --git a/clippy_lints/src/needless_late_init.rs b/clippy_lints/src/needless_late_init.rs
index 6605d1fa51a..5a0ae1a4d6d 100644
--- a/clippy_lints/src/needless_late_init.rs
+++ b/clippy_lints/src/needless_late_init.rs
@@ -273,24 +273,16 @@ 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,
@@ -298,30 +290,26 @@ fn check<'tcx>(
                 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,
@@ -329,29 +317,18 @@ fn check<'tcx>(
                 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,
-                        );
-                    }
                 },
             );
         },
diff --git a/tests/ui/needless_late_init.stderr b/tests/ui/needless_late_init.stderr
index 1695784030d..ce64861fa40 100644
--- a/tests/ui/needless_late_init.stderr
+++ b/tests/ui/needless_late_init.stderr
@@ -8,10 +8,11 @@ LL |     a = "zero";
    |
    = note: `-D clippy::needless-late-init` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::needless_late_init)]`
-help: declare `a` here
+help: move the declaration `a` here
+   |
+LL ~     
+LL ~     let a = "zero";
    |
-LL |     let a = "zero";
-   |     ~~~~~
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:30:5
@@ -22,10 +23,12 @@ LL |     let c;
 LL |     b = 1;
    |     ^^^^^ initialised here
    |
-help: declare `b` here
+help: move the declaration `b` here
+   |
+LL ~     
+LL |     let c;
+LL ~     let b = 1;
    |
-LL |     let b = 1;
-   |     ~~~~~
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:31:5
@@ -36,10 +39,12 @@ LL |     b = 1;
 LL |     c = 2;
    |     ^^^^^ initialised here
    |
-help: declare `c` here
+help: move the declaration `c` here
+   |
+LL ~     
+LL |     b = 1;
+LL ~     let c = 2;
    |
-LL |     let c = 2;
-   |     ~~~~~
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:35:5
@@ -49,10 +54,11 @@ LL |     let d: usize;
 LL |     d = 1;
    |     ^^^^^ initialised here
    |
-help: declare `d` here
+help: move the declaration `d` here
+   |
+LL ~     
+LL ~     let d: usize = 1;
    |
-LL |     let d: usize = 1;
-   |     ~~~~~~~~~~~~
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:38:5
@@ -62,10 +68,11 @@ LL |     let e;
 LL |     e = format!("{}", d);
    |     ^^^^^^^^^^^^^^^^^^^^ initialised here
    |
-help: declare `e` here
+help: move the declaration `e` here
+   |
+LL ~     
+LL ~     let e = format!("{}", d);
    |
-LL |     let e = format!("{}", d);
-   |     ~~~~~
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:43:5
@@ -73,20 +80,17 @@ error: unneeded late initialization
 LL |     let a;
    |     ^^^^^^
    |
-help: declare `a` here
-   |
-LL |     let a = match n {
-   |     +++++++
-help: remove the assignments from the `match` arms
+help: move the declaration `a` here and remove the assignments from the `match` arms
    |
+LL ~     
+LL |     let n = 1;
+LL ~     let a = match n {
 LL ~         1 => "one",
 LL |         _ => {
 LL ~             "two"
+LL |         },
+LL ~     };
    |
-help: add a semicolon after the `match` expression
-   |
-LL |     };
-   |      +
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:52:5
@@ -94,20 +98,15 @@ error: unneeded late initialization
 LL |     let b;
    |     ^^^^^^
    |
-help: declare `b` here
-   |
-LL |     let b = if n == 3 {
-   |     +++++++
-help: remove the assignments from the branches
+help: move the declaration `b` here and remove the assignments from the branches
    |
+LL ~     
+LL ~     let b = if n == 3 {
 LL ~         "four"
 LL |     } else {
 LL ~         "five"
+LL ~     };
    |
-help: add a semicolon after the `if` expression
-   |
-LL |     };
-   |      +
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:59:5
@@ -115,20 +114,16 @@ error: unneeded late initialization
 LL |     let d;
    |     ^^^^^^
    |
-help: declare `d` here
-   |
-LL |     let d = if true {
-   |     +++++++
-help: remove the assignments from the branches
+help: move the declaration `d` here and remove the assignments from the branches
    |
+LL ~     
+LL ~     let d = if true {
+LL |         let temp = 5;
 LL ~         temp
 LL |     } else {
 LL ~         15
+LL ~     };
    |
-help: add a semicolon after the `if` expression
-   |
-LL |     };
-   |      +
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:67:5
@@ -136,20 +131,15 @@ error: unneeded late initialization
 LL |     let e;
    |     ^^^^^^
    |
-help: declare `e` here
-   |
-LL |     let e = if true {
-   |     +++++++
-help: remove the assignments from the branches
+help: move the declaration `e` here and remove the assignments from the branches
    |
+LL ~     
+LL ~     let e = if true {
 LL ~         format!("{} {}", a, b)
 LL |     } else {
 LL ~         format!("{}", n)
+LL ~     };
    |
-help: add a semicolon after the `if` expression
-   |
-LL |     };
-   |      +
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:74:5
@@ -157,14 +147,11 @@ error: unneeded late initialization
 LL |     let f;
    |     ^^^^^^
    |
-help: declare `f` here
-   |
-LL |     let f = match 1 {
-   |     +++++++
-help: remove the assignments from the `match` arms
+help: move the declaration `f` here and remove the assignments from the `match` arms
    |
-LL -         1 => f = "three",
-LL +         1 => "three",
+LL ~     
+LL ~     let f = match 1 {
+LL ~         1 => "three",
    |
 
 error: unneeded late initialization
@@ -173,19 +160,15 @@ error: unneeded late initialization
 LL |     let g: usize;
    |     ^^^^^^^^^^^^^
    |
-help: declare `g` here
-   |
-LL |     let g: usize = if true {
-   |     ++++++++++++++
-help: remove the assignments from the branches
-   |
-LL -         g = 5;
-LL +         5
+help: move the declaration `g` here and remove the assignments from the branches
    |
-help: add a semicolon after the `if` expression
+LL ~     
+LL ~     let g: usize = if true {
+LL ~         5
+LL |     } else {
+LL |         panic!();
+LL ~     };
    |
-LL |     };
-   |      +
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:88:5
@@ -196,10 +179,12 @@ LL |     let y = SignificantDrop;
 LL |     x = 1;
    |     ^^^^^ initialised here
    |
-help: declare `x` here
+help: move the declaration `x` here
+   |
+LL ~     
+LL |     let y = SignificantDrop;
+LL ~     let x = 1;
    |
-LL |     let x = 1;
-   |     ~~~~~
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:92:5
@@ -210,10 +195,12 @@ LL |     let y = 1;
 LL |     x = SignificantDrop;
    |     ^^^^^^^^^^^^^^^^^^^ initialised here
    |
-help: declare `x` here
+help: move the declaration `x` here
+   |
+LL ~     
+LL |     let y = 1;
+LL ~     let x = SignificantDrop;
    |
-LL |     let x = SignificantDrop;
-   |     ~~~~~
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:96:5
@@ -224,10 +211,14 @@ LL |     let x;
 LL |     x = SignificantDrop;
    |     ^^^^^^^^^^^^^^^^^^^ initialised here
    |
-help: declare `x` here
+help: move the declaration `x` here
+   |
+LL ~     
+LL |     // types that should be considered insignificant
+ ...
+LL |     let y = Box::new(4);
+LL ~     let x = SignificantDrop;
    |
-LL |     let x = SignificantDrop;
-   |     ~~~~~
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:115:5
@@ -235,20 +226,17 @@ error: unneeded late initialization
 LL |     let a;
    |     ^^^^^^
    |
-help: declare `a` here
-   |
-LL |     let a = match n {
-   |     +++++++
-help: remove the assignments from the `match` arms
+help: move the declaration `a` here and remove the assignments from the `match` arms
    |
+LL ~     
+LL |     let n = 1;
+LL ~     let a = match n {
 LL ~         1 => f().await,
 LL |         _ => {
 LL ~             "two"
+LL |         },
+LL ~     };
    |
-help: add a semicolon after the `match` expression
-   |
-LL |     };
-   |      +
 
 error: unneeded late initialization
   --> tests/ui/needless_late_init.rs:132:5
@@ -256,20 +244,17 @@ error: unneeded late initialization
 LL |     let a;
    |     ^^^^^^
    |
-help: declare `a` here
-   |
-LL |     let a = match n {
-   |     +++++++
-help: remove the assignments from the `match` arms
+help: move the declaration `a` here and remove the assignments from the `match` arms
    |
+LL ~     
+LL |     let n = 1;
+LL ~     let a = match n {
 LL ~         1 => f(),
 LL |         _ => {
 LL ~             "two"
+LL |         },
+LL ~     };
    |
-help: add a semicolon after the `match` expression
-   |
-LL |     };
-   |      +
 
 error: aborting due to 16 previous errors