remove last statement special casing

Author: y21

clippy_lints/src/lib.rs

@@ -1172,6 +1172,7 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) {
     store.register_late_pass(move |_| Box::new(string_patterns::StringPatterns::new(msrv())));
     store.register_early_pass(|| Box::new(field_scoped_visibility_modifiers::FieldScopedVisibilityModifiers));
     store.register_late_pass(|_| Box::new(zombie_processes::ZombieProcesses));
+    // add lints here, do not remove this comment, it's used in `new_lint`
 }
 
 #[rustfmt::skip]

clippy_lints/src/zombie_processes.rs

@@ -60,19 +60,18 @@ impl<'tcx> LateLintPass<'tcx> for ZombieProcesses {
                     }
 
                     // Don't emit a suggestion since the binding is used later
-                    check(cx, expr, local.hir_id, false);
+                    check(cx, expr, false);
                 },
-                Node::LetStmt(&LetStmt { pat, hir_id, .. }) if let PatKind::Wild = pat.kind => {
+                Node::LetStmt(&LetStmt { pat, .. }) if let PatKind::Wild = pat.kind => {
                     // `let _ = child;`, also dropped immediately without `wait()`ing
-                    check(cx, expr, hir_id, true);
+                    check(cx, expr, true);
                 },
                 Node::Stmt(&Stmt {
                     kind: StmtKind::Semi(_),
-                    hir_id,
                     ..
                 }) => {
                     // Immediately dropped. E.g. `std::process::Command::new("echo").spawn().unwrap();`
-                    check(cx, expr, hir_id, true);
+                    check(cx, expr, true);
                 },
                 _ => {},
             }
@@ -101,6 +100,7 @@ enum BreakReason {
 /// - calling `id` or `kill`
 /// - no use at all (e.g. `let _x = child;`)
 /// - taking a shared reference (`&`), `wait()` can't go through that
+///
 /// None of these are sufficient to prevent zombie processes.
 /// Doing it like this means more FNs, but FNs are better than FPs.
 ///
@@ -212,9 +212,8 @@ impl<'a, 'tcx> Visitor<'tcx> for WaitFinder<'a, 'tcx> {
 /// such as checking that the binding is not used in certain ways, which isn't necessary for
 /// `let _ = <expr that spawns child>;`.
 ///
-/// This checks if the program doesn't unconditionally exit after the spawn expression and that it
-/// isn't the last statement of the program.
-fn check<'tcx>(cx: &LateContext<'tcx>, spawn_expr: &'tcx Expr<'tcx>, node_id: HirId, emit_suggestion: bool) {
+/// This checks if the program doesn't unconditionally exit after the spawn expression.
+fn check<'tcx>(cx: &LateContext<'tcx>, spawn_expr: &'tcx Expr<'tcx>, emit_suggestion: bool) {
     let Some(block) = get_enclosing_block(cx, spawn_expr.hir_id) else {
         return;
     };
@@ -228,12 +227,6 @@ fn check<'tcx>(cx: &LateContext<'tcx>, spawn_expr: &'tcx Expr<'tcx>, node_id: Hi
         return;
     }
 
-    // This might be the last effective node of the program (main function).
-    // There's no need to lint in that case either, as this is basically equivalent to calling `exit()`
-    if is_last_node_in_main(cx, node_id) {
-        return;
-    }
-
     span_lint_and_then(
         cx,
         ZOMBIE_PROCESSES,
@@ -257,26 +250,6 @@ fn check<'tcx>(cx: &LateContext<'tcx>, spawn_expr: &'tcx Expr<'tcx>, node_id: Hi
     );
 }
 
-/// The hir id id may either correspond to a `Local` or `Stmt`, depending on how we got here.
-/// This function gets the enclosing function, checks if it's `main` and if so,
-/// check if the last statement modulo blocks is the given id.
-fn is_last_node_in_main(cx: &LateContext<'_>, id: HirId) -> bool {
-    let hir = cx.tcx.hir();
-    let body_owner = hir.enclosing_body_owner(id);
-    let enclosing_body = hir.body_owned_by(body_owner);
-
-    if let Some((main_def_id, _)) = cx.tcx.entry_fn(())
-        && main_def_id == body_owner.to_def_id()
-        && let ExprKind::Block(block, _) = &enclosing_body.value.peel_blocks().kind
-        && let [.., stmt] = block.stmts
-    {
-        matches!(stmt.kind, StmtKind::Let(local) if local.hir_id == id)
-            || matches!(stmt.kind, StmtKind::Semi(..) if stmt.hir_id == id)
-    } else {
-        false
-    }
-}
-
 /// Checks if the given expression exits the process.
 fn is_exit_expression(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
     fn_def_id(cx, expr).is_some_and(|fn_did| {

tests/ui/zombie_processes.rs

@@ -131,15 +131,6 @@ fn main() {
         }
         x.wait().unwrap();
     }
-
-    // Checking that it won't lint if spawn is the last statement of a main function.
-    // IMPORTANT: this case must always be at the very end so it always tests the right thing.
-    // Don't move this.
-    {
-        {
-            Command::new("").spawn().unwrap();
-        }
-    }
 }
 
 fn process_child(c: Child) {

tests/ui/zombie_processes_fixable.fixed

@@ -1,4 +1,5 @@
 #![warn(clippy::zombie_processes)]
+#![allow(clippy::needless_return)]
 
 use std::process::{Child, Command};
 
@@ -19,3 +20,7 @@ fn not_main() {
 fn spawn_proc() -> Child {
     Command::new("").spawn().unwrap()
 }
+
+fn spawn_proc_2() -> Child {
+    return Command::new("").spawn().unwrap();
+}

tests/ui/zombie_processes_fixable.rs

@@ -1,4 +1,5 @@
 #![warn(clippy::zombie_processes)]
+#![allow(clippy::needless_return)]
 
 use std::process::{Child, Command};
 

tests/ui/zombie_processes_fixable.stderr

@@ -1,5 +1,5 @@
 error: spawned process is never `wait()`ed on
-  --> tests/ui/zombie_processes_fixable.rs:6:13
+  --> tests/ui/zombie_processes_fixable.rs:7:13
    |
 LL |     let _ = Command::new("").spawn().unwrap();
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- help: try: `.wait()`
@@ -10,7 +10,7 @@ LL |     let _ = Command::new("").spawn().unwrap();
    = help: to override `-D warnings` add `#[allow(clippy::zombie_processes)]`
 
 error: spawned process is never `wait()`ed on
-  --> tests/ui/zombie_processes_fixable.rs:8:5
+  --> tests/ui/zombie_processes_fixable.rs:9:5
    |
 LL |     Command::new("").spawn().unwrap();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- help: try: `.wait()`
@@ -19,7 +19,7 @@ LL |     Command::new("").spawn().unwrap();
    = note: see https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning
 
 error: spawned process is never `wait()`ed on
-  --> tests/ui/zombie_processes_fixable.rs:10:5
+  --> tests/ui/zombie_processes_fixable.rs:11:5
    |
 LL |     spawn_proc();
    |     ^^^^^^^^^^^^- help: try: `.wait()`
@@ -28,7 +28,7 @@ LL |     spawn_proc();
    = note: see https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning
 
 error: spawned process is never `wait()`ed on
-  --> tests/ui/zombie_processes_fixable.rs:16:5
+  --> tests/ui/zombie_processes_fixable.rs:17:5
    |
 LL |     Command::new("").spawn().unwrap();
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- help: try: `.wait()`