From 3c8bfd144b7b740f7cde10b14ea86fc1dbc7ce63 Mon Sep 17 00:00:00 2001
From: Samuel Tardieu <sam@rfc1149.net>
Date: Wed, 28 May 2025 20:18:22 +0200
Subject: [PATCH] `zombie_processes`: do not complain about early early returns

If an early return is found under the HIR local declaration node but
before the child process is created, it should not trigger the lint
because the child process has not yet been created.
---
 clippy_lints/src/zombie_processes.rs | 26 +++++++++++---------------
 tests/ui/zombie_processes.rs         | 10 ++++++++++
 2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/clippy_lints/src/zombie_processes.rs b/clippy_lints/src/zombie_processes.rs
index 09f1084fe700..6ab94a522109 100644
--- a/clippy_lints/src/zombie_processes.rs
+++ b/clippy_lints/src/zombie_processes.rs
@@ -5,7 +5,7 @@ use rustc_ast::Mutability;
 use rustc_ast::visit::visit_opt;
 use rustc_errors::Applicability;
 use rustc_hir::def_id::LocalDefId;
-use rustc_hir::intravisit::{Visitor, walk_block, walk_expr, walk_local};
+use rustc_hir::intravisit::{Visitor, walk_block, walk_expr};
 use rustc_hir::{Expr, ExprKind, HirId, LetStmt, Node, PatKind, Stmt, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::hir::nested_filter;
@@ -69,8 +69,9 @@ impl<'tcx> LateLintPass<'tcx> for ZombieProcesses {
                     let mut vis = WaitFinder {
                         cx,
                         local_id,
+                        create_id: expr.hir_id,
                         body_id: cx.tcx.hir_enclosing_body_owner(expr.hir_id),
-                        state: VisitorState::WalkUpToLocal,
+                        state: VisitorState::WalkUpToCreate,
                         early_return: None,
                         missing_wait_branch: None,
                     };
@@ -131,6 +132,7 @@ struct MaybeWait(Span);
 struct WaitFinder<'a, 'tcx> {
     cx: &'a LateContext<'tcx>,
     local_id: HirId,
+    create_id: HirId,
     body_id: LocalDefId,
     state: VisitorState,
     early_return: Option<Span>,
@@ -141,8 +143,8 @@ struct WaitFinder<'a, 'tcx> {
 
 #[derive(PartialEq)]
 enum VisitorState {
-    WalkUpToLocal,
-    LocalFound,
+    WalkUpToCreate,
+    CreateFound,
 }
 
 #[derive(Copy, Clone)]
@@ -155,19 +157,13 @@ impl<'tcx> Visitor<'tcx> for WaitFinder<'_, 'tcx> {
     type NestedFilter = nested_filter::OnlyBodies;
     type Result = ControlFlow<MaybeWait>;
 
-    fn visit_local(&mut self, l: &'tcx LetStmt<'tcx>) -> Self::Result {
-        if self.state == VisitorState::WalkUpToLocal
-            && let PatKind::Binding(_, pat_id, ..) = l.pat.kind
-            && self.local_id == pat_id
-        {
-            self.state = VisitorState::LocalFound;
+    fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) -> Self::Result {
+        if ex.hir_id == self.create_id {
+            self.state = VisitorState::CreateFound;
+            return Continue(());
         }
 
-        walk_local(self, l)
-    }
-
-    fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) -> Self::Result {
-        if self.state != VisitorState::LocalFound {
+        if self.state != VisitorState::CreateFound {
             return walk_expr(self, ex);
         }
 
diff --git a/tests/ui/zombie_processes.rs b/tests/ui/zombie_processes.rs
index 395f9dd2defb..e81b5fd4f3e2 100644
--- a/tests/ui/zombie_processes.rs
+++ b/tests/ui/zombie_processes.rs
@@ -198,3 +198,13 @@ mod issue14677 {
         child.wait().unwrap();
     }
 }
+
+fn issue14911() -> std::io::Result<String> {
+    let (mut recv, send) = std::io::pipe()?;
+    let mut command = Command::new("ls")
+        .stdout(send.try_clone()?)
+        .spawn()
+        .expect("Could not spawn new process...");
+    command.wait()?;
+    Ok("".into())
+}