From e8ac4ea4187498052849531b86114a1eec5314a1 Mon Sep 17 00:00:00 2001 From: y21 <30553356+y21@users.noreply.github.com> Date: Sun, 10 Sep 2023 16:14:20 +0200 Subject: [PATCH] new lint: `zombie_processes` --- CHANGELOG.md | 1 + clippy_dev/src/serve.rs | 3 +- clippy_lints/src/declared_lints.rs | 1 + clippy_lints/src/lib.rs | 2 + clippy_lints/src/zombie_processes.rs | 334 +++++++++++++++++++ clippy_utils/src/paths.rs | 4 + tests/ui/suspicious_command_arg_space.fixed | 1 + tests/ui/suspicious_command_arg_space.rs | 1 + tests/ui/suspicious_command_arg_space.stderr | 4 +- tests/ui/zombie_processes.rs | 138 ++++++++ tests/ui/zombie_processes.stderr | 64 ++++ tests/ui/zombie_processes_fixable.fixed | 26 ++ tests/ui/zombie_processes_fixable.rs | 26 ++ tests/ui/zombie_processes_fixable.stderr | 40 +++ 14 files changed, 642 insertions(+), 3 deletions(-) create mode 100644 clippy_lints/src/zombie_processes.rs create mode 100644 tests/ui/zombie_processes.rs create mode 100644 tests/ui/zombie_processes.stderr create mode 100644 tests/ui/zombie_processes_fixable.fixed create mode 100644 tests/ui/zombie_processes_fixable.rs create mode 100644 tests/ui/zombie_processes_fixable.stderr diff --git a/CHANGELOG.md b/CHANGELOG.md index c5d7991e0..21252a3f4 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -6048,6 +6048,7 @@ Released 2018-09-13 [`zero_repeat_side_effects`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_repeat_side_effects [`zero_sized_map_values`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_sized_map_values [`zero_width_space`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_width_space +[`zombie_processes`]: https://rust-lang.github.io/rust-clippy/master/index.html#zombie_processes [`zst_offset`]: https://rust-lang.github.io/rust-clippy/master/index.html#zst_offset diff --git a/clippy_dev/src/serve.rs b/clippy_dev/src/serve.rs index 19560b31f..cc14cd8da 100644 --- a/clippy_dev/src/serve.rs +++ b/clippy_dev/src/serve.rs @@ -29,7 +29,7 @@ pub fn run(port: u16, lint: Option) -> ! { } if let Some(url) = url.take() { thread::spawn(move || { - Command::new(PYTHON) + let mut child = Command::new(PYTHON) .arg("-m") .arg("http.server") .arg(port.to_string()) @@ -40,6 +40,7 @@ pub fn run(port: u16, lint: Option) -> ! { thread::sleep(Duration::from_millis(500)); // Launch browser after first export.py has completed and http.server is up let _result = opener::open(url); + child.wait().unwrap(); }); } thread::sleep(Duration::from_millis(1000)); diff --git a/clippy_lints/src/declared_lints.rs b/clippy_lints/src/declared_lints.rs index 94da5752b..10e041fbc 100644 --- a/clippy_lints/src/declared_lints.rs +++ b/clippy_lints/src/declared_lints.rs @@ -768,4 +768,5 @@ pub static LINTS: &[&crate::LintInfo] = &[ crate::zero_div_zero::ZERO_DIVIDED_BY_ZERO_INFO, crate::zero_repeat_side_effects::ZERO_REPEAT_SIDE_EFFECTS_INFO, crate::zero_sized_map_values::ZERO_SIZED_MAP_VALUES_INFO, + crate::zombie_processes::ZOMBIE_PROCESSES_INFO, ]; diff --git a/clippy_lints/src/lib.rs b/clippy_lints/src/lib.rs index 2ac06b360..f24933683 100644 --- a/clippy_lints/src/lib.rs +++ b/clippy_lints/src/lib.rs @@ -386,6 +386,7 @@ mod write; mod zero_div_zero; mod zero_repeat_side_effects; mod zero_sized_map_values; +mod zombie_processes; // end lints modules, do not remove this comment, it’s used in `update_lints` use clippy_config::{get_configuration_metadata, Conf}; @@ -933,5 +934,6 @@ pub fn register_lints(store: &mut rustc_lint::LintStore, conf: &'static Conf) { store.register_late_pass(|_| Box::new(set_contains_or_insert::SetContainsOrInsert)); store.register_early_pass(|| Box::new(byte_char_slices::ByteCharSlice)); store.register_early_pass(|| Box::new(cfg_not_test::CfgNotTest)); + store.register_late_pass(|_| Box::new(zombie_processes::ZombieProcesses)); // add lints here, do not remove this comment, it's used in `new_lint` } diff --git a/clippy_lints/src/zombie_processes.rs b/clippy_lints/src/zombie_processes.rs new file mode 100644 index 000000000..eda3d7820 --- /dev/null +++ b/clippy_lints/src/zombie_processes.rs @@ -0,0 +1,334 @@ +use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::{fn_def_id, get_enclosing_block, match_any_def_paths, match_def_path, path_to_local_id, paths}; +use rustc_ast::Mutability; +use rustc_errors::Applicability; +use rustc_hir::intravisit::{walk_block, walk_expr, walk_local, Visitor}; +use rustc_hir::{Expr, ExprKind, HirId, LetStmt, Node, PatKind, Stmt, StmtKind}; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_session::declare_lint_pass; +use rustc_span::sym; +use std::ops::ControlFlow; +use ControlFlow::{Break, Continue}; + +declare_clippy_lint! { + /// ### What it does + /// Looks for code that spawns a process but never calls `wait()` on the child. + /// + /// ### Why is this bad? + /// As explained in the [standard library documentation](https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning), + /// calling `wait()` is necessary on Unix platforms to properly release all OS resources associated with the process. + /// Not doing so will effectively leak process IDs and/or other limited global resources, + /// which can eventually lead to resource exhaustion, so it's recommended to call `wait()` in long-running applications. + /// Such processes are called "zombie processes". + /// + /// ### Example + /// ```rust + /// use std::process::Command; + /// + /// let _child = Command::new("ls").spawn().expect("failed to execute child"); + /// ``` + /// Use instead: + /// ```rust + /// use std::process::Command; + /// + /// let mut child = Command::new("ls").spawn().expect("failed to execute child"); + /// child.wait().expect("failed to wait on child"); + /// ``` + #[clippy::version = "1.74.0"] + pub ZOMBIE_PROCESSES, + suspicious, + "not waiting on a spawned child process" +} +declare_lint_pass!(ZombieProcesses => [ZOMBIE_PROCESSES]); + +impl<'tcx> LateLintPass<'tcx> for ZombieProcesses { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) { + if let ExprKind::Call(..) | ExprKind::MethodCall(..) = expr.kind + && let Some(child_adt) = cx.typeck_results().expr_ty(expr).ty_adt_def() + && match_def_path(cx, child_adt.did(), &paths::CHILD) + { + match cx.tcx.parent_hir_node(expr.hir_id) { + Node::LetStmt(local) + if let PatKind::Binding(_, local_id, ..) = local.pat.kind + && let Some(enclosing_block) = get_enclosing_block(cx, expr.hir_id) => + { + let mut vis = WaitFinder::WalkUpTo(cx, local_id); + + // If it does have a `wait()` call, we're done. Don't lint. + if let Break(BreakReason::WaitFound) = walk_block(&mut vis, enclosing_block) { + return; + } + + // Don't emit a suggestion since the binding is used later + check(cx, expr, false); + }, + Node::LetStmt(&LetStmt { pat, .. }) if let PatKind::Wild = pat.kind => { + // `let _ = child;`, also dropped immediately without `wait()`ing + check(cx, expr, true); + }, + Node::Stmt(&Stmt { + kind: StmtKind::Semi(_), + .. + }) => { + // Immediately dropped. E.g. `std::process::Command::new("echo").spawn().unwrap();` + check(cx, expr, true); + }, + _ => {}, + } + } + } +} + +enum BreakReason { + WaitFound, + EarlyReturn, +} + +/// A visitor responsible for finding a `wait()` call on a local variable. +/// +/// Conditional `wait()` calls are assumed to not call wait: +/// ```ignore +/// let mut c = Command::new("").spawn().unwrap(); +/// if true { +/// c.wait(); +/// } +/// ``` +/// +/// Note that this visitor does NOT explicitly look for `wait()` calls directly, but rather does the +/// inverse -- checking if all uses of the local are either: +/// - a field access (`child.{stderr,stdin,stdout}`) +/// - 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. +/// +/// `return` expressions, conditional or not, short-circuit the visitor because +/// if a `wait()` call hadn't been found at that point, it might never reach one at a later point: +/// ```ignore +/// let mut c = Command::new("").spawn().unwrap(); +/// if true { +/// return; // Break(BreakReason::EarlyReturn) +/// } +/// c.wait(); // this might not be reachable +/// ``` +enum WaitFinder<'a, 'tcx> { + WalkUpTo(&'a LateContext<'tcx>, HirId), + Found(&'a LateContext<'tcx>, HirId), +} + +impl<'a, 'tcx> Visitor<'tcx> for WaitFinder<'a, 'tcx> { + type Result = ControlFlow; + + fn visit_local(&mut self, l: &'tcx LetStmt<'tcx>) -> Self::Result { + if let Self::WalkUpTo(cx, local_id) = *self + && let PatKind::Binding(_, pat_id, ..) = l.pat.kind + && local_id == pat_id + { + *self = Self::Found(cx, local_id); + } + + walk_local(self, l) + } + + fn visit_expr(&mut self, ex: &'tcx Expr<'tcx>) -> Self::Result { + let Self::Found(cx, local_id) = *self else { + return walk_expr(self, ex); + }; + + if path_to_local_id(ex, local_id) { + match cx.tcx.parent_hir_node(ex.hir_id) { + Node::Stmt(Stmt { + kind: StmtKind::Semi(_), + .. + }) => {}, + Node::Expr(expr) if let ExprKind::Field(..) = expr.kind => {}, + Node::Expr(expr) if let ExprKind::AddrOf(_, Mutability::Not, _) = expr.kind => {}, + Node::Expr(expr) + if let Some(fn_did) = fn_def_id(cx, expr) + && match_any_def_paths(cx, fn_did, &[&paths::CHILD_ID, &paths::CHILD_KILL]).is_some() => {}, + + // Conservatively assume that all other kinds of nodes call `.wait()` somehow. + _ => return Break(BreakReason::WaitFound), + } + } else { + match ex.kind { + ExprKind::Ret(..) => return Break(BreakReason::EarlyReturn), + ExprKind::If(cond, then, None) => { + walk_expr(self, cond)?; + + // A `wait()` call in an if expression with no else is not enough: + // + // let c = spawn(); + // if true { + // c.wait(); + // } + // + // This might not call wait(). However, early returns are propagated, + // because they might lead to a later wait() not being called. + if let Break(BreakReason::EarlyReturn) = walk_expr(self, then) { + return Break(BreakReason::EarlyReturn); + } + + return Continue(()); + }, + + ExprKind::If(cond, then, Some(else_)) => { + walk_expr(self, cond)?; + + #[expect(clippy::unnested_or_patterns)] + match (walk_expr(self, then), walk_expr(self, else_)) { + (Continue(()), Continue(())) + + // `wait()` in one branch but nothing in the other does not count + | (Continue(()), Break(BreakReason::WaitFound)) + | (Break(BreakReason::WaitFound), Continue(())) => {}, + + // `wait()` in both branches is ok + (Break(BreakReason::WaitFound), Break(BreakReason::WaitFound)) => { + return Break(BreakReason::WaitFound); + }, + + // Propagate early returns in either branch + (Break(BreakReason::EarlyReturn), _) | (_, Break(BreakReason::EarlyReturn)) => { + return Break(BreakReason::EarlyReturn); + }, + } + + return Continue(()); + }, + _ => {}, + } + } + + walk_expr(self, ex) + } +} + +/// This function has shared logic between the different kinds of nodes that can trigger the lint. +/// +/// In particular, `let = ;` requires some custom additional logic +/// such as checking that the binding is not used in certain ways, which isn't necessary for +/// `let _ = ;`. +/// +/// 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; + }; + + let mut vis = ExitPointFinder { + cx, + state: ExitPointState::WalkUpTo(spawn_expr.hir_id), + }; + if let Break(ExitCallFound) = vis.visit_block(block) { + // Visitor found an unconditional `exit()` call, so don't lint. + return; + } + + span_lint_and_then( + cx, + ZOMBIE_PROCESSES, + spawn_expr.span, + "spawned process is never `wait()`ed on", + |diag| { + if emit_suggestion { + diag.span_suggestion( + spawn_expr.span.shrink_to_hi(), + "try", + ".wait()", + Applicability::MaybeIncorrect, + ); + } else { + diag.note("consider calling `.wait()`"); + } + + diag.note("not doing so might leave behind zombie processes") + .note("see https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning"); + }, + ); +} + +/// 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| { + cx.tcx.is_diagnostic_item(sym::process_exit, fn_did) || match_def_path(cx, fn_did, &paths::ABORT) + }) +} + +#[derive(Debug)] +enum ExitPointState { + /// Still walking up to the expression that initiated the visitor. + WalkUpTo(HirId), + /// We're inside of a control flow construct (e.g. `if`, `match`, `loop`) + /// Within this, we shouldn't accept any `exit()` calls in here, but we can leave all of these + /// constructs later and still continue looking for an `exit()` call afterwards. Example: + /// ```ignore + /// Command::new("").spawn().unwrap(); + /// + /// if true { // depth=1 + /// if true { // depth=2 + /// match () { // depth=3 + /// () => loop { // depth=4 + /// + /// std::process::exit(); + /// ^^^^^^^^^^^^^^^^^^^^^ conditional exit call, ignored + /// + /// } // depth=3 + /// } // depth=2 + /// } // depth=1 + /// } // depth=0 + /// + /// std::process::exit(); + /// ^^^^^^^^^^^^^^^^^^^^^ this exit call is accepted because we're now unconditionally calling it + /// ``` + /// We can only get into this state from `NoExit`. + InControlFlow { depth: u32 }, + /// No exit call found yet, but looking for one. + NoExit, +} + +fn expr_enters_control_flow(expr: &Expr<'_>) -> bool { + matches!(expr.kind, ExprKind::If(..) | ExprKind::Match(..) | ExprKind::Loop(..)) +} + +struct ExitPointFinder<'a, 'tcx> { + state: ExitPointState, + cx: &'a LateContext<'tcx>, +} + +struct ExitCallFound; + +impl<'a, 'tcx> Visitor<'tcx> for ExitPointFinder<'a, 'tcx> { + type Result = ControlFlow; + + fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) -> Self::Result { + match self.state { + ExitPointState::WalkUpTo(id) if expr.hir_id == id => { + self.state = ExitPointState::NoExit; + walk_expr(self, expr) + }, + ExitPointState::NoExit if expr_enters_control_flow(expr) => { + self.state = ExitPointState::InControlFlow { depth: 1 }; + walk_expr(self, expr)?; + if let ExitPointState::InControlFlow { .. } = self.state { + self.state = ExitPointState::NoExit; + } + Continue(()) + }, + ExitPointState::NoExit if is_exit_expression(self.cx, expr) => Break(ExitCallFound), + ExitPointState::InControlFlow { ref mut depth } if expr_enters_control_flow(expr) => { + *depth += 1; + walk_expr(self, expr)?; + match self.state { + ExitPointState::InControlFlow { depth: 1 } => self.state = ExitPointState::NoExit, + ExitPointState::InControlFlow { ref mut depth } => *depth -= 1, + _ => {}, + } + Continue(()) + }, + _ => Continue(()), + } + } +} diff --git a/clippy_utils/src/paths.rs b/clippy_utils/src/paths.rs index a767798a9..930fb9fb6 100644 --- a/clippy_utils/src/paths.rs +++ b/clippy_utils/src/paths.rs @@ -4,6 +4,7 @@ //! Whenever possible, please consider diagnostic items over hardcoded paths. //! See for more information. +pub const ABORT: [&str; 3] = ["std", "process", "abort"]; pub const APPLICABILITY: [&str; 2] = ["rustc_lint_defs", "Applicability"]; pub const APPLICABILITY_VALUES: [[&str; 3]; 4] = [ ["rustc_lint_defs", "Applicability", "Unspecified"], @@ -23,6 +24,9 @@ pub const CORE_RESULT_OK_METHOD: [&str; 4] = ["core", "result", "Result", "ok"]; pub const CSTRING_AS_C_STR: [&str; 5] = ["alloc", "ffi", "c_str", "CString", "as_c_str"]; pub const EARLY_CONTEXT: [&str; 2] = ["rustc_lint", "EarlyContext"]; pub const EARLY_LINT_PASS: [&str; 3] = ["rustc_lint", "passes", "EarlyLintPass"]; +pub const CHILD: [&str; 3] = ["std", "process", "Child"]; +pub const CHILD_ID: [&str; 4] = ["std", "process", "Child", "id"]; +pub const CHILD_KILL: [&str; 4] = ["std", "process", "Child", "kill"]; pub const F32_EPSILON: [&str; 4] = ["core", "f32", "", "EPSILON"]; pub const F64_EPSILON: [&str; 4] = ["core", "f64", "", "EPSILON"]; pub const FILE_OPTIONS: [&str; 4] = ["std", "fs", "File", "options"]; diff --git a/tests/ui/suspicious_command_arg_space.fixed b/tests/ui/suspicious_command_arg_space.fixed index 5d7b1e0c1..704d6ea1b 100644 --- a/tests/ui/suspicious_command_arg_space.fixed +++ b/tests/ui/suspicious_command_arg_space.fixed @@ -1,3 +1,4 @@ +#![allow(clippy::zombie_processes)] fn main() { // Things it should warn about: std::process::Command::new("echo").args(["-n", "hello"]).spawn().unwrap(); diff --git a/tests/ui/suspicious_command_arg_space.rs b/tests/ui/suspicious_command_arg_space.rs index 8abd9803a..2a2a75573 100644 --- a/tests/ui/suspicious_command_arg_space.rs +++ b/tests/ui/suspicious_command_arg_space.rs @@ -1,3 +1,4 @@ +#![allow(clippy::zombie_processes)] fn main() { // Things it should warn about: std::process::Command::new("echo").arg("-n hello").spawn().unwrap(); diff --git a/tests/ui/suspicious_command_arg_space.stderr b/tests/ui/suspicious_command_arg_space.stderr index d2517b66b..6fd07d07d 100644 --- a/tests/ui/suspicious_command_arg_space.stderr +++ b/tests/ui/suspicious_command_arg_space.stderr @@ -1,5 +1,5 @@ error: single argument that looks like it should be multiple arguments - --> tests/ui/suspicious_command_arg_space.rs:3:44 + --> tests/ui/suspicious_command_arg_space.rs:4:44 | LL | std::process::Command::new("echo").arg("-n hello").spawn().unwrap(); | ^^^^^^^^^^ @@ -12,7 +12,7 @@ LL | std::process::Command::new("echo").args(["-n", "hello"]).spawn().unwrap | ~~~~ ~~~~~~~~~~~~~~~ error: single argument that looks like it should be multiple arguments - --> tests/ui/suspicious_command_arg_space.rs:6:43 + --> tests/ui/suspicious_command_arg_space.rs:7:43 | LL | std::process::Command::new("cat").arg("--number file").spawn().unwrap(); | ^^^^^^^^^^^^^^^ diff --git a/tests/ui/zombie_processes.rs b/tests/ui/zombie_processes.rs new file mode 100644 index 000000000..a2abc7fc3 --- /dev/null +++ b/tests/ui/zombie_processes.rs @@ -0,0 +1,138 @@ +#![warn(clippy::zombie_processes)] +#![allow(clippy::if_same_then_else, clippy::ifs_same_cond)] + +use std::process::{Child, Command}; + +fn main() { + { + // Check that #[expect] works + #[expect(clippy::zombie_processes)] + let mut x = Command::new("").spawn().unwrap(); + } + + { + let mut x = Command::new("").spawn().unwrap(); + //~^ ERROR: spawned process is never `wait()`ed on + x.kill(); + x.id(); + } + { + let mut x = Command::new("").spawn().unwrap(); + x.wait().unwrap(); // OK + } + { + let x = Command::new("").spawn().unwrap(); + x.wait_with_output().unwrap(); // OK + } + { + let mut x = Command::new("").spawn().unwrap(); + x.try_wait().unwrap(); // OK + } + { + let mut x = Command::new("").spawn().unwrap(); + let mut r = &mut x; + r.wait().unwrap(); // OK, not calling `.wait()` directly on `x` but through `r` -> `x` + } + { + let mut x = Command::new("").spawn().unwrap(); + process_child(x); // OK, other function might call `.wait()` so assume it does + } + { + let mut x = Command::new("").spawn().unwrap(); + //~^ ERROR: spawned process is never `wait()`ed on + let v = &x; + // (allow shared refs is fine because one cannot call `.wait()` through that) + } + + // https://github.com/rust-lang/rust-clippy/pull/11476#issuecomment-1718456033 + // Unconditionally exiting the process in various ways (should not lint) + { + let mut x = Command::new("").spawn().unwrap(); + std::process::exit(0); + } + { + let mut x = Command::new("").spawn().unwrap(); + std::process::abort(); // same as above, but abort instead of exit + } + { + let mut x = Command::new("").spawn().unwrap(); + if true { /* nothing */ } + std::process::abort(); // still unconditionally exits + } + + // Conditionally exiting + // It should assume that it might not exit and still lint + { + let mut x = Command::new("").spawn().unwrap(); + //~^ ERROR: spawned process is never `wait()`ed on + if true { + std::process::exit(0); + } + } + { + let mut x = Command::new("").spawn().unwrap(); + //~^ ERROR: spawned process is never `wait()`ed on + if true { + while false {} + // Calling `exit()` after leaving a while loop should still be linted. + std::process::exit(0); + } + } + + { + let mut x = { Command::new("").spawn().unwrap() }; + x.wait().unwrap(); + } + + { + struct S { + c: Child, + } + + let mut s = S { + c: Command::new("").spawn().unwrap(), + }; + s.c.wait().unwrap(); + } + + { + let mut x = Command::new("").spawn().unwrap(); + //~^ ERROR: spawned process is never `wait()`ed on + if true { + return; + } + x.wait().unwrap(); + } + + { + let mut x = Command::new("").spawn().unwrap(); + //~^ ERROR: spawned process is never `wait()`ed on + if true { + x.wait().unwrap(); + } + } + + { + let mut x = Command::new("").spawn().unwrap(); + if true { + x.wait().unwrap(); + } else if true { + x.wait().unwrap(); + } else { + x.wait().unwrap(); + } + } + + { + let mut x = Command::new("").spawn().unwrap(); + if true { + x.wait().unwrap(); + return; + } + x.wait().unwrap(); + } +} + +fn process_child(c: Child) { + todo!() +} diff --git a/tests/ui/zombie_processes.stderr b/tests/ui/zombie_processes.stderr new file mode 100644 index 000000000..eec821a4c --- /dev/null +++ b/tests/ui/zombie_processes.stderr @@ -0,0 +1,64 @@ +error: spawned process is never `wait()`ed on + --> tests/ui/zombie_processes.rs:14:21 + | +LL | let mut x = Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: consider calling `.wait()` + = note: not doing so might leave behind zombie processes + = note: see https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning + = note: `-D clippy::zombie-processes` implied by `-D warnings` + = help: to override `-D warnings` add `#[allow(clippy::zombie_processes)]` + +error: spawned process is never `wait()`ed on + --> tests/ui/zombie_processes.rs:41:21 + | +LL | let mut x = Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: consider calling `.wait()` + = note: not doing so might leave behind zombie processes + = 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.rs:66:21 + | +LL | let mut x = Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: consider calling `.wait()` + = note: not doing so might leave behind zombie processes + = 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.rs:73:21 + | +LL | let mut x = Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: consider calling `.wait()` + = note: not doing so might leave behind zombie processes + = 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.rs:99:21 + | +LL | let mut x = Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: consider calling `.wait()` + = note: not doing so might leave behind zombie processes + = 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.rs:108:21 + | +LL | let mut x = Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: consider calling `.wait()` + = note: not doing so might leave behind zombie processes + = note: see https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning + +error: aborting due to 6 previous errors + diff --git a/tests/ui/zombie_processes_fixable.fixed b/tests/ui/zombie_processes_fixable.fixed new file mode 100644 index 000000000..6045262f5 --- /dev/null +++ b/tests/ui/zombie_processes_fixable.fixed @@ -0,0 +1,26 @@ +#![warn(clippy::zombie_processes)] +#![allow(clippy::needless_return)] + +use std::process::{Child, Command}; + +fn main() { + let _ = Command::new("").spawn().unwrap().wait(); + //~^ ERROR: spawned process is never `wait()`ed on + Command::new("").spawn().unwrap().wait(); + //~^ ERROR: spawned process is never `wait()`ed on + spawn_proc().wait(); + //~^ ERROR: spawned process is never `wait()`ed on + spawn_proc().wait().unwrap(); // OK +} + +fn not_main() { + Command::new("").spawn().unwrap().wait(); +} + +fn spawn_proc() -> Child { + Command::new("").spawn().unwrap() +} + +fn spawn_proc_2() -> Child { + return Command::new("").spawn().unwrap(); +} diff --git a/tests/ui/zombie_processes_fixable.rs b/tests/ui/zombie_processes_fixable.rs new file mode 100644 index 000000000..e1ecb7716 --- /dev/null +++ b/tests/ui/zombie_processes_fixable.rs @@ -0,0 +1,26 @@ +#![warn(clippy::zombie_processes)] +#![allow(clippy::needless_return)] + +use std::process::{Child, Command}; + +fn main() { + let _ = Command::new("").spawn().unwrap(); + //~^ ERROR: spawned process is never `wait()`ed on + Command::new("").spawn().unwrap(); + //~^ ERROR: spawned process is never `wait()`ed on + spawn_proc(); + //~^ ERROR: spawned process is never `wait()`ed on + spawn_proc().wait().unwrap(); // OK +} + +fn not_main() { + Command::new("").spawn().unwrap(); +} + +fn spawn_proc() -> Child { + Command::new("").spawn().unwrap() +} + +fn spawn_proc_2() -> Child { + return Command::new("").spawn().unwrap(); +} diff --git a/tests/ui/zombie_processes_fixable.stderr b/tests/ui/zombie_processes_fixable.stderr new file mode 100644 index 000000000..e1c40472c --- /dev/null +++ b/tests/ui/zombie_processes_fixable.stderr @@ -0,0 +1,40 @@ +error: spawned process is never `wait()`ed on + --> tests/ui/zombie_processes_fixable.rs:7:13 + | +LL | let _ = Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- help: try: `.wait()` + | + = note: not doing so might leave behind zombie processes + = note: see https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning + = note: `-D clippy::zombie-processes` implied by `-D warnings` + = help: to override `-D warnings` add `#[allow(clippy::zombie_processes)]` + +error: spawned process is never `wait()`ed on + --> tests/ui/zombie_processes_fixable.rs:9:5 + | +LL | Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- help: try: `.wait()` + | + = note: not doing so might leave behind zombie processes + = 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:11:5 + | +LL | spawn_proc(); + | ^^^^^^^^^^^^- help: try: `.wait()` + | + = note: not doing so might leave behind zombie processes + = 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:17:5 + | +LL | Command::new("").spawn().unwrap(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^- help: try: `.wait()` + | + = note: not doing so might leave behind zombie processes + = note: see https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning + +error: aborting due to 4 previous errors +