diff options
| -rw-r--r-- | clippy_lints/src/if_let_mutex.rs | 50 | ||||
| -rw-r--r-- | tests/ui/if_let_mutex.rs | 8 | ||||
| -rw-r--r-- | tests/ui/if_let_mutex.stderr | 30 |
3 files changed, 61 insertions, 27 deletions
diff --git a/clippy_lints/src/if_let_mutex.rs b/clippy_lints/src/if_let_mutex.rs index e9501700784..4d703d691ac 100644 --- a/clippy_lints/src/if_let_mutex.rs +++ b/clippy_lints/src/if_let_mutex.rs @@ -1,8 +1,9 @@ -use clippy_utils::diagnostics::span_lint_and_help; +use clippy_utils::diagnostics::span_lint_and_then; use clippy_utils::higher; use clippy_utils::ty::is_type_diagnostic_item; use clippy_utils::SpanlessEq; use if_chain::if_chain; +use rustc_errors::Diagnostic; use rustc_hir::intravisit::{self as visit, Visitor}; use rustc_hir::{Expr, ExprKind}; use rustc_lint::{LateContext, LateLintPass}; @@ -45,16 +46,8 @@ declare_lint_pass!(IfLetMutex => [IF_LET_MUTEX]); impl<'tcx> LateLintPass<'tcx> for IfLetMutex { fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) { - let mut arm_visit = ArmVisitor { - mutex_lock_called: false, - found_mutex: None, - cx, - }; - let mut op_visit = OppVisitor { - mutex_lock_called: false, - found_mutex: None, - cx, - }; + let mut arm_visit = ArmVisitor { found_mutex: None, cx }; + let mut op_visit = OppVisitor { found_mutex: None, cx }; if let Some(higher::IfLet { let_expr, if_then, @@ -63,18 +56,28 @@ impl<'tcx> LateLintPass<'tcx> for IfLetMutex { }) = higher::IfLet::hir(cx, expr) { op_visit.visit_expr(let_expr); - if op_visit.mutex_lock_called { + if let Some(op_mutex) = op_visit.found_mutex { arm_visit.visit_expr(if_then); arm_visit.visit_expr(if_else); - if arm_visit.mutex_lock_called && arm_visit.same_mutex(cx, op_visit.found_mutex.unwrap()) { - span_lint_and_help( + if let Some(arm_mutex) = arm_visit.found_mutex_if_same_as(op_mutex) { + let diag = |diag: &mut Diagnostic| { + diag.span_label( + op_mutex.span, + "this Mutex will remain locked for the entire `if let`-block...", + ); + diag.span_label( + arm_mutex.span, + "... and is tried to lock again here, which will always deadlock.", + ); + diag.help("move the lock call outside of the `if let ...` expression"); + }; + span_lint_and_then( cx, IF_LET_MUTEX, expr.span, "calling `Mutex::lock` inside the scope of another `Mutex::lock` causes a deadlock", - None, - "move the lock call outside of the `if let ...` expression", + diag, ); } } @@ -84,7 +87,6 @@ impl<'tcx> LateLintPass<'tcx> for IfLetMutex { /// Checks if `Mutex::lock` is called in the `if let` expr. pub struct OppVisitor<'a, 'tcx> { - mutex_lock_called: bool, found_mutex: Option<&'tcx Expr<'tcx>>, cx: &'a LateContext<'tcx>, } @@ -93,7 +95,6 @@ impl<'tcx> Visitor<'tcx> for OppVisitor<'_, 'tcx> { fn visit_expr(&mut self, expr: &'tcx Expr<'_>) { if let Some(mutex) = is_mutex_lock_call(self.cx, expr) { self.found_mutex = Some(mutex); - self.mutex_lock_called = true; return; } visit::walk_expr(self, expr); @@ -102,7 +103,6 @@ impl<'tcx> Visitor<'tcx> for OppVisitor<'_, 'tcx> { /// Checks if `Mutex::lock` is called in any of the branches. pub struct ArmVisitor<'a, 'tcx> { - mutex_lock_called: bool, found_mutex: Option<&'tcx Expr<'tcx>>, cx: &'a LateContext<'tcx>, } @@ -111,7 +111,6 @@ impl<'tcx> Visitor<'tcx> for ArmVisitor<'_, 'tcx> { fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) { if let Some(mutex) = is_mutex_lock_call(self.cx, expr) { self.found_mutex = Some(mutex); - self.mutex_lock_called = true; return; } visit::walk_expr(self, expr); @@ -119,9 +118,12 @@ impl<'tcx> Visitor<'tcx> for ArmVisitor<'_, 'tcx> { } impl<'tcx, 'l> ArmVisitor<'tcx, 'l> { - fn same_mutex(&self, cx: &LateContext<'_>, op_mutex: &Expr<'_>) -> bool { - self.found_mutex - .map_or(false, |arm_mutex| SpanlessEq::new(cx).eq_expr(op_mutex, arm_mutex)) + fn found_mutex_if_same_as(&self, op_mutex: &Expr<'_>) -> Option<&Expr<'_>> { + self.found_mutex.and_then(|arm_mutex| { + SpanlessEq::new(self.cx) + .eq_expr(op_mutex, arm_mutex) + .then_some(arm_mutex) + }) } } @@ -129,7 +131,7 @@ fn is_mutex_lock_call<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Opt if_chain! { if let ExprKind::MethodCall(path, [self_arg, ..], _) = &expr.kind; if path.ident.as_str() == "lock"; - let ty = cx.typeck_results().expr_ty(self_arg); + let ty = cx.typeck_results().expr_ty(self_arg).peel_refs(); if is_type_diagnostic_item(cx, ty, sym::Mutex); then { Some(self_arg) diff --git a/tests/ui/if_let_mutex.rs b/tests/ui/if_let_mutex.rs index 6cbfafbb38b..321feb0224e 100644 --- a/tests/ui/if_let_mutex.rs +++ b/tests/ui/if_let_mutex.rs @@ -39,4 +39,12 @@ fn if_let_different_mutex() { }; } +fn mutex_ref(mutex: &Mutex<i32>) { + if let Ok(i) = mutex.lock() { + do_stuff(i); + } else { + let _x = mutex.lock(); + }; +} + fn main() {} diff --git a/tests/ui/if_let_mutex.stderr b/tests/ui/if_let_mutex.stderr index e9c4d916332..8a4d5dbac59 100644 --- a/tests/ui/if_let_mutex.stderr +++ b/tests/ui/if_let_mutex.stderr @@ -1,10 +1,14 @@ error: calling `Mutex::lock` inside the scope of another `Mutex::lock` causes a deadlock --> $DIR/if_let_mutex.rs:10:5 | -LL | / if let Err(locked) = m.lock() { +LL | if let Err(locked) = m.lock() { + | ^ - this Mutex will remain locked for the entire `if let`-block... + | _____| + | | LL | | do_stuff(locked); LL | | } else { LL | | let lock = m.lock().unwrap(); + | | - ... and is tried to lock again here, which will always deadlock. LL | | do_stuff(lock); LL | | }; | |_____^ @@ -15,15 +19,35 @@ LL | | }; error: calling `Mutex::lock` inside the scope of another `Mutex::lock` causes a deadlock --> $DIR/if_let_mutex.rs:22:5 | -LL | / if let Some(locked) = m.lock().unwrap().deref() { +LL | if let Some(locked) = m.lock().unwrap().deref() { + | ^ - this Mutex will remain locked for the entire `if let`-block... + | _____| + | | LL | | do_stuff(locked); LL | | } else { LL | | let lock = m.lock().unwrap(); + | | - ... and is tried to lock again here, which will always deadlock. LL | | do_stuff(lock); LL | | }; | |_____^ | = help: move the lock call outside of the `if let ...` expression -error: aborting due to 2 previous errors +error: calling `Mutex::lock` inside the scope of another `Mutex::lock` causes a deadlock + --> $DIR/if_let_mutex.rs:43:5 + | +LL | if let Ok(i) = mutex.lock() { + | ^ ----- this Mutex will remain locked for the entire `if let`-block... + | _____| + | | +LL | | do_stuff(i); +LL | | } else { +LL | | let _x = mutex.lock(); + | | ----- ... and is tried to lock again here, which will always deadlock. +LL | | }; + | |_____^ + | + = help: move the lock call outside of the `if let ...` expression + +error: aborting due to 3 previous errors |