diff --git a/clippy_lints/src/misc_early.rs b/clippy_lints/src/misc_early.rs index b84a1a3fe24..125df226ceb 100644 --- a/clippy_lints/src/misc_early.rs +++ b/clippy_lints/src/misc_early.rs @@ -14,6 +14,7 @@ use rustc_lint::{EarlyContext, EarlyLintPass, LintContext}; use rustc_middle::lint::in_external_macro; use rustc_session::{declare_lint_pass, declare_tool_lint}; use rustc_span::source_map::Span; +use rustc_span::symbol::Ident; declare_clippy_lint! { /// **What it does:** Checks for structure field patterns bound to wildcards. @@ -493,6 +494,29 @@ impl EarlyLintPass for MiscEarlyLints { } fn check_block(&mut self, cx: &EarlyContext<'_>, block: &Block) { + fn count_closure_usage(block: &Block, ident: &Ident) -> usize { + struct ClosureUsageCount<'ast> { + ident: &'ast Ident, + count: usize, + }; + impl<'ast> Visitor<'ast> for ClosureUsageCount<'ast> { + fn visit_expr(&mut self, expr: &'ast Expr) { + if_chain! { + if let ExprKind::Call(ref closure, _) = expr.kind; + if let ExprKind::Path(_, ref path) = closure.kind; + if self.ident == &path.segments[0].ident; + then { + self.count += 1; + } + } + walk_expr(self, expr); + } + } + let mut closure_usage_count = ClosureUsageCount { ident, count: 0 }; + closure_usage_count.visit_block(block); + closure_usage_count.count + } + for w in block.stmts.windows(2) { if_chain! { if let StmtKind::Local(ref local) = w[0].kind; @@ -503,15 +527,15 @@ impl EarlyLintPass for MiscEarlyLints { if let ExprKind::Assign(_, ref call, _) = second.kind; if let ExprKind::Call(ref closure, _) = call.kind; if let ExprKind::Path(_, ref path) = closure.kind; + if ident == path.segments[0].ident; + if count_closure_usage(block, &ident) == 1; then { - if ident == path.segments[0].ident { - span_lint( - cx, - REDUNDANT_CLOSURE_CALL, - second.span, - "Closure called just once immediately after it was declared", - ); - } + span_lint( + cx, + REDUNDANT_CLOSURE_CALL, + second.span, + "Closure called just once immediately after it was declared", + ); } } } diff --git a/tests/ui/redundant_closure_call.rs b/tests/ui/redundant_closure_call.rs index bacd67db7c3..0f2ba4a075d 100644 --- a/tests/ui/redundant_closure_call.rs +++ b/tests/ui/redundant_closure_call.rs @@ -8,14 +8,21 @@ fn main() { k = (|a, b| a * b)(1, 5); - let closure = || 32; - i = closure(); - + // don't lint here, the closure is used more than once let closure = |i| i + 1; i = closure(3); - i = closure(4); + // lint here + let redun_closure = || 1; + i = redun_closure(); + + // the lint is applicable here but the lint doesn't support redefinition + let redefined_closure = || 1; + i = redefined_closure(); + let redefined_closure = || 2; + i = redefined_closure(); + #[allow(clippy::needless_return)] (|| return 2)(); (|| -> Option { None? })(); diff --git a/tests/ui/redundant_closure_call.stderr b/tests/ui/redundant_closure_call.stderr index 68c1416bb6b..d5e0664319b 100644 --- a/tests/ui/redundant_closure_call.stderr +++ b/tests/ui/redundant_closure_call.stderr @@ -1,17 +1,11 @@ error: Closure called just once immediately after it was declared - --> $DIR/redundant_closure_call.rs:12:5 + --> $DIR/redundant_closure_call.rs:18:5 | -LL | i = closure(); - | ^^^^^^^^^^^^^ +LL | i = redun_closure(); + | ^^^^^^^^^^^^^^^^^^^ | = note: `-D clippy::redundant-closure-call` implied by `-D warnings` -error: Closure called just once immediately after it was declared - --> $DIR/redundant_closure_call.rs:15:5 - | -LL | i = closure(3); - | ^^^^^^^^^^^^^^ - error: Try not to call a closure in the expression where it is declared. --> $DIR/redundant_closure_call.rs:7:17 | @@ -24,5 +18,5 @@ error: Try not to call a closure in the expression where it is declared. LL | k = (|a, b| a * b)(1, 5); | ^^^^^^^^^^^^^^^^^^^^ -error: aborting due to 4 previous errors +error: aborting due to 3 previous errors