diff options
| -rw-r--r-- | clippy_lints/src/methods/mod.rs | 18 | ||||
| -rw-r--r-- | tests/ui/unnecessary_fold.rs | 7 |
2 files changed, 25 insertions, 0 deletions
diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index 7c15eb677cc..66c94746f5a 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -9,6 +9,7 @@ use crate::rustc::hir; +use crate::rustc::hir::{ExprKind, Guard, Node}; use crate::rustc::hir::def::Def; use crate::rustc::lint::{in_external_macro, LateContext, LateLintPass, Lint, LintArray, LintContext, LintPass}; use crate::rustc::ty::{self, Ty}; @@ -1428,6 +1429,23 @@ fn lint_unnecessary_fold(cx: &LateContext<'_, '_>, expr: &hir::Expr, fold_args: return; } + // `Iterator::any` cannot be used within a pattern guard + // See https://github.com/rust-lang-nursery/rust-clippy/issues/3069 + if_chain! { + if let Some(fold_parent) = cx.tcx.hir.find(cx.tcx.hir.get_parent_node(expr.id)); + if let Node::Expr(fold_parent) = fold_parent; + if let ExprKind::Match(_, ref arms, _) = fold_parent.node; + if arms.iter().any(|arm| { + if let Some(Guard::If(ref guard)) = arm.guard { + return guard.id == expr.id; + } + false + }); + then { + return; + } + } + assert!(fold_args.len() == 3, "Expected fold_args to have three entries - the receiver, the initial value and the closure"); diff --git a/tests/ui/unnecessary_fold.rs b/tests/ui/unnecessary_fold.rs index e8d84ecea8c..3b70602d4ad 100644 --- a/tests/ui/unnecessary_fold.rs +++ b/tests/ui/unnecessary_fold.rs @@ -45,6 +45,13 @@ fn unnecessary_fold_should_ignore() { let _ = [(0..2), (0..3)].iter().fold(0, |a, b| a + b.len()); let _ = [(0..2), (0..3)].iter().fold(1, |a, b| a * b.len()); + + // Because `any` takes the iterator as a mutable reference, + // it cannot be used in a pattern guard, and we must use `fold`. + match 1 { + _ if (0..3).fold(false, |acc, x| acc || x > 2) => {} + _ => {} + } } fn main() {} |