31 lines
1.2 KiB
Rust
31 lines
1.2 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_help;
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use clippy_utils::usage::mutated_variables;
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use clippy_utils::{expr_or_init, is_trait_method};
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use rustc_hir as hir;
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use rustc_lint::LateContext;
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use rustc_span::sym;
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use super::SUSPICIOUS_MAP;
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pub fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, count_recv: &hir::Expr<'_>, map_arg: &hir::Expr<'_>) {
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if is_trait_method(cx, count_recv, sym::Iterator)
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&& let hir::ExprKind::Closure(closure) = expr_or_init(cx, map_arg).kind
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&& let closure_body = cx.tcx.hir_body(closure.body)
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&& !cx.typeck_results().expr_ty(closure_body.value).is_unit()
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{
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if let Some(map_mutated_vars) = mutated_variables(closure_body.value, cx)
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// A variable is used mutably inside of the closure. Suppress the lint.
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&& !map_mutated_vars.is_empty()
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{
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return;
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}
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span_lint_and_help(
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cx,
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SUSPICIOUS_MAP,
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expr.span,
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"this call to `map()` won't have an effect on the call to `count()`",
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None,
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"make sure you did not confuse `map` with `filter`, `for_each` or `inspect`",
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);
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}
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}
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