63 lines
1.8 KiB
Rust
63 lines
1.8 KiB
Rust
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::source::snippet;
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use clippy_utils::ty::{get_iterator_item_ty, is_copy};
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use itertools::Itertools;
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_lint::LateContext;
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use rustc_middle::ty;
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use std::ops::Not;
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use super::ITER_OVEREAGER_CLONED;
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use crate::redundant_clone::REDUNDANT_CLONE;
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/// lint overeager use of `cloned()` for `Iterator`s
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pub(super) fn check<'tcx>(
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cx: &LateContext<'tcx>,
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expr: &'tcx hir::Expr<'_>,
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recv: &'tcx hir::Expr<'_>,
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name: &str,
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map_arg: &[hir::Expr<'_>],
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) {
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// Check if it's iterator and get type associated with `Item`.
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let inner_ty = match get_iterator_item_ty(cx, cx.typeck_results().expr_ty_adjusted(recv)) {
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Some(ty) => ty,
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_ => return,
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};
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match inner_ty.kind() {
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ty::Ref(_, ty, _) if !is_copy(cx, ty) => {},
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_ => return,
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};
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let (lint, preserve_cloned) = match name {
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"count" => (REDUNDANT_CLONE, false),
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_ => (ITER_OVEREAGER_CLONED, true),
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};
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let wildcard_params = map_arg.is_empty().not().then(|| "...").unwrap_or_default();
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let msg = format!(
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"called `cloned().{}({})` on an `Iterator`. It may be more efficient to call `{}({}){}` instead",
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name,
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wildcard_params,
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name,
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wildcard_params,
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preserve_cloned.then(|| ".cloned()").unwrap_or_default(),
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);
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span_lint_and_sugg(
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cx,
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lint,
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expr.span,
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&msg,
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"try this",
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format!(
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"{}.{}({}){}",
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snippet(cx, recv.span, ".."),
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name,
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map_arg.iter().map(|a| snippet(cx, a.span, "..")).join(", "),
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preserve_cloned.then(|| ".cloned()").unwrap_or_default(),
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),
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Applicability::MachineApplicable,
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);
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}
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