52 lines
1.9 KiB
Rust
52 lines
1.9 KiB
Rust
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use crate::utils::{
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derefs_to_slice, is_type_diagnostic_item, match_trait_method, method_chain_args, paths, snippet_with_applicability,
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span_lint_and_sugg,
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};
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::Expr;
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use rustc_lint::LateContext;
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use rustc_span::sym;
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use super::ITER_COUNT;
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pub(crate) fn lints<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, iter_args: &'tcx [Expr<'tcx>], is_mut: bool) {
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let mut_str = if is_mut { "_mut" } else { "" };
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let iter_method = if method_chain_args(expr, &[format!("iter{}", mut_str).as_str(), "count"]).is_some() {
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"iter"
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} else if method_chain_args(expr, &["into_iter", "count"]).is_some() {
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"into_iter"
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} else {
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return;
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};
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if_chain! {
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let caller_type = if derefs_to_slice(cx, &iter_args[0], cx.typeck_results().expr_ty(&iter_args[0])).is_some() {
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Some("slice")
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} else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym::vec_type) {
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Some("Vec")
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} else if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&iter_args[0]), sym!(vecdeque_type)) {
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Some("VecDeque")
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} else if match_trait_method(cx, expr, &paths::ITERATOR) {
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Some("std::iter::Iterator")
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} else {
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None
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};
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if let Some(caller_type) = caller_type;
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then {
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let mut applicability = Applicability::MachineApplicable;
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span_lint_and_sugg(
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cx,
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ITER_COUNT,
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expr.span,
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&format!("called `.{}{}().count()` on a `{}`", iter_method, mut_str, caller_type),
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"try",
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format!(
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"{}.len()",
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snippet_with_applicability(cx, iter_args[0].span, "..", &mut applicability),
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),
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applicability,
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);
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}
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}
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}
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