71 lines
2.6 KiB
Rust
71 lines
2.6 KiB
Rust
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::source::snippet_with_applicability;
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use clippy_utils::ty::match_type;
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use clippy_utils::visitors::is_local_used;
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use clippy_utils::{path_to_local_id, paths, peel_blocks, peel_ref_operators, strip_pat_refs};
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::{BinOpKind, Closure, Expr, ExprKind, PatKind};
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use rustc_lint::LateContext;
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use rustc_middle::ty::{self, UintTy};
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use rustc_span::sym;
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use super::NAIVE_BYTECOUNT;
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pub(super) fn check<'tcx>(
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cx: &LateContext<'tcx>,
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expr: &'tcx Expr<'_>,
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filter_recv: &'tcx Expr<'_>,
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filter_arg: &'tcx Expr<'_>,
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) {
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if_chain! {
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if let ExprKind::Closure(&Closure { body, .. }) = filter_arg.kind;
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let body = cx.tcx.hir().body(body);
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if let [param] = body.params;
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if let PatKind::Binding(_, arg_id, _, _) = strip_pat_refs(param.pat).kind;
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if let ExprKind::Binary(ref op, l, r) = body.value.kind;
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if op.node == BinOpKind::Eq;
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if match_type(cx,
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cx.typeck_results().expr_ty(filter_recv).peel_refs(),
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&paths::SLICE_ITER);
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let operand_is_arg = |expr| {
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let expr = peel_ref_operators(cx, peel_blocks(expr));
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path_to_local_id(expr, arg_id)
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};
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let needle = if operand_is_arg(l) {
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r
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} else if operand_is_arg(r) {
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l
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} else {
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return;
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};
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if ty::Uint(UintTy::U8) == *cx.typeck_results().expr_ty(needle).peel_refs().kind();
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if !is_local_used(cx, needle, arg_id);
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then {
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let haystack = if let ExprKind::MethodCall(path, args, _) =
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filter_recv.kind {
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let p = path.ident.name;
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if (p == sym::iter || p == sym!(iter_mut)) && args.len() == 1 {
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&args[0]
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} else {
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filter_recv
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}
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} else {
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filter_recv
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};
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let mut applicability = Applicability::MaybeIncorrect;
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span_lint_and_sugg(
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cx,
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NAIVE_BYTECOUNT,
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expr.span,
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"you appear to be counting bytes the naive way",
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"consider using the bytecount crate",
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format!("bytecount::count({}, {})",
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snippet_with_applicability(cx, haystack.span, "..", &mut applicability),
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snippet_with_applicability(cx, needle.span, "..", &mut applicability)),
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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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