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