1 use if_chain::if_chain;
2 use rustc_errors::Applicability;
3 use rustc_hir::{Expr, ExprKind, LangItem};
4 use rustc_lint::{LateContext, LateLintPass, LintContext};
5 use rustc_middle::{lint::in_external_macro, ty::TyS};
6 use rustc_session::{declare_lint_pass, declare_tool_lint};
8 use crate::utils::{is_type_lang_item, snippet_with_applicability, span_lint_and_sugg};
10 declare_clippy_lint! {
11 /// **What it does:** Checks for redundant slicing expressions which use the full range, and
12 /// do not change the type.
14 /// **Why is this bad?** It unnecessarily adds complexity to the expression.
16 /// **Known problems:** If the type being sliced has an implementation of `Index<RangeFull>`
17 /// that actually changes anything then it can't be removed. However, this would be surprising
18 /// to people reading the code and should have a note with it.
23 /// fn get_slice(x: &[u32]) -> &[u32] {
29 /// fn get_slice(x: &[u32]) -> &[u32] {
33 pub REDUNDANT_SLICING,
35 "redundant slicing of the whole range of a type"
38 declare_lint_pass!(RedundantSlicing => [REDUNDANT_SLICING]);
40 impl LateLintPass<'_> for RedundantSlicing {
41 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
42 if in_external_macro(cx.sess(), expr.span) {
47 if let ExprKind::AddrOf(_, _, addressee) = expr.kind;
48 if let ExprKind::Index(indexed, range) = addressee.kind;
49 if is_type_lang_item(cx, cx.typeck_results().expr_ty_adjusted(range), LangItem::RangeFull);
50 if TyS::same_type(cx.typeck_results().expr_ty(expr), cx.typeck_results().expr_ty(indexed));
52 let mut app = Applicability::MachineApplicable;
53 let hint = snippet_with_applicability(cx, indexed.span, "..", &mut app).into_owned();
59 "redundant slicing of the whole range",
60 "use the original slice instead",