3 use clippy_utils::diagnostics::span_lint_and_sugg;
4 use clippy_utils::msrvs::{self, Msrv};
5 use clippy_utils::sugg::Sugg;
6 use if_chain::if_chain;
7 use rustc_errors::Applicability;
8 use rustc_hir::{Expr, ExprKind, Mutability, TyKind};
9 use rustc_lint::LateContext;
10 use rustc_middle::ty::{self, TypeAndMut};
12 use super::PTR_AS_PTR;
14 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, msrv: &Msrv) {
15 if !msrv.meets(msrvs::POINTER_CAST) {
20 if let ExprKind::Cast(cast_expr, cast_to_hir_ty) = expr.kind;
21 let (cast_from, cast_to) = (cx.typeck_results().expr_ty(cast_expr), cx.typeck_results().expr_ty(expr));
22 if let ty::RawPtr(TypeAndMut { mutbl: from_mutbl, .. }) = cast_from.kind();
23 if let ty::RawPtr(TypeAndMut { ty: to_pointee_ty, mutbl: to_mutbl }) = cast_to.kind();
24 if matches!((from_mutbl, to_mutbl),
25 (Mutability::Not, Mutability::Not) | (Mutability::Mut, Mutability::Mut));
26 // The `U` in `pointer::cast` have to be `Sized`
27 // as explained here: https://github.com/rust-lang/rust/issues/60602.
28 if to_pointee_ty.is_sized(cx.tcx, cx.param_env);
30 let mut applicability = Applicability::MachineApplicable;
31 let cast_expr_sugg = Sugg::hir_with_applicability(cx, cast_expr, "_", &mut applicability);
32 let turbofish = match &cast_to_hir_ty.kind {
33 TyKind::Infer => Cow::Borrowed(""),
34 TyKind::Ptr(mut_ty) if matches!(mut_ty.ty.kind, TyKind::Infer) => Cow::Borrowed(""),
35 _ => Cow::Owned(format!("::<{to_pointee_ty}>")),
41 "`as` casting between raw pointers without changing its mutability",
42 "try `pointer::cast`, a safer alternative",
43 format!("{}.cast{turbofish}()", cast_expr_sugg.maybe_par()),