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