3 use rustc_errors::Applicability;
4 use rustc_hir::{Expr, ExprKind, Mutability, TyKind};
5 use rustc_lint::LateContext;
6 use rustc_middle::ty::{self, TypeAndMut};
7 use rustc_semver::RustcVersion;
9 use if_chain::if_chain;
11 use crate::utils::sugg::Sugg;
12 use crate::utils::{meets_msrv, span_lint_and_sugg};
14 use super::PTR_AS_PTR;
16 const PTR_AS_PTR_MSRV: RustcVersion = RustcVersion::new(1, 38, 0);
18 pub(super) fn check(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, msrv: &Option<RustcVersion>) {
19 if !meets_msrv(msrv.as_ref(), &PTR_AS_PTR_MSRV) {
24 if let ExprKind::Cast(cast_expr, cast_to_hir_ty) = expr.kind;
25 let (cast_from, cast_to) = (cx.typeck_results().expr_ty(cast_expr), cx.typeck_results().expr_ty(expr));
26 if let ty::RawPtr(TypeAndMut { mutbl: from_mutbl, .. }) = cast_from.kind();
27 if let ty::RawPtr(TypeAndMut { ty: to_pointee_ty, mutbl: to_mutbl }) = cast_to.kind();
28 if matches!((from_mutbl, to_mutbl),
29 (Mutability::Not, Mutability::Not) | (Mutability::Mut, Mutability::Mut));
30 // The `U` in `pointer::cast` have to be `Sized`
31 // as explained here: https://github.com/rust-lang/rust/issues/60602.
32 if to_pointee_ty.is_sized(cx.tcx.at(expr.span), cx.param_env);
34 let mut applicability = Applicability::MachineApplicable;
35 let cast_expr_sugg = Sugg::hir_with_applicability(cx, cast_expr, "_", &mut applicability);
36 let turbofish = match &cast_to_hir_ty.kind {
37 TyKind::Infer => Cow::Borrowed(""),
38 TyKind::Ptr(mut_ty) if matches!(mut_ty.ty.kind, TyKind::Infer) => Cow::Borrowed(""),
39 _ => Cow::Owned(format!("::<{}>", to_pointee_ty)),
45 "`as` casting between raw pointers without changing its mutability",
46 "try `pointer::cast`, a safer alternative",
47 format!("{}.cast{}()", cast_expr_sugg.maybe_par(), turbofish),