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use super::TRANSMUTE_PTR_TO_REF;
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::msrvs::{self, Msrv};
use clippy_utils::source::snippet_with_applicability;
use clippy_utils::sugg;
use rustc_errors::Applicability;
use rustc_hir::{self as hir, Expr, GenericArg, Mutability, Path, TyKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, Ty, TypeVisitable};
/// Checks for `transmute_ptr_to_ref` lint.
/// Returns `true` if it's triggered, otherwise returns `false`.
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
e: &'tcx Expr<'_>,
from_ty: Ty<'tcx>,
to_ty: Ty<'tcx>,
arg: &'tcx Expr<'_>,
path: &'tcx Path<'_>,
msrv: &Msrv,
) -> bool {
match (&from_ty.kind(), &to_ty.kind()) {
(ty::RawPtr(from_ptr_ty), ty::Ref(_, to_ref_ty, mutbl)) => {
span_lint_and_then(
cx,
TRANSMUTE_PTR_TO_REF,
e.span,
&format!("transmute from a pointer type (`{from_ty}`) to a reference type (`{to_ty}`)"),
|diag| {
let arg = sugg::Sugg::hir(cx, arg, "..");
let (deref, cast) = if *mutbl == Mutability::Mut {
("&mut *", "*mut")
} else {
("&*", "*const")
};
let mut app = Applicability::MachineApplicable;
let sugg = if let Some(ty) = get_explicit_type(path) {
let ty_snip = snippet_with_applicability(cx, ty.span, "..", &mut app);
if msrv.meets(msrvs::POINTER_CAST) {
format!("{deref}{}.cast::<{ty_snip}>()", arg.maybe_par())
} else if from_ptr_ty.has_erased_regions() {
sugg::make_unop(deref, arg.as_ty(format!("{cast} () as {cast} {ty_snip}"))).to_string()
} else {
sugg::make_unop(deref, arg.as_ty(format!("{cast} {ty_snip}"))).to_string()
}
} else if from_ptr_ty.ty == *to_ref_ty {
if from_ptr_ty.has_erased_regions() {
if msrv.meets(msrvs::POINTER_CAST) {
format!("{deref}{}.cast::<{to_ref_ty}>()", arg.maybe_par())
} else {
sugg::make_unop(deref, arg.as_ty(format!("{cast} () as {cast} {to_ref_ty}")))
.to_string()
}
} else {
sugg::make_unop(deref, arg).to_string()
}
} else {
sugg::make_unop(deref, arg.as_ty(format!("{cast} {to_ref_ty}"))).to_string()
};
diag.span_suggestion(e.span, "try", sugg, app);
},
);
true
},
_ => false,
}
}
/// Gets the type `Bar` in `…::transmute<Foo, &Bar>`.
fn get_explicit_type<'tcx>(path: &'tcx Path<'tcx>) -> Option<&'tcx hir::Ty<'tcx>> {
if let GenericArg::Type(ty) = path.segments.last()?.args?.args.get(1)?
&& let TyKind::Ref(_, ty) = &ty.kind
{
Some(ty.ty)
} else {
None
}
}
|
