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|
//! Unsafety checker: every impl either implements a trait defined in this
//! crate or pertains to a type defined in this crate.
use rustc_errors::struct_span_err;
use rustc_hir as hir;
use rustc_hir::Unsafety;
use rustc_middle::ty::TyCtxt;
use rustc_span::def_id::LocalDefId;
pub(super) fn check_item(tcx: TyCtxt<'_>, def_id: LocalDefId) {
let item = tcx.hir().expect_item(def_id);
let impl_ = item.expect_impl();
if let Some(trait_ref) = tcx.impl_trait_ref(item.owner_id) {
let trait_ref = trait_ref.subst_identity();
let trait_def = tcx.trait_def(trait_ref.def_id);
let unsafe_attr =
impl_.generics.params.iter().find(|p| p.pure_wrt_drop).map(|_| "may_dangle");
match (trait_def.unsafety, unsafe_attr, impl_.unsafety, impl_.polarity) {
(Unsafety::Normal, None, Unsafety::Unsafe, hir::ImplPolarity::Positive) => {
struct_span_err!(
tcx.sess,
tcx.def_span(def_id),
E0199,
"implementing the trait `{}` is not unsafe",
trait_ref.print_only_trait_path()
)
.span_suggestion_verbose(
item.span.with_hi(item.span.lo() + rustc_span::BytePos(7)),
"remove `unsafe` from this trait implementation",
"",
rustc_errors::Applicability::MachineApplicable,
)
.emit();
}
(Unsafety::Unsafe, _, Unsafety::Normal, hir::ImplPolarity::Positive) => {
struct_span_err!(
tcx.sess,
tcx.def_span(def_id),
E0200,
"the trait `{}` requires an `unsafe impl` declaration",
trait_ref.print_only_trait_path()
)
.note(format!(
"the trait `{}` enforces invariants that the compiler can't check. \
Review the trait documentation and make sure this implementation \
upholds those invariants before adding the `unsafe` keyword",
trait_ref.print_only_trait_path()
))
.span_suggestion_verbose(
item.span.shrink_to_lo(),
"add `unsafe` to this trait implementation",
"unsafe ",
rustc_errors::Applicability::MaybeIncorrect,
)
.emit();
}
(Unsafety::Normal, Some(attr_name), Unsafety::Normal, hir::ImplPolarity::Positive) => {
struct_span_err!(
tcx.sess,
tcx.def_span(def_id),
E0569,
"requires an `unsafe impl` declaration due to `#[{}]` attribute",
attr_name
)
.note(format!(
"the trait `{}` enforces invariants that the compiler can't check. \
Review the trait documentation and make sure this implementation \
upholds those invariants before adding the `unsafe` keyword",
trait_ref.print_only_trait_path()
))
.span_suggestion_verbose(
item.span.shrink_to_lo(),
"add `unsafe` to this trait implementation",
"unsafe ",
rustc_errors::Applicability::MaybeIncorrect,
)
.emit();
}
(_, _, Unsafety::Unsafe, hir::ImplPolarity::Negative(_)) => {
// Reported in AST validation
tcx.sess.delay_span_bug(item.span, "unsafe negative impl");
}
(_, _, Unsafety::Normal, hir::ImplPolarity::Negative(_))
| (Unsafety::Unsafe, _, Unsafety::Unsafe, hir::ImplPolarity::Positive)
| (Unsafety::Normal, Some(_), Unsafety::Unsafe, hir::ImplPolarity::Positive)
| (Unsafety::Normal, None, Unsafety::Normal, _) => {
// OK
}
}
}
}
|
