bjoernager/rust
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Explicitly reject negative and reservation drop impls

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This commit is contained in:
Michael Goulet 2023-04-26 18:22:32 +00:00
parent 6ce22733b9
commit bd146c72ac
10 changed files with 74 additions and 28 deletions
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17
compiler/rustc_hir_analysis/src/check/dropck.rs
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@ -1,7 +1,6 @@
// FIXME(@lcnr): Move this module out of `rustc_hir_analysis`.
//
// We don't do any drop checking during hir typeck.
use crate::hir::def_id::{DefId, LocalDefId};
use rustc_errors::{struct_span_err, ErrorGuaranteed};
use rustc_middle::ty::error::TypeError;
use rustc_middle::ty::relate::{Relate, RelateResult, TypeRelation};
@ -9,6 +8,9 @@ use rustc_middle::ty::subst::SubstsRef;
use rustc_middle::ty::util::IgnoreRegions;
use rustc_middle::ty::{self, Predicate, Ty, TyCtxt};
use crate::errors;
use crate::hir::def_id::{DefId, LocalDefId};
/// This function confirms that the `Drop` implementation identified by
/// `drop_impl_did` is not any more specialized than the type it is
/// attached to (Issue #8142).
@ -27,6 +29,19 @@ use rustc_middle::ty::{self, Predicate, Ty, TyCtxt};
/// cannot do `struct S<T>; impl<T:Clone> Drop for S<T> { ... }`).
///
pub fn check_drop_impl(tcx: TyCtxt<'_>, drop_impl_did: DefId) -> Result<(), ErrorGuaranteed> {
match tcx.impl_polarity(drop_impl_did) {
ty::ImplPolarity::Positive => {}
ty::ImplPolarity::Negative => {
return Err(tcx.sess.emit_err(errors::DropImplPolarity::Negative {
span: tcx.def_span(drop_impl_did),
}));
}
ty::ImplPolarity::Reservation => {
return Err(tcx.sess.emit_err(errors::DropImplPolarity::Reservation {
span: tcx.def_span(drop_impl_did),
}));
}
}
let dtor_self_type = tcx.type_of(drop_impl_did).subst_identity();
let dtor_predicates = tcx.predicates_of(drop_impl_did);
match dtor_self_type.kind() {