bjoernager/rust
bjoernager/rust
1
Fork 0
Code Activity

Consider negative polarity on trait selection

Browse source
This commit is contained in:
Santiago Pastorino 2021-10-13 16:19:29 -03:00
parent 8b0bfb0dcb
commit ab17068662
No known key found for this signature in database
GPG key ID: 8131A24E0C79EFAF
1 changed files with 24 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

50
compiler/rustc_trait_selection/src/traits/select/mod.rs
View file

@ -1127,34 +1127,32 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
} }
// Treat negative impls as unimplemented, and reservation impls as ambiguity. // Treat negative impls as unimplemented, and reservation impls as ambiguity.
if let ImplCandidate(def_id) = candidate { if let ImplCandidate(def_id) = candidate {
match tcx.impl_polarity(def_id) { if let ty::ImplPolarity::Reservation = tcx.impl_polarity(def_id) {
ty::ImplPolarity::Negative if !self.allow_negative_impls => { if let Some(intercrate_ambiguity_clauses) = &mut self.intercrate_ambiguity_causes {
let attrs = tcx.get_attrs(def_id);
let attr = tcx.sess.find_by_name(&attrs, sym::rustc_reservation_impl);
let value = attr.and_then(|a| a.value_str());
if let Some(value) = value {
debug!(
"filter_impls: \
reservation impl ambiguity on {:?}",
def_id
);
intercrate_ambiguity_clauses.push(
IntercrateAmbiguityCause::ReservationImpl {
message: value.to_string(),
},
);
}
}
return Ok(None);
}
if !self.allow_negative_impls {
if obligation.predicate.skip_binder().polarity != tcx.impl_polarity(def_id) {
return Err(Unimplemented); return Err(Unimplemented);
} }
ty::ImplPolarity::Reservation => { }
if let Some(intercrate_ambiguity_clauses) =
&mut self.intercrate_ambiguity_causes
{
let attrs = tcx.get_attrs(def_id);
let attr = tcx.sess.find_by_name(&attrs, sym::rustc_reservation_impl);
let value = attr.and_then(|a| a.value_str());
if let Some(value) = value {
debug!(
"filter_impls: \
reservation impl ambiguity on {:?}",
def_id
);
intercrate_ambiguity_clauses.push(
IntercrateAmbiguityCause::ReservationImpl {
message: value.to_string(),
},
);
}
}
return Ok(None);
}
_ => {}
};
} }
Ok(Some(candidate)) Ok(Some(candidate))
} }