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Only assemble_candidates_from_impls for polarity Negative

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Santiago Pastorino 2021-10-14 16:15:44 -03:00
parent 511076a102
commit da8873e343
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7 changed files with 75 additions and 80 deletions
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120
compiler/rustc_trait_selection/src/traits/select/candidate_assembly.rs
View File

@ -254,68 +254,72 @@ pub(super) fn assemble_candidates<'o>(
let mut candidates = SelectionCandidateSet { vec: Vec::new(), ambiguous: false };
self.assemble_candidates_for_trait_alias(obligation, &mut candidates);
// Other bounds. Consider both in-scope bounds from fn decl
// and applicable impls. There is a certain set of precedence rules here.
let def_id = obligation.predicate.def_id();
let lang_items = self.tcx().lang_items();
if lang_items.copy_trait() == Some(def_id) {
debug!(obligation_self_ty = ?obligation.predicate.skip_binder().self_ty());
// User-defined copy impls are permitted, but only for
// structs and enums.
if obligation.predicate.skip_binder().polarity == ty::ImplPolarity::Negative {
self.assemble_candidates_from_impls(obligation, &mut candidates);
// For other types, we'll use the builtin rules.
let copy_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(copy_conditions, &mut candidates);
} else if lang_items.discriminant_kind_trait() == Some(def_id) {
// `DiscriminantKind` is automatically implemented for every type.
candidates.vec.push(DiscriminantKindCandidate);
} else if lang_items.pointee_trait() == Some(def_id) {
// `Pointee` is automatically implemented for every type.
candidates.vec.push(PointeeCandidate);
} else if lang_items.sized_trait() == Some(def_id) {
// Sized is never implementable by end-users, it is
// always automatically computed.
let sized_conditions = self.sized_conditions(obligation);
self.assemble_builtin_bound_candidates(sized_conditions, &mut candidates);
} else if lang_items.unsize_trait() == Some(def_id) {
self.assemble_candidates_for_unsizing(obligation, &mut candidates);
} else if lang_items.drop_trait() == Some(def_id)
&& obligation.predicate.skip_binder().constness == ty::BoundConstness::ConstIfConst
{
if self.is_in_const_context {
self.assemble_const_drop_candidates(obligation, &mut candidates)?;
} else {
debug!("passing ~const Drop bound; in non-const context");
// `~const Drop` when we are not in a const context has no effect.
candidates.vec.push(ConstDropCandidate)
}
} else {
if lang_items.clone_trait() == Some(def_id) {
// Same builtin conditions as `Copy`, i.e., every type which has builtin support
// for `Copy` also has builtin support for `Clone`, and tuples/arrays of `Clone`
// types have builtin support for `Clone`.
let clone_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(clone_conditions, &mut candidates);
self.assemble_candidates_for_trait_alias(obligation, &mut candidates);
// Other bounds. Consider both in-scope bounds from fn decl
// and applicable impls. There is a certain set of precedence rules here.
let def_id = obligation.predicate.def_id();
let lang_items = self.tcx().lang_items();
if lang_items.copy_trait() == Some(def_id) {
debug!(obligation_self_ty = ?obligation.predicate.skip_binder().self_ty());
// User-defined copy impls are permitted, but only for
// structs and enums.
self.assemble_candidates_from_impls(obligation, &mut candidates);
// For other types, we'll use the builtin rules.
let copy_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(copy_conditions, &mut candidates);
} else if lang_items.discriminant_kind_trait() == Some(def_id) {
// `DiscriminantKind` is automatically implemented for every type.
candidates.vec.push(DiscriminantKindCandidate);
} else if lang_items.pointee_trait() == Some(def_id) {
// `Pointee` is automatically implemented for every type.
candidates.vec.push(PointeeCandidate);
} else if lang_items.sized_trait() == Some(def_id) {
// Sized is never implementable by end-users, it is
// always automatically computed.
let sized_conditions = self.sized_conditions(obligation);
self.assemble_builtin_bound_candidates(sized_conditions, &mut candidates);
} else if lang_items.unsize_trait() == Some(def_id) {
self.assemble_candidates_for_unsizing(obligation, &mut candidates);
} else if lang_items.drop_trait() == Some(def_id)
&& obligation.predicate.skip_binder().constness == ty::BoundConstness::ConstIfConst
{
if self.is_in_const_context {
self.assemble_const_drop_candidates(obligation, &mut candidates)?;
} else {
debug!("passing ~const Drop bound; in non-const context");
// `~const Drop` when we are not in a const context has no effect.
candidates.vec.push(ConstDropCandidate)
}
} else {
if lang_items.clone_trait() == Some(def_id) {
// Same builtin conditions as `Copy`, i.e., every type which has builtin support
// for `Copy` also has builtin support for `Clone`, and tuples/arrays of `Clone`
// types have builtin support for `Clone`.
let clone_conditions = self.copy_clone_conditions(obligation);
self.assemble_builtin_bound_candidates(clone_conditions, &mut candidates);
}
self.assemble_generator_candidates(obligation, &mut candidates);
self.assemble_closure_candidates(obligation, &mut candidates);
self.assemble_fn_pointer_candidates(obligation, &mut candidates);
self.assemble_candidates_from_impls(obligation, &mut candidates);
self.assemble_candidates_from_object_ty(obligation, &mut candidates);
}
self.assemble_generator_candidates(obligation, &mut candidates);
self.assemble_closure_candidates(obligation, &mut candidates);
self.assemble_fn_pointer_candidates(obligation, &mut candidates);
self.assemble_candidates_from_impls(obligation, &mut candidates);
self.assemble_candidates_from_object_ty(obligation, &mut candidates);
}
self.assemble_candidates_from_projected_tys(obligation, &mut candidates);
self.assemble_candidates_from_caller_bounds(stack, &mut candidates)?;
// Auto implementations have lower priority, so we only
// consider triggering a default if there is no other impl that can apply.
if candidates.vec.is_empty() {
self.assemble_candidates_from_auto_impls(obligation, &mut candidates);
self.assemble_candidates_from_projected_tys(obligation, &mut candidates);
self.assemble_candidates_from_caller_bounds(stack, &mut candidates)?;
// Auto implementations have lower priority, so we only
// consider triggering a default if there is no other impl that can apply.
if candidates.vec.is_empty() {
self.assemble_candidates_from_auto_impls(obligation, &mut candidates);
}
}
debug!("candidate list size: {}", candidates.vec.len());
Ok(candidates)

2
src/test/ui/traits/cache-reached-depth-ice.rs
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@ -41,5 +41,5 @@ fn test<X: ?Sized + Send>() {}
fn main() {
test::<A>();
//~^ ERROR evaluate(Binder(TraitPredicate(<A as std::marker::Send>), [])) = Ok(EvaluatedToOk)
//~^ ERROR evaluate(Binder(TraitPredicate(<A as std::marker::Send>, polarity:Positive), [])) = Ok(EvaluatedToOk)
}

2
src/test/ui/traits/cache-reached-depth-ice.stderr
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@ -1,4 +1,4 @@
error: evaluate(Binder(TraitPredicate(<A as std::marker::Send>), [])) = Ok(EvaluatedToOk)
error: evaluate(Binder(TraitPredicate(<A as std::marker::Send>, polarity:Positive), [])) = Ok(EvaluatedToOk)
--> $DIR/cache-reached-depth-ice.rs:43:5
|
LL | fn test<X: ?Sized + Send>() {}

8
src/test/ui/traits/issue-83538-tainted-cache-after-cycle.rs
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@ -57,10 +57,10 @@ fn main() {
// Key is that Vec<First> is "ok" and Third<'_, Ty> is "ok modulo regions":
forward();
//~^ ERROR evaluate(Binder(TraitPredicate(<std::vec::Vec<First> as std::marker::Unpin>), [])) = Ok(EvaluatedToOk)
//~| ERROR evaluate(Binder(TraitPredicate(<Third<'_, Ty> as std::marker::Unpin>), [])) = Ok(EvaluatedToOkModuloRegions)
//~^ ERROR evaluate(Binder(TraitPredicate(<std::vec::Vec<First> as std::marker::Unpin>, polarity:Positive), [])) = Ok(EvaluatedToOk)
//~| ERROR evaluate(Binder(TraitPredicate(<Third<'_, Ty> as std::marker::Unpin>, polarity:Positive), [])) = Ok(EvaluatedToOkModuloRegions)
reverse();
//~^ ERROR evaluate(Binder(TraitPredicate(<std::vec::Vec<First> as std::marker::Unpin>), [])) = Ok(EvaluatedToOk)
//~| ERROR evaluate(Binder(TraitPredicate(<Third<'_, Ty> as std::marker::Unpin>), [])) = Ok(EvaluatedToOkModuloRegions)
//~^ ERROR evaluate(Binder(TraitPredicate(<std::vec::Vec<First> as std::marker::Unpin>, polarity:Positive), [])) = Ok(EvaluatedToOk)
//~| ERROR evaluate(Binder(TraitPredicate(<Third<'_, Ty> as std::marker::Unpin>, polarity:Positive), [])) = Ok(EvaluatedToOkModuloRegions)
}

8
src/test/ui/traits/issue-83538-tainted-cache-after-cycle.stderr
View File

@ -1,4 +1,4 @@
error: evaluate(Binder(TraitPredicate(<std::vec::Vec<First> as std::marker::Unpin>), [])) = Ok(EvaluatedToOk)
error: evaluate(Binder(TraitPredicate(<std::vec::Vec<First> as std::marker::Unpin>, polarity:Positive), [])) = Ok(EvaluatedToOk)
--> $DIR/issue-83538-tainted-cache-after-cycle.rs:59:5
|
LL | Vec<First>: Unpin,
@ -7,7 +7,7 @@ LL | Vec<First>: Unpin,
LL | forward();
| ^^^^^^^
error: evaluate(Binder(TraitPredicate(<Third<'_, Ty> as std::marker::Unpin>), [])) = Ok(EvaluatedToOkModuloRegions)
error: evaluate(Binder(TraitPredicate(<Third<'_, Ty> as std::marker::Unpin>, polarity:Positive), [])) = Ok(EvaluatedToOkModuloRegions)
--> $DIR/issue-83538-tainted-cache-after-cycle.rs:59:5
|
LL | Third<'a, Ty>: Unpin,
@ -16,7 +16,7 @@ LL | Third<'a, Ty>: Unpin,
LL | forward();
| ^^^^^^^
error: evaluate(Binder(TraitPredicate(<Third<'_, Ty> as std::marker::Unpin>), [])) = Ok(EvaluatedToOkModuloRegions)
error: evaluate(Binder(TraitPredicate(<Third<'_, Ty> as std::marker::Unpin>, polarity:Positive), [])) = Ok(EvaluatedToOkModuloRegions)
--> $DIR/issue-83538-tainted-cache-after-cycle.rs:63:5
|
LL | Third<'a, Ty>: Unpin,
@ -25,7 +25,7 @@ LL | Third<'a, Ty>: Unpin,
LL | reverse();
| ^^^^^^^
error: evaluate(Binder(TraitPredicate(<std::vec::Vec<First> as std::marker::Unpin>), [])) = Ok(EvaluatedToOk)
error: evaluate(Binder(TraitPredicate(<std::vec::Vec<First> as std::marker::Unpin>, polarity:Positive), [])) = Ok(EvaluatedToOk)
--> $DIR/issue-83538-tainted-cache-after-cycle.rs:63:5
|
LL | Vec<First>: Unpin,

4
src/test/ui/traits/negative-impls/rely-on-negative-impl-in-coherence.rs
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@ -1,3 +1,5 @@
// check-pass
#![feature(negative_impls)]
// aux-build: foreign_trait.rs
@ -16,6 +18,6 @@
trait LocalTrait { }
impl<T: ForeignTrait> LocalTrait for T { }
impl LocalTrait for String { } //~ ERROR conflicting implementations
impl LocalTrait for String { }
fn main() { }

11
src/test/ui/traits/negative-impls/rely-on-negative-impl-in-coherence.stderr
View File

@ -1,11 +0,0 @@
error[E0119]: conflicting implementations of trait `LocalTrait` for type `std::string::String`
--> $DIR/rely-on-negative-impl-in-coherence.rs:19:1
|
LL | impl<T: ForeignTrait> LocalTrait for T { }
| -------------------------------------- first implementation here
LL | impl LocalTrait for String { }
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `std::string::String`
error: aborting due to previous error
For more information about this error, try `rustc --explain E0119`.