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Auto merge of #50250 - csmoe:wf_traitref, r=scalexm

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Chalk lowering rule: WellFormed-TraitRef

Address chalk lowering "Implemented-From-Env" as part of #49177.
r? @nikomatsakis
This commit is contained in:
bors 2018-07-09 21:01:58 +00:00
commit 9bd8458c92
5 changed files with 82 additions and 23 deletions
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96
src/librustc_traits/lowering.rs
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@ -12,8 +12,10 @@ use rustc::hir::def_id::DefId;
use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
use rustc::hir::map::definitions::DefPathData;
use rustc::hir::{self, ImplPolarity};
use rustc::traits::{Clause, Clauses, DomainGoal, Goal, PolyDomainGoal, ProgramClause,
WhereClause, FromEnv, WellFormed};
use rustc::traits::{
Clause, Clauses, DomainGoal, FromEnv, Goal, PolyDomainGoal, ProgramClause, WellFormed,
WhereClause,
};
use rustc::ty::query::Providers;
use rustc::ty::{self, Slice, TyCtxt};
use rustc_data_structures::fx::FxHashSet;
@ -101,34 +103,50 @@ impl<'tcx> Lower<PolyDomainGoal<'tcx>> for ty::Predicate<'tcx> {
Predicate::RegionOutlives(predicate) => predicate.lower(),
Predicate::TypeOutlives(predicate) => predicate.lower(),
Predicate::Projection(predicate) => predicate.lower(),
Predicate::WellFormed(ty) => ty::Binder::dummy(
DomainGoal::WellFormed(WellFormed::Ty(*ty))
),
Predicate::ObjectSafe(..) |
Predicate::ClosureKind(..) |
Predicate::Subtype(..) |
Predicate::ConstEvaluatable(..) => {
unimplemented!()
Predicate::WellFormed(ty) => {
ty::Binder::dummy(DomainGoal::WellFormed(WellFormed::Ty(*ty)))
}
Predicate::ObjectSafe(..)
| Predicate::ClosureKind(..)
| Predicate::Subtype(..)
| Predicate::ConstEvaluatable(..) => unimplemented!(),
}
}
}
/// Transforms an existing goal into a FromEnv goal.
///
/// Used for lowered where clauses (see rustc guide).
/// Used for implied bounds related rules (see rustc guide).
trait IntoFromEnvGoal {
/// Transforms an existing goal into a `FromEnv` goal.
fn into_from_env_goal(self) -> Self;
}
/// Used for well-formedness related rules (see rustc guide).
trait IntoWellFormedGoal {
/// Transforms an existing goal into a `WellFormed` goal.
fn into_well_formed_goal(self) -> Self;
}
impl<'tcx> IntoFromEnvGoal for DomainGoal<'tcx> {
fn into_from_env_goal(self) -> DomainGoal<'tcx> {
use self::WhereClause::*;
match self {
DomainGoal::Holds(Implemented(trait_ref)) => DomainGoal::FromEnv(
FromEnv::Trait(trait_ref)
),
DomainGoal::Holds(Implemented(trait_ref)) => {
DomainGoal::FromEnv(FromEnv::Trait(trait_ref))
}
other => other,
}
}
}
impl<'tcx> IntoWellFormedGoal for DomainGoal<'tcx> {
fn into_well_formed_goal(self) -> DomainGoal<'tcx> {
use self::WhereClause::*;
match self {
DomainGoal::Holds(Implemented(trait_ref)) => {
DomainGoal::WellFormed(WellFormed::Trait(trait_ref))
}
other => other,
}
}
@ -242,6 +260,8 @@ fn program_clauses_for_trait<'a, 'tcx>(
let clauses = iter::once(Clause::ForAll(ty::Binder::dummy(implemented_from_env)));
let where_clauses = &tcx.predicates_defined_on(def_id).predicates;
// Rule Implied-Bound-From-Trait
//
// For each where clause WC:
@ -252,7 +272,6 @@ fn program_clauses_for_trait<'a, 'tcx>(
// ```
// `FromEnv(WC) :- FromEnv(Self: Trait<P1..Pn>)`, for each where clause WC
let where_clauses = &tcx.predicates_defined_on(def_id).predicates;
let implied_bound_clauses = where_clauses
.into_iter()
.map(|wc| wc.lower())
@ -262,10 +281,40 @@ fn program_clauses_for_trait<'a, 'tcx>(
goal: goal.into_from_env_goal(),
hypotheses,
}))
.map(Clause::ForAll);
tcx.mk_clauses(clauses.chain(implied_bound_clauses))
// Rule WellFormed-TraitRef
//
// Here `WC` denotes the set of all where clauses:
// ```
// forall<Self, P1..Pn> {
// WellFormed(Self: Trait<P1..Pn>) :- Implemented(Self: Trait<P1..Pn>) && WellFormed(WC)
// }
// ```
// `Implemented(Self: Trait<P1..Pn>) && WellFormed(WC)`
let wf_conditions = iter::once(ty::Binder::dummy(trait_pred.lower()))
.chain(
where_clauses
.into_iter()
.map(|wc| wc.lower())
.map(|wc| wc.map_bound(|goal| goal.into_well_formed_goal()))
);
// `WellFormed(Self: Trait<P1..Pn>) :- Implemented(Self: Trait<P1..Pn>) && WellFormed(WC)`
let wf_clause = ProgramClause {
goal: DomainGoal::WellFormed(WellFormed::Trait(trait_pred)),
hypotheses: tcx.mk_goals(
wf_conditions.map(|wc| Goal::from_poly_domain_goal(wc, tcx)),
),
};
let wf_clause = iter::once(Clause::ForAll(ty::Binder::dummy(wf_clause)));
tcx.mk_clauses(
clauses
.chain(implied_bound_clauses)
.chain(wf_clause)
)
}
fn program_clauses_for_impl<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>, def_id: DefId) -> Clauses<'tcx> {
@ -307,7 +356,6 @@ pub fn program_clauses_for_type_def<'a, 'tcx>(
tcx: TyCtxt<'a, 'tcx, 'tcx>,
def_id: DefId,
) -> Clauses<'tcx> {
// Rule WellFormed-Type
//
// `struct Ty<P1..Pn> where WC1, ..., WCm`
@ -328,7 +376,10 @@ pub fn program_clauses_for_type_def<'a, 'tcx>(
let well_formed = ProgramClause {
goal: DomainGoal::WellFormed(WellFormed::Ty(ty)),
hypotheses: tcx.mk_goals(
where_clauses.iter().cloned().map(|wc| Goal::from_poly_domain_goal(wc, tcx))
where_clauses
.iter()
.cloned()
.map(|wc| Goal::from_poly_domain_goal(wc, tcx)),
),
};
@ -459,7 +510,8 @@ impl<'a, 'tcx> ClauseDumper<'a, 'tcx> {
}
if let Some(clauses) = clauses {
let mut err = self.tcx
let mut err = self
.tcx
.sess
.struct_span_err(attr.span, "program clause dump");

4
src/test/ui/chalkify/lower_env1.stderr
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@ -7,6 +7,7 @@ LL | #[rustc_dump_program_clauses] //~ ERROR program clause dump
= note: FromEnv(Self: Foo) :- FromEnv(Self: Bar).
= note: FromEnv(Self: Foo) :- FromEnv(Self: Bar).
= note: Implemented(Self: Bar) :- FromEnv(Self: Bar).
= note: WellFormed(Self: Bar) :- Implemented(Self: Bar), WellFormed(Self: Foo), WellFormed(Self: Foo).
error: program clause dump
--> $DIR/lower_env1.rs:19:1
@ -19,6 +20,9 @@ LL | #[rustc_dump_env_program_clauses] //~ ERROR program clause dump
= note: Implemented(Self: Bar) :- FromEnv(Self: Bar).
= note: Implemented(Self: Foo) :- FromEnv(Self: Foo).
= note: Implemented(Self: std::marker::Sized) :- FromEnv(Self: std::marker::Sized).
= note: WellFormed(Self: Bar) :- Implemented(Self: Bar), WellFormed(Self: Foo), WellFormed(Self: Foo).
= note: WellFormed(Self: Foo) :- Implemented(Self: Foo).
= note: WellFormed(Self: std::marker::Sized) :- Implemented(Self: std::marker::Sized).
error: aborting due to 2 previous errors

1
src/test/ui/chalkify/lower_trait.stderr
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@ -8,6 +8,7 @@ LL | #[rustc_dump_program_clauses] //~ ERROR program clause dump
= note: FromEnv(T: std::marker::Sized) :- FromEnv(Self: Foo<S, T, U>).
= note: FromEnv(U: std::marker::Sized) :- FromEnv(Self: Foo<S, T, U>).
= note: Implemented(Self: Foo<S, T, U>) :- FromEnv(Self: Foo<S, T, U>).
= note: WellFormed(Self: Foo<S, T, U>) :- Implemented(Self: Foo<S, T, U>), WellFormed(S: std::marker::Sized), WellFormed(T: std::marker::Sized), WellFormed(U: std::marker::Sized).
error: aborting due to previous error

1
src/test/ui/chalkify/lower_trait_higher_rank.stderr
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@ -8,6 +8,7 @@ LL | #[rustc_dump_program_clauses] //~ ERROR program clause dump
= note: FromEnv(F: std::ops::Fn<(&'a (u8, u16),)>) :- FromEnv(Self: Foo<F>).
= note: Implemented(Self: Foo<F>) :- FromEnv(Self: Foo<F>).
= note: ProjectionEq(<F as std::ops::FnOnce<(&'a (u8, u16),)>>::Output == &'a u8) :- FromEnv(Self: Foo<F>).
= note: WellFormed(Self: Foo<F>) :- Implemented(Self: Foo<F>), WellFormed(F: std::marker::Sized), forall<> { WellFormed(F: std::ops::Fn<(&'a (u8, u16),)>) }, forall<> { ProjectionEq(<F as std::ops::FnOnce<(&'a (u8, u16),)>>::Output == &'a u8) }.
error: aborting due to previous error

1
src/test/ui/chalkify/lower_trait_where_clause.stderr
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@ -11,6 +11,7 @@ LL | #[rustc_dump_program_clauses] //~ ERROR program clause dump
= note: Implemented(Self: Foo<'a, 'b, S, T, U>) :- FromEnv(Self: Foo<'a, 'b, S, T, U>).
= note: RegionOutlives('a : 'b) :- FromEnv(Self: Foo<'a, 'b, S, T, U>).
= note: TypeOutlives(U : 'b) :- FromEnv(Self: Foo<'a, 'b, S, T, U>).
= note: WellFormed(Self: Foo<'a, 'b, S, T, U>) :- Implemented(Self: Foo<'a, 'b, S, T, U>), WellFormed(S: std::marker::Sized), WellFormed(T: std::marker::Sized), WellFormed(S: std::fmt::Debug), WellFormed(T: std::borrow::Borrow<U>), RegionOutlives('a : 'b), TypeOutlives(U : 'b).
error: aborting due to previous error