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Add consider_implied_clause
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@compiler-errors
compiler-errors committed Feb 18, 2023
1 parent 82b5205 commit 6402c98
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Showing 3 changed files with 97 additions and 102 deletions.
30 changes: 11 additions & 19 deletions compiler/rustc_trait_selection/src/solve/assembly.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -90,28 +90,20 @@ pub(super) trait GoalKind<'tcx>: TypeFoldable<'tcx> + Copy + Eq {

fn trait_def_id(self, tcx: TyCtxt<'tcx>) -> DefId;

fn consider_impl_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
impl_def_id: DefId,
) -> QueryResult<'tcx>;

// Consider a predicate we know holds (`assumption`) against a goal we're trying to prove.
fn consider_assumption(
// Consider a clause, which consists of a "assumption" and some "requirements",
// to satisfy a goal. If the requirements hold, then attempt to satisfy our
// goal by equating it with the assumption.
fn consider_implied_clause(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
assumption: ty::Predicate<'tcx>,
) -> QueryResult<'tcx> {
Self::consider_assumption_with_certainty(ecx, goal, assumption, Certainty::Yes)
}
requirements: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
) -> QueryResult<'tcx>;

// Consider a predicate we know holds (`assumption`) against a goal, unifying with
// the `assumption_certainty` if it satisfies the goal.
fn consider_assumption_with_certainty(
fn consider_impl_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
assumption: ty::Predicate<'tcx>,
assumption_certainty: Certainty,
impl_def_id: DefId,
) -> QueryResult<'tcx>;

// A type implements an `auto trait` if its components do as well. These components
Expand Down Expand Up @@ -367,7 +359,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
candidates: &mut Vec<Candidate<'tcx>>,
) {
for (i, assumption) in goal.param_env.caller_bounds().iter().enumerate() {
match G::consider_assumption(self, goal, assumption) {
match G::consider_implied_clause(self, goal, assumption, []) {
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::ParamEnv(i), result })
}
Expand Down Expand Up @@ -414,7 +406,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {

for assumption in self.tcx().item_bounds(alias_ty.def_id).subst(self.tcx(), alias_ty.substs)
{
match G::consider_assumption(self, goal, assumption) {
match G::consider_implied_clause(self, goal, assumption, []) {
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::AliasBound, result })
}
Expand Down Expand Up @@ -464,7 +456,7 @@ impl<'tcx> EvalCtxt<'_, 'tcx> {
for assumption in
elaborate_predicates(tcx, bounds.iter().map(|bound| bound.with_self_ty(tcx, self_ty)))
{
match G::consider_assumption(self, goal, assumption.predicate) {
match G::consider_implied_clause(self, goal, assumption.predicate, []) {
Ok(result) => {
candidates.push(Candidate { source: CandidateSource::BuiltinImpl, result })
}
Expand Down
117 changes: 60 additions & 57 deletions compiler/rustc_trait_selection/src/solve/project_goals.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,37 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
self.trait_def_id(tcx)
}

fn consider_implied_clause(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
assumption: ty::Predicate<'tcx>,
requirements: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
) -> QueryResult<'tcx> {
if let Some(poly_projection_pred) = assumption.to_opt_poly_projection_pred()
&& poly_projection_pred.projection_def_id() == goal.predicate.def_id()
{
ecx.infcx.probe(|_| {
let assumption_projection_pred =
ecx.infcx.instantiate_binder_with_infer(poly_projection_pred);
let mut nested_goals = ecx.infcx.eq(
goal.param_env,
goal.predicate.projection_ty,
assumption_projection_pred.projection_ty,
)?;
nested_goals.extend(requirements);
let subst_certainty = ecx.evaluate_all(nested_goals)?;

ecx.eq_term_and_make_canonical_response(
goal,
subst_certainty,
assumption_projection_pred.term,
)
})
} else {
Err(NoSolution)
}
}

fn consider_impl_candidate(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, ProjectionPredicate<'tcx>>,
Expand Down Expand Up @@ -260,36 +291,6 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
})
}

fn consider_assumption_with_certainty(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
assumption: ty::Predicate<'tcx>,
assumption_certainty: Certainty,
) -> QueryResult<'tcx> {
if let Some(poly_projection_pred) = assumption.to_opt_poly_projection_pred()
&& poly_projection_pred.projection_def_id() == goal.predicate.def_id()
{
ecx.infcx.probe(|_| {
let assumption_projection_pred =
ecx.infcx.instantiate_binder_with_infer(poly_projection_pred);
let nested_goals = ecx.infcx.eq(
goal.param_env,
goal.predicate.projection_ty,
assumption_projection_pred.projection_ty,
)?;
let subst_certainty = ecx.evaluate_all(nested_goals)?;

ecx.eq_term_and_make_canonical_response(
goal,
subst_certainty.unify_and(assumption_certainty),
assumption_projection_pred.term,
)
})
} else {
Err(NoSolution)
}
}

fn consider_auto_trait_candidate(
_ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
Expand Down Expand Up @@ -331,31 +332,27 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
goal_kind: ty::ClosureKind,
) -> QueryResult<'tcx> {
let tcx = ecx.tcx();
if let Some(tupled_inputs_and_output) =
structural_traits::extract_tupled_inputs_and_output_from_callable(
tcx,
goal.predicate.self_ty(),
goal_kind,
)?
{
// A built-in `Fn` trait needs to check that its output is `Sized`
// (FIXME: technically we only need to check this if the type is a fn ptr...)
let output_is_sized_pred = tupled_inputs_and_output
.map_bound(|(_, output)| tcx.at(DUMMY_SP).mk_trait_ref(LangItem::Sized, [output]));
let (_, output_is_sized_certainty) =
ecx.evaluate_goal(goal.with(tcx, output_is_sized_pred))?;

let pred = tupled_inputs_and_output
.map_bound(|(inputs, output)| ty::ProjectionPredicate {
projection_ty: tcx
.mk_alias_ty(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs]),
term: output.into(),
})
.to_predicate(tcx);
Self::consider_assumption_with_certainty(ecx, goal, pred, output_is_sized_certainty)
} else {
ecx.make_canonical_response(Certainty::AMBIGUOUS)
}
let Some(tupled_inputs_and_output) =
structural_traits::extract_tupled_inputs_and_output_from_callable(
tcx,
goal.predicate.self_ty(),
goal_kind,
)? else {
return ecx.make_canonical_response(Certainty::AMBIGUOUS);
};
let output_is_sized_pred = tupled_inputs_and_output
.map_bound(|(_, output)| tcx.at(DUMMY_SP).mk_trait_ref(LangItem::Sized, [output]));

let pred = tupled_inputs_and_output
.map_bound(|(inputs, output)| ty::ProjectionPredicate {
projection_ty: tcx
.mk_alias_ty(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs]),
term: output.into(),
})
.to_predicate(tcx);
// A built-in `Fn` impl only holds if the output is sized.
// (FIXME: technically we only need to check this if the type is a fn ptr...)
Self::consider_implied_clause(ecx, goal, pred, [goal.with(tcx, output_is_sized_pred)])
}

fn consider_builtin_tuple_candidate(
Expand Down Expand Up @@ -474,14 +471,17 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {

let term = substs.as_generator().return_ty().into();

Self::consider_assumption(
Self::consider_implied_clause(
ecx,
goal,
ty::Binder::dummy(ty::ProjectionPredicate {
projection_ty: ecx.tcx().mk_alias_ty(goal.predicate.def_id(), [self_ty]),
term,
})
.to_predicate(tcx),
// Technically, we need to check that the future type is Sized,
// but that's already proven by the generator being WF.
[],
)
}

Expand Down Expand Up @@ -511,7 +511,7 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
bug!("unexpected associated item `<{self_ty} as Generator>::{name}`")
};

Self::consider_assumption(
Self::consider_implied_clause(
ecx,
goal,
ty::Binder::dummy(ty::ProjectionPredicate {
Expand All @@ -521,6 +521,9 @@ impl<'tcx> assembly::GoalKind<'tcx> for ProjectionPredicate<'tcx> {
term,
})
.to_predicate(tcx),
// Technically, we need to check that the future type is Sized,
// but that's already proven by the generator being WF.
[],
)
}

Expand Down
52 changes: 26 additions & 26 deletions compiler/rustc_trait_selection/src/solve/trait_goals.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -62,11 +62,11 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
})
}

fn consider_assumption_with_certainty(
fn consider_implied_clause(
ecx: &mut EvalCtxt<'_, 'tcx>,
goal: Goal<'tcx, Self>,
assumption: ty::Predicate<'tcx>,
assumption_certainty: Certainty,
requirements: impl IntoIterator<Item = Goal<'tcx, ty::Predicate<'tcx>>>,
) -> QueryResult<'tcx> {
if let Some(poly_trait_pred) = assumption.to_opt_poly_trait_pred()
&& poly_trait_pred.def_id() == goal.predicate.def_id()
Expand All @@ -75,14 +75,13 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
ecx.infcx.probe(|_| {
let assumption_trait_pred =
ecx.infcx.instantiate_binder_with_infer(poly_trait_pred);
let nested_goals = ecx.infcx.eq(
let mut nested_goals = ecx.infcx.eq(
goal.param_env,
goal.predicate.trait_ref,
assumption_trait_pred.trait_ref,
)?;
ecx.evaluate_all(nested_goals).and_then(|certainty| {
ecx.make_canonical_response(certainty.unify_and(assumption_certainty))
})
nested_goals.extend(requirements);
ecx.evaluate_all_and_make_canonical_response(nested_goals)
})
} else {
Err(NoSolution)
Expand Down Expand Up @@ -178,29 +177,25 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
goal_kind: ty::ClosureKind,
) -> QueryResult<'tcx> {
let tcx = ecx.tcx();
if let Some(tupled_inputs_and_output) =
let Some(tupled_inputs_and_output) =
structural_traits::extract_tupled_inputs_and_output_from_callable(
tcx,
goal.predicate.self_ty(),
goal_kind,
)?
{
// A built-in `Fn` trait needs to check that its output is `Sized`
// (FIXME: technically we only need to check this if the type is a fn ptr...)
let output_is_sized_pred = tupled_inputs_and_output
.map_bound(|(_, output)| tcx.at(DUMMY_SP).mk_trait_ref(LangItem::Sized, [output]));
let (_, output_is_sized_certainty) =
ecx.evaluate_goal(goal.with(tcx, output_is_sized_pred))?;

let pred = tupled_inputs_and_output
.map_bound(|(inputs, _)| {
tcx.mk_trait_ref(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs])
})
.to_predicate(tcx);
Self::consider_assumption_with_certainty(ecx, goal, pred, output_is_sized_certainty)
} else {
ecx.make_canonical_response(Certainty::AMBIGUOUS)
}
)? else {
return ecx.make_canonical_response(Certainty::AMBIGUOUS);
};
let output_is_sized_pred = tupled_inputs_and_output
.map_bound(|(_, output)| tcx.at(DUMMY_SP).mk_trait_ref(LangItem::Sized, [output]));

let pred = tupled_inputs_and_output
.map_bound(|(inputs, _)| {
tcx.mk_trait_ref(goal.predicate.def_id(), [goal.predicate.self_ty(), inputs])
})
.to_predicate(tcx);
// A built-in `Fn` impl only holds if the output is sized.
// (FIXME: technically we only need to check this if the type is a fn ptr...)
Self::consider_implied_clause(ecx, goal, pred, [goal.with(tcx, output_is_sized_pred)])
}

fn consider_builtin_tuple_candidate(
Expand Down Expand Up @@ -236,6 +231,8 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
}

// Async generator unconditionally implement `Future`
// Technically, we need to check that the future output type is Sized,
// but that's already proven by the generator being WF.
ecx.make_canonical_response(Certainty::Yes)
}

Expand All @@ -255,13 +252,16 @@ impl<'tcx> assembly::GoalKind<'tcx> for TraitPredicate<'tcx> {
}

let generator = substs.as_generator();
Self::consider_assumption(
Self::consider_implied_clause(
ecx,
goal,
ty::Binder::dummy(
tcx.mk_trait_ref(goal.predicate.def_id(), [self_ty, generator.resume_ty()]),
)
.to_predicate(tcx),
// Technically, we need to check that the generator types are Sized,
// but that's already proven by the generator being WF.
[],
)
}

Expand Down

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