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Higher ranked goal source, do overflow handling less badly

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This commit is contained in:
Michael Goulet 2024-05-02 13:51:13 -04:00
parent 3e03b1b190
commit 34e91ece90
15 changed files with 163 additions and 144 deletions
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2
compiler/rustc_middle/src/traits/solve.rs
View File

@ -273,6 +273,8 @@ pub enum GoalSource {
/// they are from an impl where-clause. This is necessary due to
/// backwards compatability, cc trait-system-refactor-initiatitive#70.
ImplWhereBound,
/// Instantiating a higher-ranked goal and re-proving it.
InstantiateHigherRanked,
}
/// Possible ways the given goal can be proven.

1
compiler/rustc_middle/src/traits/solve/inspect/format.rs
View File

@ -127,6 +127,7 @@ pub(super) fn format_probe(&mut self, probe: &Probe<'_>) -> std::fmt::Result {
let source = match source {
GoalSource::Misc => "misc",
GoalSource::ImplWhereBound => "impl where-bound",
GoalSource::InstantiateHigherRanked => "higher-ranked goal",
};
writeln!(this.f, "ADDED GOAL ({source}): {goal:?}")?
}

2
compiler/rustc_trait_selection/src/solve/eval_ctxt/mod.rs
View File

@ -454,7 +454,7 @@ fn compute_goal(&mut self, goal: Goal<'tcx, ty::Predicate<'tcx>>) -> QueryResult
} else {
self.infcx.enter_forall(kind, |kind| {
let goal = goal.with(self.tcx(), ty::Binder::dummy(kind));
self.add_goal(GoalSource::ImplWhereBound, goal);
self.add_goal(GoalSource::InstantiateHigherRanked, goal);
self.evaluate_added_goals_and_make_canonical_response(Certainty::Yes)
})
}

151
compiler/rustc_trait_selection/src/solve/fulfill.rs
View File

@ -7,10 +7,10 @@
use rustc_infer::traits::solve::{CandidateSource, GoalSource, MaybeCause};
use rustc_infer::traits::{
self, FulfillmentError, FulfillmentErrorCode, MismatchedProjectionTypes, Obligation,
PredicateObligation, SelectionError, TraitEngine,
ObligationCause, PredicateObligation, SelectionError, TraitEngine,
};
use rustc_middle::ty;
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::{self, TyCtxt};
use super::eval_ctxt::GenerateProofTree;
use super::inspect::{ProofTreeInferCtxtExt, ProofTreeVisitor};
@ -219,14 +219,14 @@ fn fulfillment_error_for_no_solution<'tcx>(
}
ty::PredicateKind::Subtype(pred) => {
let (a, b) = infcx.enter_forall_and_leak_universe(
root_obligation.predicate.kind().rebind((pred.a, pred.b)),
obligation.predicate.kind().rebind((pred.a, pred.b)),
);
let expected_found = ExpectedFound::new(true, a, b);
FulfillmentErrorCode::SubtypeError(expected_found, TypeError::Sorts(expected_found))
}
ty::PredicateKind::Coerce(pred) => {
let (a, b) = infcx.enter_forall_and_leak_universe(
root_obligation.predicate.kind().rebind((pred.a, pred.b)),
obligation.predicate.kind().rebind((pred.a, pred.b)),
);
let expected_found = ExpectedFound::new(false, a, b);
FulfillmentErrorCode::SubtypeError(expected_found, TypeError::Sorts(expected_found))
@ -272,6 +272,20 @@ fn fulfillment_error_for_stalled<'tcx>(
}
}
fn find_best_leaf_obligation<'tcx>(
infcx: &InferCtxt<'tcx>,
obligation: &PredicateObligation<'tcx>,
) -> PredicateObligation<'tcx> {
let obligation = infcx.resolve_vars_if_possible(obligation.clone());
infcx
.visit_proof_tree(
obligation.clone().into(),
&mut BestObligation { obligation: obligation.clone() },
)
.break_value()
.unwrap_or(obligation)
}
struct BestObligation<'tcx> {
obligation: PredicateObligation<'tcx>,
}
@ -279,10 +293,9 @@ struct BestObligation<'tcx> {
impl<'tcx> BestObligation<'tcx> {
fn with_derived_obligation(
&mut self,
derive_obligation: impl FnOnce(&mut Self) -> PredicateObligation<'tcx>,
derived_obligation: PredicateObligation<'tcx>,
and_then: impl FnOnce(&mut Self) -> <Self as ProofTreeVisitor<'tcx>>::Result,
) -> <Self as ProofTreeVisitor<'tcx>>::Result {
let derived_obligation = derive_obligation(self);
let old_obligation = std::mem::replace(&mut self.obligation, derived_obligation);
let res = and_then(self);
self.obligation = old_obligation;
@ -298,13 +311,10 @@ fn span(&self) -> rustc_span::Span {
}
fn visit_goal(&mut self, goal: &super::inspect::InspectGoal<'_, 'tcx>) -> Self::Result {
// FIXME: Throw out candidates that have no failing WC and >0 failing misc goal.
// This most likely means that the goal just didn't unify at all, e.g. a param
// candidate with an alias in it.
let candidates = goal.candidates();
// FIXME: Throw out candidates that have no failing WC and >1 failing misc goal.
// HACK:
if self.obligation.recursion_depth > 3 {
return ControlFlow::Break(self.obligation.clone());
}
let [candidate] = candidates.as_slice() else {
return ControlFlow::Break(self.obligation.clone());
@ -320,80 +330,71 @@ fn visit_goal(&mut self, goal: &super::inspect::InspectGoal<'_, 'tcx>) -> Self::
let tcx = goal.infcx().tcx;
let mut impl_where_bound_count = 0;
for nested_goal in candidate.instantiate_nested_goals(self.span()) {
if matches!(nested_goal.source(), GoalSource::ImplWhereBound) {
impl_where_bound_count += 1;
} else {
continue;
let obligation;
match nested_goal.source() {
GoalSource::Misc => {
continue;
}
GoalSource::ImplWhereBound => {
obligation = Obligation {
cause: derive_cause(
tcx,
candidate.kind(),
self.obligation.cause.clone(),
impl_where_bound_count,
parent_trait_pred,
),
param_env: nested_goal.goal().param_env,
predicate: nested_goal.goal().predicate,
recursion_depth: self.obligation.recursion_depth + 1,
};
impl_where_bound_count += 1;
}
GoalSource::InstantiateHigherRanked => {
obligation = self.obligation.clone();
}
}
// Skip nested goals that hold.
//FIXME: We should change the max allowed certainty based on if we're
// visiting an ambiguity or error obligation.
if matches!(nested_goal.result(), Ok(Certainty::Yes)) {
continue;
}
self.with_derived_obligation(
|self_| {
let mut cause = self_.obligation.cause.clone();
cause = match candidate.kind() {
ProbeKind::TraitCandidate {
source: CandidateSource::Impl(impl_def_id),
result: _,
} => {
let idx = impl_where_bound_count - 1;
if let Some((_, span)) = tcx
.predicates_of(impl_def_id)
.instantiate_identity(tcx)
.iter()
.nth(idx)
{
cause.derived_cause(parent_trait_pred, |derived| {
traits::ImplDerivedObligation(Box::new(
traits::ImplDerivedObligationCause {
derived,
impl_or_alias_def_id: impl_def_id,
impl_def_predicate_index: Some(idx),
span,
},
))
})
} else {
cause
}
}
ProbeKind::TraitCandidate {
source: CandidateSource::BuiltinImpl(..),
result: _,
} => {
cause.derived_cause(parent_trait_pred, traits::BuiltinDerivedObligation)
}
_ => cause,
};
Obligation {
cause,
param_env: nested_goal.goal().param_env,
predicate: nested_goal.goal().predicate,
recursion_depth: self_.obligation.recursion_depth + 1,
}
},
|self_| self_.visit_goal(&nested_goal),
)?;
self.with_derived_obligation(obligation, |this| nested_goal.visit_with(this))?;
}
ControlFlow::Break(self.obligation.clone())
}
}
fn find_best_leaf_obligation<'tcx>(
infcx: &InferCtxt<'tcx>,
obligation: &PredicateObligation<'tcx>,
) -> PredicateObligation<'tcx> {
let obligation = infcx.resolve_vars_if_possible(obligation.clone());
infcx
.visit_proof_tree(
obligation.clone().into(),
&mut BestObligation { obligation: obligation.clone() },
)
.break_value()
.unwrap_or(obligation)
fn derive_cause<'tcx>(
tcx: TyCtxt<'tcx>,
candidate_kind: ProbeKind<'tcx>,
mut cause: ObligationCause<'tcx>,
idx: usize,
parent_trait_pred: ty::PolyTraitPredicate<'tcx>,
) -> ObligationCause<'tcx> {
match candidate_kind {
ProbeKind::TraitCandidate { source: CandidateSource::Impl(impl_def_id), result: _ } => {
if let Some((_, span)) =
tcx.predicates_of(impl_def_id).instantiate_identity(tcx).iter().nth(idx)
{
cause = cause.derived_cause(parent_trait_pred, |derived| {
traits::ImplDerivedObligation(Box::new(traits::ImplDerivedObligationCause {
derived,
impl_or_alias_def_id: impl_def_id,
impl_def_predicate_index: Some(idx),
span,
}))
})
}
}
ProbeKind::TraitCandidate { source: CandidateSource::BuiltinImpl(..), result: _ } => {
cause = cause.derived_cause(parent_trait_pred, traits::BuiltinDerivedObligation);
}
_ => {}
};
cause
}

14
compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
View File

@ -128,10 +128,8 @@ pub fn shallow_certainty(&self) -> Certainty {
/// back their inference constraints. This function modifies
/// the state of the `infcx`.
pub fn visit_nested_no_probe<V: ProofTreeVisitor<'tcx>>(&self, visitor: &mut V) -> V::Result {
if self.goal.depth < visitor.config().max_depth {
for goal in self.instantiate_nested_goals(visitor.span()) {
try_visit!(visitor.visit_goal(&goal));
}
for goal in self.instantiate_nested_goals(visitor.span()) {
try_visit!(goal.visit_with(visitor));
}
V::Result::output()
@ -360,6 +358,14 @@ fn new(
source,
}
}
pub(crate) fn visit_with<V: ProofTreeVisitor<'tcx>>(&self, visitor: &mut V) -> V::Result {
if self.depth < visitor.config().max_depth {
try_visit!(visitor.visit_goal(self));
}
V::Result::output()
}
}
/// The public API to interact with proof trees.

2
tests/ui/traits/next-solver/coherence/coherence-fulfill-overflow.stderr
View File

@ -6,7 +6,7 @@ LL | impl<T: ?Sized + TwoW> Trait for W<T> {}
LL | impl<T: ?Sized + TwoW> Trait for T {}
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<W<_>>>>>>>>>>>>>>>>>>>>>>`
|
= note: overflow evaluating the requirement `W<W<W<W<W<W<W<W<W<W<W<W<W<W<_>>>>>>>>>>>>>>: TwoW`
= note: overflow evaluating the requirement `W<W<W<W<_>>>>: TwoW`
= help: consider increasing the recursion limit by adding a `#![recursion_limit = "20"]` attribute to your crate (`coherence_fulfill_overflow`)
error: aborting due to 1 previous error

36
tests/ui/traits/next-solver/cycles/double-cycle-inductive-coinductive.stderr
View File

@ -1,16 +1,9 @@
error[E0275]: overflow evaluating the requirement `(): Trait`
error[E0275]: overflow evaluating the requirement `(): Inductive`
--> $DIR/double-cycle-inductive-coinductive.rs:32:19
|
LL | impls_trait::<()>();
| ^^
|
note: required for `()` to implement `Inductive`
--> $DIR/double-cycle-inductive-coinductive.rs:12:16
|
LL | impl<T: Trait> Inductive for T {}
| ----- ^^^^^^^^^ ^
| |
| unsatisfied trait bound introduced here
note: required for `()` to implement `Trait`
--> $DIR/double-cycle-inductive-coinductive.rs:9:34
|
@ -18,7 +11,14 @@ LL | impl<T: Inductive + Coinductive> Trait for T {}
| --------- ^^^^^ ^
| |
| unsatisfied trait bound introduced here
= note: 2 redundant requirements hidden
note: required for `()` to implement `Inductive`
--> $DIR/double-cycle-inductive-coinductive.rs:12:16
|
LL | impl<T: Trait> Inductive for T {}
| ----- ^^^^^^^^^ ^
| |
| unsatisfied trait bound introduced here
= note: 7 redundant requirements hidden
= note: required for `()` to implement `Trait`
note: required by a bound in `impls_trait`
--> $DIR/double-cycle-inductive-coinductive.rs:17:19
@ -26,19 +26,12 @@ note: required by a bound in `impls_trait`
LL | fn impls_trait<T: Trait>() {}
| ^^^^^ required by this bound in `impls_trait`
error[E0275]: overflow evaluating the requirement `(): TraitRev`
error[E0275]: overflow evaluating the requirement `(): CoinductiveRev`
--> $DIR/double-cycle-inductive-coinductive.rs:35:23
|
LL | impls_trait_rev::<()>();
| ^^
|
note: required for `()` to implement `CoinductiveRev`
--> $DIR/double-cycle-inductive-coinductive.rs:27:19
|
LL | impl<T: TraitRev> CoinductiveRev for T {}
| -------- ^^^^^^^^^^^^^^ ^
| |
| unsatisfied trait bound introduced here
note: required for `()` to implement `TraitRev`
--> $DIR/double-cycle-inductive-coinductive.rs:21:40
|
@ -46,7 +39,14 @@ LL | impl<T: CoinductiveRev + InductiveRev> TraitRev for T {}
| -------------- ^^^^^^^^ ^
| |
| unsatisfied trait bound introduced here
= note: 2 redundant requirements hidden
note: required for `()` to implement `CoinductiveRev`
--> $DIR/double-cycle-inductive-coinductive.rs:27:19
|
LL | impl<T: TraitRev> CoinductiveRev for T {}
| -------- ^^^^^^^^^^^^^^ ^
| |
| unsatisfied trait bound introduced here
= note: 7 redundant requirements hidden
= note: required for `()` to implement `TraitRev`
note: required by a bound in `impls_trait_rev`
--> $DIR/double-cycle-inductive-coinductive.rs:29:23

8
tests/ui/traits/next-solver/cycles/inductive-fixpoint-hang.stderr
View File

@ -1,10 +1,10 @@
error[E0275]: overflow evaluating the requirement `W<_>: Trait`
error[E0275]: overflow evaluating the requirement `W<W<_>>: Trait`
--> $DIR/inductive-fixpoint-hang.rs:31:19
|
LL | impls_trait::<W<_>>();
| ^^^^
|
note: required for `W<W<_>>` to implement `Trait`
note: required for `W<W<W<_>>>` to implement `Trait`
--> $DIR/inductive-fixpoint-hang.rs:22:17
|
LL | impl<T: ?Sized> Trait for W<W<T>>
@ -12,8 +12,8 @@ LL | impl<T: ?Sized> Trait for W<W<T>>
LL | where
LL | W<T>: Trait,
| ----- unsatisfied trait bound introduced here
= note: 3 redundant requirements hidden
= note: required for `W<W<W<W<W<_>>>>>` to implement `Trait`
= note: 8 redundant requirements hidden
= note: required for `W<W<W<W<W<W<W<W<W<W<W<_>>>>>>>>>>>` to implement `Trait`
note: required by a bound in `impls_trait`
--> $DIR/inductive-fixpoint-hang.rs:28:19
|

4
tests/ui/traits/next-solver/cycles/inductive-not-on-stack.rs
View File

@ -39,8 +39,8 @@ fn impls_ar<T: AR>() {}
fn main() {
impls_a::<()>();
//~^ ERROR overflow evaluating the requirement `(): A`
//~^ ERROR overflow evaluating the requirement `(): B`
impls_ar::<()>();
//~^ ERROR overflow evaluating the requirement `(): CR`
//~^ ERROR overflow evaluating the requirement `(): AR`
}

36
tests/ui/traits/next-solver/cycles/inductive-not-on-stack.stderr
View File

@ -1,16 +1,9 @@
error[E0275]: overflow evaluating the requirement `(): A`
error[E0275]: overflow evaluating the requirement `(): B`
--> $DIR/inductive-not-on-stack.rs:41:15
|
LL | impls_a::<()>();
| ^^
|
note: required for `()` to implement `B`
--> $DIR/inductive-not-on-stack.rs:22:12
|
LL | impl<T: A> B for T {}
| - ^ ^
| |
| unsatisfied trait bound introduced here
note: required for `()` to implement `A`
--> $DIR/inductive-not-on-stack.rs:21:16
|
@ -18,7 +11,14 @@ LL | impl<T: B + C> A for T {}
| - ^ ^
| |
| unsatisfied trait bound introduced here
= note: 2 redundant requirements hidden
note: required for `()` to implement `B`
--> $DIR/inductive-not-on-stack.rs:22:12
|
LL | impl<T: A> B for T {}
| - ^ ^
| |
| unsatisfied trait bound introduced here
= note: 7 redundant requirements hidden
= note: required for `()` to implement `A`
note: required by a bound in `impls_a`
--> $DIR/inductive-not-on-stack.rs:25:15
@ -26,19 +26,12 @@ note: required by a bound in `impls_a`
LL | fn impls_a<T: A>() {}
| ^ required by this bound in `impls_a`
error[E0275]: overflow evaluating the requirement `(): CR`
error[E0275]: overflow evaluating the requirement `(): AR`
--> $DIR/inductive-not-on-stack.rs:44:16
|
LL | impls_ar::<()>();
| ^^
|
note: required for `()` to implement `AR`
--> $DIR/inductive-not-on-stack.rs:34:18
|
LL | impl<T: CR + BR> AR for T {}
| -- ^^ ^
| |
| unsatisfied trait bound introduced here
note: required for `()` to implement `BR`
--> $DIR/inductive-not-on-stack.rs:35:13
|
@ -53,7 +46,14 @@ LL | impl<T: BR> CR for T {}
| -- ^^ ^
| |
| unsatisfied trait bound introduced here
= note: 1 redundant requirement hidden
note: required for `()` to implement `AR`
--> $DIR/inductive-not-on-stack.rs:34:18
|
LL | impl<T: CR + BR> AR for T {}
| -- ^^ ^
| |
| unsatisfied trait bound introduced here
= note: 6 redundant requirements hidden
= note: required for `()` to implement `AR`
note: required by a bound in `impls_ar`
--> $DIR/inductive-not-on-stack.rs:38:16

2
tests/ui/traits/next-solver/cycles/mixed-cycles-1.rs
View File

@ -35,5 +35,5 @@ fn impls_a<T: A>() {}
fn main() {
impls_a::<()>();
//~^ ERROR overflow evaluating the requirement `(): C`
//~^ ERROR overflow evaluating the requirement `(): CInd`
}

25
tests/ui/traits/next-solver/cycles/mixed-cycles-1.stderr
View File

@ -1,16 +1,9 @@
error[E0275]: overflow evaluating the requirement `(): C`
error[E0275]: overflow evaluating the requirement `(): CInd`
--> $DIR/mixed-cycles-1.rs:37:15
|
LL | impls_a::<()>();
| ^^
|
note: required for `()` to implement `CInd`
--> $DIR/mixed-cycles-1.rs:28:21
|
LL | impl<T: ?Sized + C> CInd for T {}
| - ^^^^ ^
| |
| unsatisfied trait bound introduced here
note: required for `()` to implement `B`
--> $DIR/mixed-cycles-1.rs:31:28
|
@ -18,6 +11,22 @@ LL | impl<T: ?Sized + CInd + C> B for T {}
| ---- ^ ^
| |
| unsatisfied trait bound introduced here
note: required for `()` to implement `C`
--> $DIR/mixed-cycles-1.rs:32:25
|
LL | impl<T: ?Sized + B + A> C for T {}
| - ^ ^
| |
| unsatisfied trait bound introduced here
note: required for `()` to implement `CInd`
--> $DIR/mixed-cycles-1.rs:28:21
|
LL | impl<T: ?Sized + C> CInd for T {}
| - ^^^^ ^
| |
| unsatisfied trait bound introduced here
= note: 4 redundant requirements hidden
= note: required for `()` to implement `B`
note: required for `()` to implement `BInd`
--> $DIR/mixed-cycles-1.rs:23:21
|

2
tests/ui/traits/next-solver/cycles/mixed-cycles-2.rs
View File

@ -28,5 +28,5 @@ fn impls_a<T: A>() {}
fn main() {
impls_a::<()>();
//~^ ERROR overflow evaluating the requirement `(): B`
//~^ ERROR overflow evaluating the requirement `(): BInd`
}

18
tests/ui/traits/next-solver/cycles/mixed-cycles-2.stderr
View File

@ -1,16 +1,9 @@
error[E0275]: overflow evaluating the requirement `(): B`
error[E0275]: overflow evaluating the requirement `(): BInd`
--> $DIR/mixed-cycles-2.rs:30:15
|
LL | impls_a::<()>();
| ^^
|
note: required for `()` to implement `BInd`
--> $DIR/mixed-cycles-2.rs:22:21
|
LL | impl<T: ?Sized + B> BInd for T {}
| - ^^^^ ^
| |
| unsatisfied trait bound introduced here
note: required for `()` to implement `B`
--> $DIR/mixed-cycles-2.rs:25:24
|
@ -18,7 +11,14 @@ LL | impl<T: ?Sized + BInd> B for T {}
| ---- ^ ^
| |
| unsatisfied trait bound introduced here
= note: 1 redundant requirement hidden
note: required for `()` to implement `BInd`
--> $DIR/mixed-cycles-2.rs:22:21
|
LL | impl<T: ?Sized + B> BInd for T {}
| - ^^^^ ^
| |
| unsatisfied trait bound introduced here
= note: 6 redundant requirements hidden
= note: required for `()` to implement `BInd`
note: required for `()` to implement `A`
--> $DIR/mixed-cycles-2.rs:24:28

4
tests/ui/traits/next-solver/overflow/global-cache.stderr
View File

@ -5,14 +5,14 @@ LL | impls_trait::<Four<Four<Four<Four<()>>>>>();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= help: consider increasing the recursion limit by adding a `#![recursion_limit = "18"]` attribute to your crate (`global_cache`)
note: required for `Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<()>>>>>>>>>>>>>` to implement `Trait`
note: required for `Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<()>>>>>>>>>>>` to implement `Trait`
--> $DIR/global-cache.rs:12:16
|
LL | impl<T: Trait> Trait for Inc<T> {}
| ----- ^^^^^ ^^^^^^
| |
| unsatisfied trait bound introduced here
= note: 3 redundant requirements hidden
= note: 5 redundant requirements hidden
= note: required for `Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<Inc<()>>>>>>>>>>>>>>>>` to implement `Trait`
note: required by a bound in `impls_trait`
--> $DIR/global-cache.rs:15:19