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merged 2 commits into from
Jul 18, 2022
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Don't pass InferCtxt to WfPredicates #99137

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2d15f1c
Don't try to resolve inference variables in WF computation, just regi…
jackh726 Jul 10, 2022
a479f23
Don't pass InferCtxt to WfPredicates
jackh726 Jul 10, 2022
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104 changes: 46 additions & 58 deletions compiler/rustc_trait_selection/src/traits/wf.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -60,12 +60,19 @@ pub fn obligations<'a, 'tcx>(
GenericArgKind::Lifetime(..) => return Some(Vec::new()),
};

let mut wf =
WfPredicates { infcx, param_env, body_id, span, out: vec![], recursion_depth, item: None };
let mut wf = WfPredicates {
tcx: infcx.tcx,
param_env,
body_id,
span,
out: vec![],
recursion_depth,
item: None,
};
wf.compute(arg);
debug!("wf::obligations({:?}, body_id={:?}) = {:?}", arg, body_id, wf.out);

let result = wf.normalize();
let result = wf.normalize(infcx);
debug!("wf::obligations({:?}, body_id={:?}) ~~> {:?}", arg, body_id, result);
Some(result)
}
Expand All @@ -83,7 +90,7 @@ pub fn trait_obligations<'a, 'tcx>(
item: &'tcx hir::Item<'tcx>,
) -> Vec<traits::PredicateObligation<'tcx>> {
let mut wf = WfPredicates {
infcx,
tcx: infcx.tcx,
param_env,
body_id,
span,
Expand All @@ -93,7 +100,7 @@ pub fn trait_obligations<'a, 'tcx>(
};
wf.compute_trait_ref(trait_ref, Elaborate::All);
debug!(obligations = ?wf.out);
wf.normalize()
wf.normalize(infcx)
}

pub fn predicate_obligations<'a, 'tcx>(
Expand All @@ -104,7 +111,7 @@ pub fn predicate_obligations<'a, 'tcx>(
span: Span,
) -> Vec<traits::PredicateObligation<'tcx>> {
let mut wf = WfPredicates {
infcx,
tcx: infcx.tcx,
param_env,
body_id,
span,
Expand Down Expand Up @@ -159,11 +166,11 @@ pub fn predicate_obligations<'a, 'tcx>(
}
}

wf.normalize()
wf.normalize(infcx)
}

struct WfPredicates<'a, 'tcx> {
infcx: &'a InferCtxt<'a, 'tcx>,
struct WfPredicates<'tcx> {
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
body_id: hir::HirId,
span: Span,
Expand Down Expand Up @@ -260,18 +267,17 @@ fn extend_cause_with_original_assoc_item_obligation<'tcx>(
}
}

impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
impl<'tcx> WfPredicates<'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.infcx.tcx
self.tcx
}

fn cause(&self, code: traits::ObligationCauseCode<'tcx>) -> traits::ObligationCause<'tcx> {
traits::ObligationCause::new(self.span, self.body_id, code)
}

fn normalize(mut self) -> Vec<traits::PredicateObligation<'tcx>> {
fn normalize(self, infcx: &InferCtxt<'_, 'tcx>) -> Vec<traits::PredicateObligation<'tcx>> {
let cause = self.cause(traits::WellFormed(None));
let infcx = &mut self.infcx;
let param_env = self.param_env;
let mut obligations = Vec::with_capacity(self.out.len());
for mut obligation in self.out {
Expand All @@ -296,7 +302,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {

/// Pushes the obligations required for `trait_ref` to be WF into `self.out`.
fn compute_trait_ref(&mut self, trait_ref: &ty::TraitRef<'tcx>, elaborate: Elaborate) {
let tcx = self.infcx.tcx;
let tcx = self.tcx;
let obligations = self.nominal_obligations(trait_ref.def_id, trait_ref.substs);

debug!("compute_trait_ref obligations {:?}", obligations);
Expand Down Expand Up @@ -410,14 +416,14 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
if !subty.has_escaping_bound_vars() {
let cause = self.cause(cause);
let trait_ref = ty::TraitRef {
def_id: self.infcx.tcx.require_lang_item(LangItem::Sized, None),
substs: self.infcx.tcx.mk_substs_trait(subty, &[]),
def_id: self.tcx.require_lang_item(LangItem::Sized, None),
substs: self.tcx.mk_substs_trait(subty, &[]),
};
self.out.push(traits::Obligation::with_depth(
cause,
self.recursion_depth,
self.param_env,
ty::Binder::dummy(trait_ref).without_const().to_predicate(self.infcx.tcx),
ty::Binder::dummy(trait_ref).without_const().to_predicate(self.tcx),
));
}
}
Expand Down Expand Up @@ -452,26 +458,16 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
predicate,
));
}
ty::ConstKind::Infer(infer) => {
let resolved = self.infcx.shallow_resolve(infer);
// the `InferConst` changed, meaning that we made progress.
if resolved != infer {
let cause = self.cause(traits::WellFormed(None));

let resolved_constant = self.infcx.tcx.mk_const(ty::ConstS {
kind: ty::ConstKind::Infer(resolved),
ty: constant.ty(),
});
self.out.push(traits::Obligation::with_depth(
cause,
self.recursion_depth,
self.param_env,
ty::Binder::dummy(ty::PredicateKind::WellFormed(
resolved_constant.into(),
))
ty::ConstKind::Infer(_) => {
let cause = self.cause(traits::WellFormed(None));

self.out.push(traits::Obligation::with_depth(
cause,
self.recursion_depth,
self.param_env,
ty::Binder::dummy(ty::PredicateKind::WellFormed(constant.into()))
.to_predicate(self.tcx()),
));
}
));
}
ty::ConstKind::Error(_)
| ty::ConstKind::Param(_)
Expand Down Expand Up @@ -627,7 +623,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
// of whatever returned this exact `impl Trait`.

// for named opaque `impl Trait` types we still need to check them
if ty::is_impl_trait_defn(self.infcx.tcx, did).is_none() {
if ty::is_impl_trait_defn(self.tcx, did).is_none() {
let obligations = self.nominal_obligations(did, substs);
self.out.extend(obligations);
}
Expand Down Expand Up @@ -675,22 +671,14 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
// See also the comment on `fn obligations`, describing "livelock"
// prevention, which happens before this can be reached.
ty::Infer(_) => {
let ty = self.infcx.shallow_resolve(ty);
if let ty::Infer(ty::TyVar(_)) = ty.kind() {
// Not yet resolved, but we've made progress.
let cause = self.cause(traits::WellFormed(None));
self.out.push(traits::Obligation::with_depth(
cause,
self.recursion_depth,
param_env,
ty::Binder::dummy(ty::PredicateKind::WellFormed(ty.into()))
.to_predicate(self.tcx()),
));
} else {
// Yes, resolved, proceed with the result.
// FIXME(eddyb) add the type to `walker` instead of recursing.
self.compute(ty.into());
}
let cause = self.cause(traits::WellFormed(None));
self.out.push(traits::Obligation::with_depth(
cause,
self.recursion_depth,
param_env,
ty::Binder::dummy(ty::PredicateKind::WellFormed(ty.into()))
.to_predicate(self.tcx()),
));
}
}
}
Expand All @@ -701,15 +689,15 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
def_id: DefId,
substs: SubstsRef<'tcx>,
) -> Vec<traits::PredicateObligation<'tcx>> {
let predicates = self.infcx.tcx.predicates_of(def_id);
let predicates = self.tcx.predicates_of(def_id);
let mut origins = vec![def_id; predicates.predicates.len()];
let mut head = predicates;
while let Some(parent) = head.parent {
head = self.infcx.tcx.predicates_of(parent);
head = self.tcx.predicates_of(parent);
origins.extend(iter::repeat(parent).take(head.predicates.len()));
}

let predicates = predicates.instantiate(self.infcx.tcx, substs);
let predicates = predicates.instantiate(self.tcx, substs);
debug_assert_eq!(predicates.predicates.len(), origins.len());

iter::zip(iter::zip(predicates.predicates, predicates.spans), origins.into_iter().rev())
Expand Down Expand Up @@ -764,7 +752,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
// Note: in fact we only permit builtin traits, not `Bar<'d>`, I
// am looking forward to the future here.
if !data.has_escaping_bound_vars() && !region.has_escaping_bound_vars() {
let implicit_bounds = object_region_bounds(self.infcx.tcx, data);
let implicit_bounds = object_region_bounds(self.tcx, data);

let explicit_bound = region;

Expand All @@ -777,7 +765,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
cause,
self.recursion_depth,
self.param_env,
outlives.to_predicate(self.infcx.tcx),
outlives.to_predicate(self.tcx),
));
}
}
Expand Down
11 changes: 8 additions & 3 deletions src/test/ui/issues/issue-98299.stderr
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Original file line number Diff line number Diff line change
@@ -1,8 +1,13 @@
error[E0282]: type annotations needed
--> $DIR/issue-98299.rs:4:5
error[E0282]: type annotations needed for `SmallCString<N>`
--> $DIR/issue-98299.rs:4:36
|
LL | SmallCString::try_from(p).map(|cstr| cstr);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot infer type for enum `Result<SmallCString<{_: usize}>, ()>`
| ^^^^
|
help: consider giving this closure parameter an explicit type, where the the value of const parameter `N` is specified
|
LL | SmallCString::try_from(p).map(|cstr: SmallCString<N>| cstr);
| +++++++++++++++++

error: aborting due to previous error

Expand Down