Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Add variance-related information to lifetime error messages #85343

Merged
merged 1 commit into from
Jun 6, 2021
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 6 additions & 1 deletion compiler/rustc_infer/src/infer/canonical/query_response.rs
Original file line number Diff line number Diff line change
Expand Up @@ -660,7 +660,12 @@ impl<'tcx> TypeRelatingDelegate<'tcx> for QueryTypeRelatingDelegate<'_, 'tcx> {
)
}

fn push_outlives(&mut self, sup: ty::Region<'tcx>, sub: ty::Region<'tcx>) {
fn push_outlives(
&mut self,
sup: ty::Region<'tcx>,
sub: ty::Region<'tcx>,
_info: ty::VarianceDiagInfo<'tcx>,
) {
self.obligations.push(Obligation {
cause: self.cause.clone(),
param_env: self.param_env,
Expand Down
25 changes: 20 additions & 5 deletions compiler/rustc_infer/src/infer/combine.rs
Original file line number Diff line number Diff line change
Expand Up @@ -371,9 +371,12 @@ impl<'infcx, 'tcx> CombineFields<'infcx, 'tcx> {
match dir {
EqTo => self.equate(a_is_expected).relate(a_ty, b_ty),
SubtypeOf => self.sub(a_is_expected).relate(a_ty, b_ty),
SupertypeOf => {
self.sub(a_is_expected).relate_with_variance(ty::Contravariant, a_ty, b_ty)
}
SupertypeOf => self.sub(a_is_expected).relate_with_variance(
ty::Contravariant,
ty::VarianceDiagInfo::default(),
a_ty,
b_ty,
),
}?;

Ok(())
Expand Down Expand Up @@ -574,6 +577,7 @@ impl TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
_info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
Expand Down Expand Up @@ -737,7 +741,12 @@ impl TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
if self.tcx().lazy_normalization() =>
{
assert_eq!(promoted, None);
let substs = self.relate_with_variance(ty::Variance::Invariant, substs, substs)?;
let substs = self.relate_with_variance(
ty::Variance::Invariant,
ty::VarianceDiagInfo::default(),
substs,
substs,
)?;
Ok(self.tcx().mk_const(ty::Const {
ty: c.ty,
val: ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted }),
Expand Down Expand Up @@ -831,6 +840,7 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
_variance: ty::Variance,
_info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
Expand Down Expand Up @@ -965,7 +975,12 @@ impl TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
if self.tcx().lazy_normalization() =>
{
assert_eq!(promoted, None);
let substs = self.relate_with_variance(ty::Variance::Invariant, substs, substs)?;
let substs = self.relate_with_variance(
ty::Variance::Invariant,
ty::VarianceDiagInfo::default(),
substs,
substs,
)?;
Ok(self.tcx().mk_const(ty::Const {
ty: c.ty,
val: ty::ConstKind::Unevaluated(ty::Unevaluated { def, substs, promoted }),
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_infer/src/infer/equate.rs
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@ impl TypeRelation<'tcx> for Equate<'combine, 'infcx, 'tcx> {
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
_: ty::Variance,
_info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
Expand Down
3 changes: 2 additions & 1 deletion compiler/rustc_infer/src/infer/glb.rs
Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ impl TypeRelation<'tcx> for Glb<'combine, 'infcx, 'tcx> {
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
_info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
Expand Down Expand Up @@ -96,7 +97,7 @@ impl TypeRelation<'tcx> for Glb<'combine, 'infcx, 'tcx> {
// When higher-ranked types are involved, computing the LUB is
// very challenging, switch to invariance. This is obviously
// overly conservative but works ok in practice.
self.relate_with_variance(ty::Variance::Invariant, a, b)?;
self.relate_with_variance(ty::Variance::Invariant, ty::VarianceDiagInfo::default(), a, b)?;
Ok(a)
}
}
Expand Down
3 changes: 2 additions & 1 deletion compiler/rustc_infer/src/infer/lub.rs
Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ impl TypeRelation<'tcx> for Lub<'combine, 'infcx, 'tcx> {
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
_info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
Expand Down Expand Up @@ -96,7 +97,7 @@ impl TypeRelation<'tcx> for Lub<'combine, 'infcx, 'tcx> {
// When higher-ranked types are involved, computing the LUB is
// very challenging, switch to invariance. This is obviously
// overly conservative but works ok in practice.
self.relate_with_variance(ty::Variance::Invariant, a, b)?;
self.relate_with_variance(ty::Variance::Invariant, ty::VarianceDiagInfo::default(), a, b)?;
Ok(a)
}
}
Expand Down
34 changes: 28 additions & 6 deletions compiler/rustc_infer/src/infer/nll_relate/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,8 @@ where
/// - Bivariant means that it doesn't matter.
ambient_variance: ty::Variance,

ambient_variance_info: ty::VarianceDiagInfo<'tcx>,

/// When we pass through a set of binders (e.g., when looking into
/// a `fn` type), we push a new bound region scope onto here. This
/// will contain the instantiated region for each region in those
Expand All @@ -78,7 +80,12 @@ pub trait TypeRelatingDelegate<'tcx> {
/// satisfied for the two types to be related. `sub` and `sup` may
/// be regions from the type or new variables created through the
/// delegate.
fn push_outlives(&mut self, sup: ty::Region<'tcx>, sub: ty::Region<'tcx>);
fn push_outlives(
&mut self,
sup: ty::Region<'tcx>,
sub: ty::Region<'tcx>,
info: ty::VarianceDiagInfo<'tcx>,
);

fn const_equate(&mut self, a: &'tcx ty::Const<'tcx>, b: &'tcx ty::Const<'tcx>);

Expand Down Expand Up @@ -138,7 +145,14 @@ where
delegate: D,
ambient_variance: ty::Variance,
) -> Self {
Self { infcx, delegate, ambient_variance, a_scopes: vec![], b_scopes: vec![] }
Self {
infcx,
delegate,
ambient_variance,
ambient_variance_info: ty::VarianceDiagInfo::default(),
a_scopes: vec![],
b_scopes: vec![],
}
}

fn ambient_covariance(&self) -> bool {
Expand Down Expand Up @@ -239,10 +253,15 @@ where

/// Push a new outlives requirement into our output set of
/// constraints.
fn push_outlives(&mut self, sup: ty::Region<'tcx>, sub: ty::Region<'tcx>) {
fn push_outlives(
&mut self,
sup: ty::Region<'tcx>,
sub: ty::Region<'tcx>,
info: ty::VarianceDiagInfo<'tcx>,
) {
debug!("push_outlives({:?}: {:?})", sup, sub);

self.delegate.push_outlives(sup, sub);
self.delegate.push_outlives(sup, sub, info);
}

/// Relate a projection type and some value type lazily. This will always
Expand Down Expand Up @@ -490,13 +509,15 @@ where
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
debug!("relate_with_variance(variance={:?}, a={:?}, b={:?})", variance, a, b);

let old_ambient_variance = self.ambient_variance;
self.ambient_variance = self.ambient_variance.xform(variance);
self.ambient_variance_info = self.ambient_variance_info.clone().xform(info);

debug!("relate_with_variance: ambient_variance = {:?}", self.ambient_variance);

Expand Down Expand Up @@ -574,12 +595,12 @@ where

if self.ambient_covariance() {
// Covariance: a <= b. Hence, `b: a`.
self.push_outlives(v_b, v_a);
self.push_outlives(v_b, v_a, self.ambient_variance_info.clone());
}

if self.ambient_contravariance() {
// Contravariant: b <= a. Hence, `a: b`.
self.push_outlives(v_a, v_b);
self.push_outlives(v_a, v_b, self.ambient_variance_info.clone());
}

Ok(a)
Expand Down Expand Up @@ -835,6 +856,7 @@ where
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
_info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_infer/src/infer/sub.rs
Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,7 @@ impl TypeRelation<'tcx> for Sub<'combine, 'infcx, 'tcx> {
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
_info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_middle/src/ty/_match.rs
Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ impl TypeRelation<'tcx> for Match<'tcx> {
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
_: ty::Variance,
_: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T> {
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_middle/src/ty/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -71,7 +71,7 @@ pub use self::sty::{
ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
GeneratorSubsts, GeneratorSubstsParts, ParamConst, ParamTy, PolyExistentialProjection,
PolyExistentialTraitRef, PolyFnSig, PolyGenSig, PolyTraitRef, ProjectionTy, Region, RegionKind,
RegionVid, TraitRef, TyKind, TypeAndMut, UpvarSubsts,
RegionVid, TraitRef, TyKind, TypeAndMut, UpvarSubsts, VarianceDiagInfo, VarianceDiagMutKind,
};
pub use self::trait_def::TraitDef;

Expand Down
85 changes: 57 additions & 28 deletions compiler/rustc_middle/src/ty/relate.rs
Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,7 @@ pub trait TypeRelation<'tcx>: Sized {
fn relate_with_variance<T: Relate<'tcx>>(
&mut self,
variance: ty::Variance,
info: ty::VarianceDiagInfo<'tcx>,
a: T,
b: T,
) -> RelateResult<'tcx, T>;
Expand Down Expand Up @@ -111,24 +112,23 @@ pub trait Relate<'tcx>: TypeFoldable<'tcx> + Copy {
///////////////////////////////////////////////////////////////////////////
// Relate impls

impl<'tcx> Relate<'tcx> for ty::TypeAndMut<'tcx> {
fn relate<R: TypeRelation<'tcx>>(
relation: &mut R,
a: ty::TypeAndMut<'tcx>,
b: ty::TypeAndMut<'tcx>,
) -> RelateResult<'tcx, ty::TypeAndMut<'tcx>> {
debug!("{}.mts({:?}, {:?})", relation.tag(), a, b);
if a.mutbl != b.mutbl {
Err(TypeError::Mutability)
} else {
let mutbl = a.mutbl;
let variance = match mutbl {
ast::Mutability::Not => ty::Covariant,
ast::Mutability::Mut => ty::Invariant,
};
let ty = relation.relate_with_variance(variance, a.ty, b.ty)?;
Ok(ty::TypeAndMut { ty, mutbl })
}
fn relate_type_and_mut<'tcx, R: TypeRelation<'tcx>>(
relation: &mut R,
a: ty::TypeAndMut<'tcx>,
b: ty::TypeAndMut<'tcx>,
kind: ty::VarianceDiagMutKind,
) -> RelateResult<'tcx, ty::TypeAndMut<'tcx>> {
debug!("{}.mts({:?}, {:?})", relation.tag(), a, b);
if a.mutbl != b.mutbl {
Err(TypeError::Mutability)
} else {
let mutbl = a.mutbl;
let (variance, info) = match mutbl {
ast::Mutability::Not => (ty::Covariant, ty::VarianceDiagInfo::None),
ast::Mutability::Mut => (ty::Invariant, ty::VarianceDiagInfo::Mut { kind, ty: a.ty }),
};
let ty = relation.relate_with_variance(variance, info, a.ty, b.ty)?;
Ok(ty::TypeAndMut { ty, mutbl })
}
}

Expand All @@ -142,7 +142,7 @@ pub fn relate_substs<R: TypeRelation<'tcx>>(

let params = iter::zip(a_subst, b_subst).enumerate().map(|(i, (a, b))| {
let variance = variances.map_or(ty::Invariant, |v| v[i]);
relation.relate_with_variance(variance, a, b)
relation.relate_with_variance(variance, ty::VarianceDiagInfo::default(), a, b)
});

tcx.mk_substs(params)
Expand Down Expand Up @@ -177,7 +177,12 @@ impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
if is_output {
relation.relate(a, b)
} else {
relation.relate_with_variance(ty::Contravariant, a, b)
relation.relate_with_variance(
ty::Contravariant,
ty::VarianceDiagInfo::default(),
a,
b,
)
}
})
.enumerate()
Expand Down Expand Up @@ -251,8 +256,18 @@ impl<'tcx> Relate<'tcx> for ty::ExistentialProjection<'tcx> {
b.item_def_id,
)))
} else {
let ty = relation.relate_with_variance(ty::Invariant, a.ty, b.ty)?;
let substs = relation.relate_with_variance(ty::Invariant, a.substs, b.substs)?;
let ty = relation.relate_with_variance(
ty::Invariant,
ty::VarianceDiagInfo::default(),
a.ty,
b.ty,
)?;
let substs = relation.relate_with_variance(
ty::Invariant,
ty::VarianceDiagInfo::default(),
a.substs,
b.substs,
)?;
Ok(ty::ExistentialProjection { item_def_id: a.item_def_id, substs, ty })
}
}
Expand Down Expand Up @@ -364,7 +379,12 @@ pub fn super_relate_tys<R: TypeRelation<'tcx>>(

(&ty::Dynamic(a_obj, a_region), &ty::Dynamic(b_obj, b_region)) => {
let region_bound = relation.with_cause(Cause::ExistentialRegionBound, |relation| {
relation.relate_with_variance(ty::Contravariant, a_region, b_region)
relation.relate_with_variance(
ty::Contravariant,
ty::VarianceDiagInfo::default(),
a_region,
b_region,
)
})?;
Ok(tcx.mk_dynamic(relation.relate(a_obj, b_obj)?, region_bound))
}
Expand Down Expand Up @@ -398,15 +418,20 @@ pub fn super_relate_tys<R: TypeRelation<'tcx>>(
}

(&ty::RawPtr(a_mt), &ty::RawPtr(b_mt)) => {
let mt = relation.relate(a_mt, b_mt)?;
let mt = relate_type_and_mut(relation, a_mt, b_mt, ty::VarianceDiagMutKind::RawPtr)?;
Ok(tcx.mk_ptr(mt))
}

(&ty::Ref(a_r, a_ty, a_mutbl), &ty::Ref(b_r, b_ty, b_mutbl)) => {
let r = relation.relate_with_variance(ty::Contravariant, a_r, b_r)?;
let r = relation.relate_with_variance(
ty::Contravariant,
ty::VarianceDiagInfo::default(),
a_r,
b_r,
)?;
let a_mt = ty::TypeAndMut { ty: a_ty, mutbl: a_mutbl };
let b_mt = ty::TypeAndMut { ty: b_ty, mutbl: b_mutbl };
let mt = relation.relate(a_mt, b_mt)?;
let mt = relate_type_and_mut(relation, a_mt, b_mt, ty::VarianceDiagMutKind::Ref)?;
Ok(tcx.mk_ref(r, mt))
}

Expand Down Expand Up @@ -536,8 +561,12 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
(ty::ConstKind::Unevaluated(au), ty::ConstKind::Unevaluated(bu))
if au.def == bu.def && au.promoted == bu.promoted =>
{
let substs =
relation.relate_with_variance(ty::Variance::Invariant, au.substs, bu.substs)?;
let substs = relation.relate_with_variance(
ty::Variance::Invariant,
ty::VarianceDiagInfo::default(),
au.substs,
bu.substs,
)?;
return Ok(tcx.mk_const(ty::Const {
val: ty::ConstKind::Unevaluated(ty::Unevaluated {
def: au.def,
Expand Down
Loading