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Split relate_substs into two functions

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One for the case with variances, and one without.
All callers use an explicit Option for the variable anyway.
This commit is contained in:
Martin Gammelsæter 2022-04-17 11:04:58 +02:00
parent 041121a184
commit 19dedf3a4b
3 changed files with 42 additions and 31 deletions
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10
compiler/rustc_infer/src/infer/combine.rs
View File

@ -567,11 +567,17 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
// Avoid fetching the variance if we are in an invariant
// context; no need, and it can induce dependency cycles
// (e.g., #41849).
relate::relate_substs(self, None, a_subst, b_subst)
relate::relate_substs(self, a_subst, b_subst)
} else {
let tcx = self.tcx();
let opt_variances = tcx.variances_of(item_def_id);
relate::relate_substs(self, Some((item_def_id, &opt_variances)), a_subst, b_subst)
relate::relate_substs_with_variances(
self,
item_def_id,
&opt_variances,
a_subst,
b_subst,
)
}
}

2
compiler/rustc_infer/src/infer/equate.rs
View File

@ -53,7 +53,7 @@ impl<'tcx> TypeRelation<'tcx> for Equate<'_, '_, 'tcx> {
// performing trait matching (which then performs equality
// unification).
relate::relate_substs(self, None, a_subst, b_subst)
relate::relate_substs(self, a_subst, b_subst)
}
fn relate_with_variance<T: Relate<'tcx>>(

61
compiler/rustc_middle/src/ty/relate.rs
View File

@ -61,7 +61,7 @@ pub trait TypeRelation<'tcx>: Sized {
let tcx = self.tcx();
let opt_variances = tcx.variances_of(item_def_id);
relate_substs(self, Some((item_def_id, opt_variances)), a_subst, b_subst)
relate_substs_with_variances(self, item_def_id, opt_variances, a_subst, b_subst)
}
/// Switch variance for the purpose of relating `a` and `b`.
@ -135,34 +135,39 @@ pub fn relate_type_and_mut<'tcx, R: TypeRelation<'tcx>>(
}
}
#[inline]
pub fn relate_substs<'tcx, R: TypeRelation<'tcx>>(
relation: &mut R,
variances: Option<(DefId, &[ty::Variance])>,
a_subst: SubstsRef<'tcx>,
b_subst: SubstsRef<'tcx>,
) -> RelateResult<'tcx, SubstsRef<'tcx>> {
relation.tcx().mk_substs(iter::zip(a_subst, b_subst).map(|(a, b)| {
relation.relate_with_variance(ty::Invariant, ty::VarianceDiagInfo::default(), a, b)
}))
}
pub fn relate_substs_with_variances<'tcx, R: TypeRelation<'tcx>>(
relation: &mut R,
ty_def_id: DefId,
variances: &[ty::Variance],
a_subst: SubstsRef<'tcx>,
b_subst: SubstsRef<'tcx>,
) -> RelateResult<'tcx, SubstsRef<'tcx>> {
let tcx = relation.tcx();
let zipped = iter::zip(a_subst, b_subst);
match variances {
Some((ty_def_id, variances)) => {
let mut cached_ty = None;
tcx.mk_substs(zipped.enumerate().map(|(i, (a, b))| {
let variance = variances[i];
let variance_info = if variance == ty::Invariant {
let ty = *cached_ty
.get_or_insert_with(|| tcx.type_of(ty_def_id).subst(tcx, a_subst));
ty::VarianceDiagInfo::Invariant { ty, param_index: i.try_into().unwrap() }
} else {
ty::VarianceDiagInfo::default()
};
relation.relate_with_variance(variance, variance_info, a, b)
}))
}
None => tcx.mk_substs(zipped.map(|(a, b)| {
relation.relate_with_variance(ty::Invariant, ty::VarianceDiagInfo::default(), a, b)
})),
}
let mut cached_ty = None;
let params = iter::zip(a_subst, b_subst).enumerate().map(|(i, (a, b))| {
let variance = variances[i];
let variance_info = if variance == ty::Invariant {
let ty = *cached_ty.get_or_insert_with(|| tcx.type_of(ty_def_id).subst(tcx, a_subst));
ty::VarianceDiagInfo::Invariant { ty, param_index: i.try_into().unwrap() }
} else {
ty::VarianceDiagInfo::default()
};
relation.relate_with_variance(variance, variance_info, a, b)
});
tcx.mk_substs(params)
}
impl<'tcx> Relate<'tcx> for ty::FnSig<'tcx> {
@ -318,7 +323,7 @@ impl<'tcx> Relate<'tcx> for ty::TraitRef<'tcx> {
if a.def_id != b.def_id {
Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id)))
} else {
let substs = relate_substs(relation, None, a.substs, b.substs)?;
let substs = relate_substs(relation, a.substs, b.substs)?;
Ok(ty::TraitRef { def_id: a.def_id, substs })
}
}
@ -334,7 +339,7 @@ impl<'tcx> Relate<'tcx> for ty::ExistentialTraitRef<'tcx> {
if a.def_id != b.def_id {
Err(TypeError::Traits(expected_found(relation, a.def_id, b.def_id)))
} else {
let substs = relate_substs(relation, None, a.substs, b.substs)?;
let substs = relate_substs(relation, a.substs, b.substs)?;
Ok(ty::ExistentialTraitRef { def_id: a.def_id, substs })
}
}
@ -554,7 +559,7 @@ pub fn super_relate_tys<'tcx, R: TypeRelation<'tcx>>(
(&ty::Opaque(a_def_id, a_substs), &ty::Opaque(b_def_id, b_substs))
if a_def_id == b_def_id =>
{
let substs = relate_substs(relation, None, a_substs, b_substs)?;
let substs = relate_substs(relation, a_substs, b_substs)?;
Ok(tcx.mk_opaque(a_def_id, substs))
}
@ -742,7 +747,7 @@ impl<'tcx> Relate<'tcx> for ty::ClosureSubsts<'tcx> {
a: ty::ClosureSubsts<'tcx>,
b: ty::ClosureSubsts<'tcx>,
) -> RelateResult<'tcx, ty::ClosureSubsts<'tcx>> {
let substs = relate_substs(relation, None, a.substs, b.substs)?;
let substs = relate_substs(relation, a.substs, b.substs)?;
Ok(ty::ClosureSubsts { substs })
}
}
@ -753,7 +758,7 @@ impl<'tcx> Relate<'tcx> for ty::GeneratorSubsts<'tcx> {
a: ty::GeneratorSubsts<'tcx>,
b: ty::GeneratorSubsts<'tcx>,
) -> RelateResult<'tcx, ty::GeneratorSubsts<'tcx>> {
let substs = relate_substs(relation, None, a.substs, b.substs)?;
let substs = relate_substs(relation, a.substs, b.substs)?;
Ok(ty::GeneratorSubsts { substs })
}
}
@ -764,7 +769,7 @@ impl<'tcx> Relate<'tcx> for SubstsRef<'tcx> {
a: SubstsRef<'tcx>,
b: SubstsRef<'tcx>,
) -> RelateResult<'tcx, SubstsRef<'tcx>> {
relate_substs(relation, None, a, b)
relate_substs(relation, a, b)
}
}