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Check that all hidden types are the same and then deduplicate them.

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This commit is contained in:
Oli Scherer 2022-04-06 15:02:37 +00:00
parent 201cf3dba3
commit 27dc503556
2 changed files with 111 additions and 63 deletions
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144
compiler/rustc_borrowck/src/region_infer/opaque_types.rs
View File

@ -55,75 +55,93 @@ impl<'tcx> RegionInferenceContext<'tcx> {
infcx: &InferCtxt<'_, 'tcx>,
opaque_ty_decls: VecMap<OpaqueTypeKey<'tcx>, (OpaqueHiddenType<'tcx>, OpaqueTyOrigin)>,
) -> VecMap<OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>> {
opaque_ty_decls
.into_iter()
.map(|(opaque_type_key, (concrete_type, origin))| {
let substs = opaque_type_key.substs;
debug!(?concrete_type, ?substs);
let mut result: VecMap<OpaqueTypeKey<'tcx>, OpaqueHiddenType<'tcx>> = VecMap::new();
for (opaque_type_key, (concrete_type, origin)) in opaque_ty_decls {
let substs = opaque_type_key.substs;
debug!(?concrete_type, ?substs);
let mut subst_regions = vec![self.universal_regions.fr_static];
let universal_substs = infcx.tcx.fold_regions(substs, &mut false, |region, _| {
if let ty::RePlaceholder(..) = region.kind() {
// Higher kinded regions don't need remapping, they don't refer to anything outside of this the substs.
return region;
let mut subst_regions = vec![self.universal_regions.fr_static];
let universal_substs = infcx.tcx.fold_regions(substs, &mut false, |region, _| {
if let ty::RePlaceholder(..) = region.kind() {
// Higher kinded regions don't need remapping, they don't refer to anything outside of this the substs.
return region;
}
let vid = self.to_region_vid(region);
trace!(?vid);
let scc = self.constraint_sccs.scc(vid);
trace!(?scc);
match self.scc_values.universal_regions_outlived_by(scc).find_map(|lb| {
self.eval_equal(vid, lb).then_some(self.definitions[lb].external_name?)
}) {
Some(region) => {
let vid = self.universal_regions.to_region_vid(region);
subst_regions.push(vid);
region
}
let vid = self.to_region_vid(region);
trace!(?vid);
let scc = self.constraint_sccs.scc(vid);
trace!(?scc);
match self.scc_values.universal_regions_outlived_by(scc).find_map(|lb| {
self.eval_equal(vid, lb).then_some(self.definitions[lb].external_name?)
}) {
Some(region) => {
let vid = self.universal_regions.to_region_vid(region);
subst_regions.push(vid);
region
}
None => {
subst_regions.push(vid);
infcx.tcx.sess.delay_span_bug(
concrete_type.span,
"opaque type with non-universal region substs",
);
infcx.tcx.lifetimes.re_static
}
None => {
subst_regions.push(vid);
infcx.tcx.sess.delay_span_bug(
concrete_type.span,
"opaque type with non-universal region substs",
);
infcx.tcx.lifetimes.re_static
}
}
});
subst_regions.sort();
subst_regions.dedup();
let universal_concrete_type =
infcx.tcx.fold_regions(concrete_type, &mut false, |region, _| match *region {
ty::ReVar(vid) => subst_regions
.iter()
.find(|ur_vid| self.eval_equal(vid, **ur_vid))
.and_then(|ur_vid| self.definitions[*ur_vid].external_name)
.unwrap_or(infcx.tcx.lifetimes.re_root_empty),
_ => region,
});
subst_regions.sort();
subst_regions.dedup();
debug!(?universal_concrete_type, ?universal_substs);
let universal_concrete_type =
infcx.tcx.fold_regions(concrete_type, &mut false, |region, _| match *region {
ty::ReVar(vid) => subst_regions
.iter()
.find(|ur_vid| self.eval_equal(vid, **ur_vid))
.and_then(|ur_vid| self.definitions[*ur_vid].external_name)
.unwrap_or(infcx.tcx.lifetimes.re_root_empty),
_ => region,
});
debug!(?universal_concrete_type, ?universal_substs);
let opaque_type_key =
OpaqueTypeKey { def_id: opaque_type_key.def_id, substs: universal_substs };
let remapped_type = infcx.infer_opaque_definition_from_instantiation(
opaque_type_key,
universal_concrete_type,
);
let ty = if check_opaque_type_parameter_valid(
infcx.tcx,
opaque_type_key,
origin,
concrete_type.span,
) {
remapped_type
} else {
infcx.tcx.ty_error()
};
(opaque_type_key, OpaqueHiddenType { ty, span: concrete_type.span })
})
.collect()
let opaque_type_key =
OpaqueTypeKey { def_id: opaque_type_key.def_id, substs: universal_substs };
let remapped_type = infcx.infer_opaque_definition_from_instantiation(
opaque_type_key,
universal_concrete_type,
);
let ty = if check_opaque_type_parameter_valid(
infcx.tcx,
opaque_type_key,
origin,
concrete_type.span,
) {
remapped_type
} else {
infcx.tcx.ty_error()
};
// Sometimes two opaque types are the same only after we remap the generic parameters
// back to the opaque type definition. E.g. we may have `OpaqueType<X, Y>` mapped to `(X, Y)`
// and `OpaqueType<Y, X>` mapped to `(Y, X)`, and those are the same, but we only know that
// once we convert the generic parameters to those of the opaque type.
if let Some(prev) = result.get_mut(&opaque_type_key) {
if prev.ty != ty {
let mut err = infcx.tcx.sess.struct_span_err(
concrete_type.span,
&format!("hidden type `{}` differed from previous `{}`", ty, prev.ty),
);
err.span_note(prev.span, "previous hidden type bound here");
err.emit();
prev.ty = infcx.tcx.ty_error();
}
// Pick a better span if there is one.
// FIXME(oli-obk): collect multiple spans for better diagnostics down the road.
prev.span = prev.span.substitute_dummy(concrete_type.span);
} else {
result.insert(opaque_type_key, OpaqueHiddenType { ty, span: concrete_type.span });
}
}
result
}
/// Map the regions in the type to named regions. This is similar to what

30
src/test/ui/type-alias-impl-trait/multiple_definitions.rs Normal file
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@ -0,0 +1,30 @@
// check-pass
use std::marker::PhantomData;
pub struct ConcreteError {}
pub trait IoBase {}
struct X {}
impl IoBase for X {}
pub struct ClusterIterator<B, E, S = B> {
pub fat: B,
phantom_s: PhantomData<S>,
phantom_e: PhantomData<E>,
}
pub struct FileSystem<IO: IoBase> {
pub disk: IO,
}
impl<IO: IoBase> FileSystem<IO> {
pub fn cluster_iter(&self) -> ClusterIterator<impl IoBase + '_, ConcreteError> {
ClusterIterator {
fat: X {},
phantom_s: PhantomData::default(),
phantom_e: PhantomData::default(),
}
}
}
fn main() {}