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Adapt TypeFolder implementors to return a Result

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Co-authored-by: Alan Egerton <eggyal@gmail.com>
This commit is contained in:
LeSeulArtichaut 2021-05-19 15:01:30 +02:00 • committed by Alan Egerton
parent 6e3fa20b00
commit 6dc3dae46f
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GPG key ID: 07CAC3CCA7E0643F
24 changed files with 387 additions and 305 deletions
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34
compiler/rustc_traits/src/chalk/lowering.rs
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@ -943,20 +943,23 @@ impl<'a, 'tcx> TypeFolder<'tcx> for NamedBoundVarSubstitutor<'a, 'tcx> {
self.tcx
}
fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: Binder<'tcx, T>) -> Binder<'tcx, T> {
fn fold_binder<T: TypeFoldable<'tcx>>(
&mut self,
t: Binder<'tcx, T>,
) -> Result<Binder<'tcx, T>, Self::Error> {
self.binder_index.shift_in(1);
let result = t.super_fold_with(self);
self.binder_index.shift_out(1);
result
}
fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
fn fold_region(&mut self, r: Region<'tcx>) -> Result<Region<'tcx>, Self::Error> {
match r {
ty::ReLateBound(index, br) if *index == self.binder_index => match br.kind {
ty::BrNamed(def_id, _name) => match self.named_parameters.get(&def_id) {
Some(idx) => {
let new_br = ty::BoundRegion { var: br.var, kind: ty::BrAnon(*idx) };
return self.tcx.mk_region(RegionKind::ReLateBound(*index, new_br));
return Ok(self.tcx.mk_region(RegionKind::ReLateBound(*index, new_br)));
}
None => panic!("Missing `BrNamed`."),
},
@ -999,32 +1002,35 @@ impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
self.tcx
}
fn fold_binder<T: TypeFoldable<'tcx>>(&mut self, t: Binder<'tcx, T>) -> Binder<'tcx, T> {
fn fold_binder<T: TypeFoldable<'tcx>>(
&mut self,
t: Binder<'tcx, T>,
) -> Result<Binder<'tcx, T>, Self::Error> {
self.binder_index.shift_in(1);
let result = t.super_fold_with(self);
self.binder_index.shift_out(1);
result
}
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
fn fold_ty(&mut self, t: Ty<'tcx>) -> Result<Ty<'tcx>, Self::Error> {
match *t.kind() {
// FIXME(chalk): currently we convert params to placeholders starting at
// index `0`. To support placeholders, we'll actually need to do a
// first pass to collect placeholders. Then we can insert params after.
ty::Placeholder(_) => unimplemented!(),
ty::Param(param) => match self.list.iter().position(|r| r == &param) {
Some(idx) => self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
Some(idx) => Ok(self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
universe: ty::UniverseIndex::from_usize(0),
name: ty::BoundVar::from_usize(idx),
})),
}))),
None => {
self.list.push(param);
let idx = self.list.len() - 1 + self.next_ty_placeholder;
self.params.insert(idx, param);
self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
Ok(self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
universe: ty::UniverseIndex::from_usize(0),
name: ty::BoundVar::from_usize(idx),
}))
})))
}
},
@ -1032,7 +1038,7 @@ impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
}
}
fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
fn fold_region(&mut self, r: Region<'tcx>) -> Result<Region<'tcx>, Self::Error> {
match r {
// FIXME(chalk) - jackh726 - this currently isn't hit in any tests.
// This covers any region variables in a goal, right?
@ -1042,14 +1048,14 @@ impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
var: ty::BoundVar::from_u32(*idx),
kind: ty::BrAnon(*idx),
};
self.tcx.mk_region(RegionKind::ReLateBound(self.binder_index, br))
Ok(self.tcx.mk_region(RegionKind::ReLateBound(self.binder_index, br)))
}
None => {
let idx = self.named_regions.len() as u32;
let br =
ty::BoundRegion { var: ty::BoundVar::from_u32(idx), kind: ty::BrAnon(idx) };
self.named_regions.insert(_re.def_id, idx);
self.tcx.mk_region(RegionKind::ReLateBound(self.binder_index, br))
Ok(self.tcx.mk_region(RegionKind::ReLateBound(self.binder_index, br)))
}
},
@ -1125,11 +1131,11 @@ impl<'tcx> TypeFolder<'tcx> for RegionsSubstitutor<'tcx> {
self.tcx
}
fn fold_region(&mut self, r: Region<'tcx>) -> Region<'tcx> {
fn fold_region(&mut self, r: Region<'tcx>) -> Result<Region<'tcx>, Self::Error> {
match r {
ty::ReEmpty(ui) => {
assert_eq!(ui.as_usize(), 0);
self.reempty_placeholder
Ok(self.reempty_placeholder)
}
_ => r.super_fold_with(self),