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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
24 changed files with 387 additions and 305 deletions
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36
compiler/rustc_middle/src/ty/util.rs
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@@ -605,13 +605,13 @@ impl<'tcx> TypeFolder<'tcx> for OpaqueTypeExpander<'tcx> {
self.tcx
}
fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
fn fold_ty(&mut self, t: Ty<'tcx>) -> Result<Ty<'tcx>, Self::Error> {
if let ty::Opaque(def_id, substs) = t.kind {
self.expand_opaque_ty(def_id, substs).unwrap_or(t)
Ok(self.expand_opaque_ty(def_id, substs).unwrap_or(t))
} else if t.has_opaque_types() {
t.super_fold_with(self)
} else {
t
Ok(t)
}
}
}
@@ -1046,25 +1046,31 @@ pub fn fold_list<'tcx, F, T>(
list: &'tcx ty::List<T>,
folder: &mut F,
intern: impl FnOnce(TyCtxt<'tcx>, &[T]) -> &'tcx ty::List<T>,
) -> &'tcx ty::List<T>
) -> Result<&'tcx ty::List<T>, F::Error>
where
F: TypeFolder<'tcx>,
T: TypeFoldable<'tcx> + PartialEq + Copy,
{
let mut iter = list.iter();
// Look for the first element that changed
if let Some((i, new_t)) = iter.by_ref().enumerate().find_map(|(i, t)| {
let new_t = t.fold_with(folder);
if new_t == t { None } else { Some((i, new_t)) }
match iter.by_ref().enumerate().find_map(|(i, t)| match t.fold_with(folder) {
Ok(new_t) if new_t == t => None,
new_t => Some((i, new_t)),
}) {
// An element changed, prepare to intern the resulting list
let mut new_list = SmallVec::<[_; 8]>::with_capacity(list.len());
new_list.extend_from_slice(&list[..i]);
new_list.push(new_t);
new_list.extend(iter.map(|t| t.fold_with(folder)));
intern(folder.tcx(), &new_list)
} else {
list
Some((i, Ok(new_t))) => {
// An element changed, prepare to intern the resulting list
let mut new_list = SmallVec::<[_; 8]>::with_capacity(list.len());
new_list.extend_from_slice(&list[..i]);
new_list.push(new_t);
for t in iter {
new_list.push(t.fold_with(folder)?)
}
Ok(intern(folder.tcx(), &new_list))
}
Some((_, Err(err))) => {
return Err(err);
}
None => Ok(list),
}
}