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Mark migration code that relies on Deref unreachable

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This commit is contained in:
Aman Arora 2021-02-04 19:55:16 -05:00
parent 319f1aba62
commit 5b54640128
1 changed files with 8 additions and 39 deletions
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47
compiler/rustc_typeck/src/check/upvar.rs
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@ -698,8 +698,8 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
/// freeing up memory).
///
/// The way this function works is at a given call it looks at type `base_path_ty` of some base
/// path say P and then vector of projection slices which represent the different captures
/// starting off of P.
/// path say P and then list of projection slices which represent the different captures moved
/// into the closure starting off of P.
///
/// This will make more sense with an example:
///
@ -842,23 +842,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
// `captured_projs.first().unwrap()` safely.
// - All entries in `captured_projs` have atleast one projection.
// Therefore we can call `captured_projs.first().unwrap().first().unwrap()` safely.
ty::Adt(def, _) if def.is_box() => {
// We must deref to access paths on top of a Box.
assert!(
captured_projs
.iter()
.all(|projs| matches!(projs.first().unwrap().kind, ProjectionKind::Deref))
);
let next_ty = captured_projs.first().unwrap().first().unwrap().ty;
let captured_projs = captured_projs.iter().map(|projs| &projs[1..]).collect();
self.has_significant_drop_outside_of_captures(
closure_def_id,
closure_span,
next_ty,
captured_projs,
)
}
// We don't capture derefs in case of move captures, which would have be applied to
// access any further paths.
ty::Adt(def, _) if def.is_box() => unreachable!(),
ty::Ref(..) => unreachable!(),
ty::RawPtr(..) => unreachable!(),
ty::Adt(def, substs) => {
// Multi-varaint enums are captured in entirety,
@ -929,27 +918,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
})
}
ty::Ref(_, deref_ty, _) => {
// Only Derefs can be applied to a Ref
assert!(
captured_projs
.iter()
.all(|projs| matches!(projs.first().unwrap().kind, ProjectionKind::Deref))
);
let captured_projs = captured_projs.iter().map(|projs| &projs[1..]).collect();
self.has_significant_drop_outside_of_captures(
closure_def_id,
closure_span,
deref_ty,
captured_projs,
)
}
// Unsafe Ptrs are captured in their entirety, which would've have been handled in
// the case of single empty slice in `captured_projs`.
ty::RawPtr(..) => unreachable!(),
// Anything else would be completely captured and therefore handled already.
_ => unreachable!(),
}
}