diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/coroutine/by_move_body.rs | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs b/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs index 4e3e70bdafe..1cc0a5026d1 100644 --- a/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs +++ b/compiler/rustc_mir_transform/src/coroutine/by_move_body.rs @@ -1,3 +1,8 @@ +//! A MIR pass which duplicates a coroutine's body and removes any derefs which +//! would be present for upvars that are taken by-ref. The result of which will +//! be a coroutine body that takes all of its upvars by-move, and which we stash +//! into the `CoroutineInfo` for all coroutines returned by coroutine-closures. + use rustc_data_structures::fx::FxIndexSet; use rustc_hir as hir; use rustc_middle::mir::visit::MutVisitor; @@ -87,11 +92,16 @@ impl<'tcx> MutVisitor<'tcx> for MakeByMoveBody<'tcx> { && self.by_ref_fields.contains(&idx) { let (begin, end) = place.projection[1..].split_first().unwrap(); + // FIXME(async_closures): I'm actually a bit surprised to see that we always + // initially deref the by-ref upvars. If this is not actually true, then we + // will at least get an ICE that explains why this isn't true :^) assert_eq!(*begin, mir::ProjectionElem::Deref); + // Peel one ref off of the ty. + let peeled_ty = ty.builtin_deref(true).unwrap().ty; *place = mir::Place { local: place.local, projection: self.tcx.mk_place_elems_from_iter( - [mir::ProjectionElem::Field(idx, ty.builtin_deref(true).unwrap().ty)] + [mir::ProjectionElem::Field(idx, peeled_ty)] .into_iter() .chain(end.iter().copied()), ), @@ -101,6 +111,7 @@ impl<'tcx> MutVisitor<'tcx> for MakeByMoveBody<'tcx> { } fn visit_local_decl(&mut self, local: mir::Local, local_decl: &mut mir::LocalDecl<'tcx>) { + // Replace the type of the self arg. if local == ty::CAPTURE_STRUCT_LOCAL { local_decl.ty = self.by_move_coroutine_ty; } |