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Return RootPlace in is_mutable

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This commit is contained in:
Niko Matsakis 2018-04-06 12:35:50 -04:00 • committed by Keith Yeung
parent 8c607eaf94
commit ded0697679
1 changed files with 35 additions and 7 deletions
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42
src/librustc_mir/borrow_check/mod.rs
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@ -1150,13 +1150,14 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
// in order to populate our used_mut set.
if let AggregateKind::Closure(def_id, _) = &**aggregate_kind {
let BorrowCheckResult { used_mut_upvars, .. } = self.tcx.mir_borrowck(*def_id);
debug!("{:?} used_mut_upvars={:?}", def_id, used_mut_upvars);
for field in used_mut_upvars {
match operands[field.index()] {
Operand::Move(Place::Local(local)) => {
self.used_mut.insert(local);
}
Operand::Move(Place::Projection(ref proj)) => {
if let Some(field) = self.is_upvar_field_projection(&proj.base) {
Operand::Move(ref place @ Place::Projection(_)) => {
if let Some(field) = self.is_upvar_field_projection(place) {
self.used_mut_upvars.push(field);
}
}
@ -1697,8 +1698,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
}
}
}
Ok((Place::Projection(ref proj), _mut_allowed)) => {
if let Some(field) = self.is_upvar_field_projection(&proj.base) {
Ok((Place::Projection(_), _mut_allowed)) => {
if let Some(field) = self.is_upvar_field_projection(&place) {
self.used_mut_upvars.push(field);
}
}
@ -1734,8 +1735,8 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
}
}
}
Ok((Place::Projection(ref proj), _mut_allowed)) => {
if let Some(field) = self.is_upvar_field_projection(&proj.base) {
Ok((Place::Projection(_), _mut_allowed)) => {
if let Some(field) = self.is_upvar_field_projection(&place) {
self.used_mut_upvars.push(field);
}
}
@ -1930,7 +1931,34 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
}
(Mutability::Not, LocalMutationIsAllowed::Yes)
| (Mutability::Mut, _) => {
self.is_mutable(&proj.base, is_local_mutation_allowed)
// Subtle: this is an upvar
// reference, so it looks like
// `self.foo` -- we want to double
// check that the context `*self`
// is mutable (i.e., this is not a
// `Fn` closure). But if that
// check succeeds, we want to
// *blame* the mutability on
// `place` (that is,
// `self.foo`). This is used to
// propagate the info about
// whether mutability declarations
// are used outwards, so that we register
// the outer variable as mutable. Otherwise a
// test like this fails to record the `mut`
// as needed:
//
// ```
// fn foo<F: FnOnce()>(_f: F) { }
// fn main() {
// let var = Vec::new();
// foo(move || {
// var.push(1);
// });
// }
// ```
let _ = self.is_mutable(&proj.base, is_local_mutation_allowed)?;
Ok((place, is_local_mutation_allowed))
}
}
} else {