From a0e1d509aba0ec14f6e95e1bf720563784ae6771 Mon Sep 17 00:00:00 2001 From: "Felix S. Klock II" Date: Wed, 20 Dec 2017 18:15:33 +0100 Subject: [PATCH] Ensure separate activations only occur for assignments to locals, not projections. Fix #46746. --- src/librustc_mir/dataflow/impls/borrows.rs | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/src/librustc_mir/dataflow/impls/borrows.rs b/src/librustc_mir/dataflow/impls/borrows.rs index c61a57cdda0..a240e869c63 100644 --- a/src/librustc_mir/dataflow/impls/borrows.rs +++ b/src/librustc_mir/dataflow/impls/borrows.rs @@ -361,7 +361,7 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> { } } - mir::StatementKind::Assign(_, ref rhs) => { + mir::StatementKind::Assign(ref lhs, ref rhs) => { // NOTE: if/when the Assign case is revised to inspect // the assigned_place here, make sure to also // re-consider the current implementations of the @@ -382,6 +382,22 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> { panic!("could not find BorrowIndexs for region {:?}", region); }).contains(&index)); sets.gen(&ReserveOrActivateIndex::reserved(*index)); + + if is_activations { + // Issue #46746: Two-phase borrows handles + // stmts of form `Tmp = &mut Borrow` ... + match lhs { + Place::Local(..) => {} // okay + Place::Static(..) => unreachable!(), // (filtered by is_unsafe_place) + Place::Projection(..) => { + // ... can assign into projections, + // e.g. `box (&mut _)`. Current + // conservative solution: force + // immediate activation here. + sets.gen(&ReserveOrActivateIndex::active(*index)); + } + } + } } }