From 0801bd1d0ea3858aa6a65ecca4602ae2a15902f9 Mon Sep 17 00:00:00 2001 From: bobtwinkles Date: Wed, 4 Apr 2018 23:08:10 -0400 Subject: [PATCH 1/2] two-phase borrows: support multiple activations in one statement The need for this has arisen since the introduction of two-phase borrows on method autorefs. Fixes 49635 Fixes 49662 --- src/librustc_mir/dataflow/impls/borrows.rs | 22 +++++------- .../two-phase-multiple-activations.rs | 35 +++++++++++++++++++ 2 files changed, 43 insertions(+), 14 deletions(-) create mode 100644 src/test/ui/borrowck/two-phase-multiple-activations.rs diff --git a/src/librustc_mir/dataflow/impls/borrows.rs b/src/librustc_mir/dataflow/impls/borrows.rs index fb3042014df6a..aa991427be093 100644 --- a/src/librustc_mir/dataflow/impls/borrows.rs +++ b/src/librustc_mir/dataflow/impls/borrows.rs @@ -64,10 +64,7 @@ pub struct Borrows<'a, 'gcx: 'tcx, 'tcx: 'a> { assigned_map: FxHashMap, FxHashSet>, /// Locations which activate borrows. - /// NOTE: A given location may activate more than one borrow in the future - /// when more general two-phase borrow support is introduced, but for now we - /// only need to store one borrow index - activation_map: FxHashMap, + activation_map: FxHashMap>, /// Every borrow has a region; this maps each such regions back to /// its borrow-indexes. @@ -174,7 +171,7 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> { idx_vec: IndexVec>, location_map: FxHashMap, assigned_map: FxHashMap, FxHashSet>, - activation_map: FxHashMap, + activation_map: FxHashMap>, region_map: FxHashMap, FxHashSet>, local_map: FxHashMap>, region_span_map: FxHashMap, @@ -211,12 +208,7 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> { let idx = self.idx_vec.push(borrow); self.location_map.insert(location, idx); - // This assert is a good sanity check until more general 2-phase borrow - // support is introduced. See NOTE on the activation_map field for more - assert!(!self.activation_map.contains_key(&activate_location), - "More than one activation introduced at the same location."); - self.activation_map.insert(activate_location, idx); - + insert(&mut self.activation_map, &activate_location, idx); insert(&mut self.assigned_map, assigned_place, idx); insert(&mut self.region_map, ®ion, idx); if let Some(local) = root_local(borrowed_place) { @@ -552,9 +544,11 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> { location: Location) { // Handle activations match self.activation_map.get(&location) { - Some(&activated) => { - debug!("activating borrow {:?}", activated); - sets.gen(&ReserveOrActivateIndex::active(activated)) + Some(activations) => { + for activated in activations { + debug!("activating borrow {:?}", activated); + sets.gen(&ReserveOrActivateIndex::active(*activated)) + } } None => {} } diff --git a/src/test/ui/borrowck/two-phase-multiple-activations.rs b/src/test/ui/borrowck/two-phase-multiple-activations.rs new file mode 100644 index 0000000000000..e1ed41bfb2c64 --- /dev/null +++ b/src/test/ui/borrowck/two-phase-multiple-activations.rs @@ -0,0 +1,35 @@ +// Copyright 2018 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// revisions: lxl nll +//[lxl]compile-flags: -Z borrowck=mir -Z two-phase-borrows +//[nll]compile-flags: -Z borrowck=mir -Z two-phase-borrows -Z nll + +// run-pass + +use std::io::Result; + +struct Foo {} + +pub trait FakeRead { + fn read_to_end(&mut self, buf: &mut Vec) -> Result; +} + +impl FakeRead for Foo { + fn read_to_end(&mut self, buf: &mut Vec) -> Result { + Ok(4) + } +} + +fn main() { + let mut a = Foo {}; + let mut v = Vec::new(); + a.read_to_end(&mut v); +} From bacd1209575b94f9f2347cebf254bf99ce5ab4bc Mon Sep 17 00:00:00 2001 From: bobtwinkles Date: Fri, 6 Apr 2018 15:00:45 -0400 Subject: [PATCH 2/2] Add test from #49736 Fixes #49736 --- src/test/ui/borrowck/two-phase-multi-mut.rs | 26 +++++++++++++++++++ .../ui/borrowck/two-phase-multi-mut.stderr | 23 ++++++++++++++++ 2 files changed, 49 insertions(+) create mode 100644 src/test/ui/borrowck/two-phase-multi-mut.rs create mode 100644 src/test/ui/borrowck/two-phase-multi-mut.stderr diff --git a/src/test/ui/borrowck/two-phase-multi-mut.rs b/src/test/ui/borrowck/two-phase-multi-mut.rs new file mode 100644 index 0000000000000..2b82362885573 --- /dev/null +++ b/src/test/ui/borrowck/two-phase-multi-mut.rs @@ -0,0 +1,26 @@ +// Copyright 2018 The Rust Project Developers. See the COPYRIGHT +// file at the top-level directory of this distribution and at +// http://rust-lang.org/COPYRIGHT. +// +// Licensed under the Apache License, Version 2.0 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![feature(nll)] + +struct Foo { +} + +impl Foo { + fn method(&mut self, foo: &mut Foo) { + } +} + +fn main() { + let mut foo = Foo { }; + foo.method(&mut foo); + //~^ cannot borrow `foo` as mutable more than once at a time + //~^^ cannot borrow `foo` as mutable more than once at a time +} diff --git a/src/test/ui/borrowck/two-phase-multi-mut.stderr b/src/test/ui/borrowck/two-phase-multi-mut.stderr new file mode 100644 index 0000000000000..0c02acf654855 --- /dev/null +++ b/src/test/ui/borrowck/two-phase-multi-mut.stderr @@ -0,0 +1,23 @@ +error[E0499]: cannot borrow `foo` as mutable more than once at a time + --> $DIR/two-phase-multi-mut.rs:23:16 + | +LL | foo.method(&mut foo); + | -----------^^^^^^^^- + | | | + | | second mutable borrow occurs here + | first mutable borrow occurs here + | borrow later used here + +error[E0499]: cannot borrow `foo` as mutable more than once at a time + --> $DIR/two-phase-multi-mut.rs:23:5 + | +LL | foo.method(&mut foo); + | ^^^^^^^^^^^--------^ + | | | + | | first mutable borrow occurs here + | second mutable borrow occurs here + | borrow later used here + +error: aborting due to 2 previous errors + +For more information about this error, try `rustc --explain E0499`.