From 84dc48522d71ec4531219927155b20c2eadbae70 Mon Sep 17 00:00:00 2001 From: Matthew Jasper Date: Tue, 31 Jul 2018 21:35:22 +0100 Subject: [PATCH] Allow borrow conflicts for promoted length 0 arrays --- .../borrow_check/places_conflict.rs | 7 ++++++ .../promotable-mutable-zst-doesnt-conflict.rs | 23 +++++++++++++++++++ 2 files changed, 30 insertions(+) create mode 100644 src/test/ui/nll/promotable-mutable-zst-doesnt-conflict.rs diff --git a/src/librustc_mir/borrow_check/places_conflict.rs b/src/librustc_mir/borrow_check/places_conflict.rs index c44af003654..640ae31d45b 100644 --- a/src/librustc_mir/borrow_check/places_conflict.rs +++ b/src/librustc_mir/borrow_check/places_conflict.rs @@ -329,6 +329,13 @@ fn place_element_conflict<'a, 'gcx: 'tcx, 'tcx>( } (Place::Promoted(p1), Place::Promoted(p2)) => { if p1.0 == p2.0 { + if let ty::TyArray(_, size) = p1.1.sty { + if size.unwrap_usize(tcx) == 0 { + // Ignore conflicts with promoted [T; 0]. + debug!("place_element_conflict: IGNORE-LEN-0-PROMOTED"); + return Overlap::Disjoint; + } + } // the same promoted - base case, equal debug!("place_element_conflict: DISJOINT-OR-EQ-PROMOTED"); Overlap::EqualOrDisjoint diff --git a/src/test/ui/nll/promotable-mutable-zst-doesnt-conflict.rs b/src/test/ui/nll/promotable-mutable-zst-doesnt-conflict.rs new file mode 100644 index 00000000000..be385569612 --- /dev/null +++ b/src/test/ui/nll/promotable-mutable-zst-doesnt-conflict.rs @@ -0,0 +1,23 @@ +// 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. + +// Check that mutable promoted length zero arrays don't check for conflicting +// access + +// run-pass + +#![feature(nll)] + +pub fn main() { + let mut x: Vec<&[i32; 0]> = Vec::new(); + for i in 0..10 { + x.push(&[]); + } +} -- 2.44.0