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fix for issue #8636

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This commit is contained in:
Mikhail Modin 2018-07-04 07:45:01 +01:00
parent 6fc21e5576
commit f247a3e490
4 changed files with 356 additions and 16 deletions
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83
src/librustc_mir/borrow_check/places_conflict.rs
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@ -15,6 +15,7 @@ use rustc::hir;
use rustc::mir::{Mir, Place};
use rustc::mir::{Projection, ProjectionElem};
use rustc::ty::{self, TyCtxt};
use std::cmp::max;
pub(super) fn places_conflict<'gcx, 'tcx>(
tcx: TyCtxt<'_, 'gcx, 'tcx>,
@ -394,27 +395,77 @@ fn place_element_conflict<'a, 'gcx: 'tcx, 'tcx>(
| (ProjectionElem::Index(..), ProjectionElem::ConstantIndex { .. })
| (ProjectionElem::Index(..), ProjectionElem::Subslice { .. })
| (ProjectionElem::ConstantIndex { .. }, ProjectionElem::Index(..))
| (ProjectionElem::ConstantIndex { .. }, ProjectionElem::ConstantIndex { .. })
| (ProjectionElem::ConstantIndex { .. }, ProjectionElem::Subslice { .. })
| (ProjectionElem::Subslice { .. }, ProjectionElem::Index(..))
| (ProjectionElem::Subslice { .. }, ProjectionElem::ConstantIndex { .. })
| (ProjectionElem::Subslice { .. }, ProjectionElem::Subslice { .. }) => {
| (ProjectionElem::Subslice { .. }, ProjectionElem::Index(..)) => {
// Array indexes (`a[0]` vs. `a[i]`). These can either be disjoint
// (if the indexes differ) or equal (if they are the same), so this
// is the recursive case that gives "equal *or* disjoint" its meaning.
//
// Note that by construction, MIR at borrowck can't subdivide
// `Subslice` accesses (e.g. `a[2..3][i]` will never be present) - they
// are only present in slice patterns, and we "merge together" nested
// slice patterns. That means we don't have to think about these. It's
// probably a good idea to assert this somewhere, but I'm too lazy.
//
// FIXME(#8636) we might want to return Disjoint if
// both projections are constant and disjoint.
debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY");
debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-INDEX");
Overlap::EqualOrDisjoint
}
(ProjectionElem::ConstantIndex { offset: o1, min_length: _, from_end: false },
ProjectionElem::ConstantIndex { offset: o2, min_length: _, from_end: false })
| (ProjectionElem::ConstantIndex { offset: o1, min_length: _, from_end: true },
ProjectionElem::ConstantIndex {
offset: o2, min_length: _, from_end: true }) => {
if o1 == o2 {
debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX");
Overlap::EqualOrDisjoint
} else {
debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX");
Overlap::Disjoint
}
}
(ProjectionElem::ConstantIndex {
offset: offset_from_begin, min_length: min_length1, from_end: false },
ProjectionElem::ConstantIndex {
offset: offset_from_end, min_length: min_length2, from_end: true })
| (ProjectionElem::ConstantIndex {
offset: offset_from_end, min_length: min_length1, from_end: true },
ProjectionElem::ConstantIndex {
offset: offset_from_begin, min_length: min_length2, from_end: false }) => {
// both patterns matched so it must be at least the greater of the two
let min_length = max(min_length1, min_length2);
// offset_from_end can be in range [1..min_length], -1 for last and min_length
// for first, min_length - offset_from_end gives minimal possible offset from
// the beginning
if *offset_from_begin >= min_length - offset_from_end {
debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX-FE");
Overlap::EqualOrDisjoint
} else {
debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX-FE");
Overlap::Disjoint
}
}
(ProjectionElem::ConstantIndex { offset, min_length: _, from_end: false },
ProjectionElem::Subslice {from, .. })
| (ProjectionElem::Subslice {from, .. },
ProjectionElem::ConstantIndex { offset, min_length: _, from_end: false }) => {
if offset >= from {
debug!(
"place_element_conflict: DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX-SUBSLICE");
Overlap::EqualOrDisjoint
} else {
debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX-SUBSLICE");
Overlap::Disjoint
}
}
(ProjectionElem::ConstantIndex { offset, min_length: _, from_end: true },
ProjectionElem::Subslice {from: _, to })
| (ProjectionElem::Subslice {from: _, to },
ProjectionElem::ConstantIndex { offset, min_length: _, from_end: true }) => {
if offset > to {
debug!("place_element_conflict: \
DISJOINT-OR-EQ-ARRAY-CONSTANT-INDEX-SUBSLICE-FE");
Overlap::EqualOrDisjoint
} else {
debug!("place_element_conflict: DISJOINT-ARRAY-CONSTANT-INDEX-SUBSLICE-FE");
Overlap::Disjoint
}
}
(ProjectionElem::Subslice { .. }, ProjectionElem::Subslice { .. }) => {
debug!("place_element_conflict: DISJOINT-OR-EQ-ARRAY-SUBSLICES");
Overlap::EqualOrDisjoint
}
(ProjectionElem::Deref, _)
| (ProjectionElem::Field(..), _)
| (ProjectionElem::Index(..), _)

33
src/test/run-pass/borrowck/borrowck-slice-pattern-element-loan.rs Normal file
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@ -0,0 +1,33 @@
// Copyright 2012 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//compile-flags: -Z borrowck=mir
#![feature(slice_patterns)]
fn mut_head_tail<'a, A>(v: &'a mut [A]) -> Option<(&'a mut A, &'a mut [A])> {
match *v {
[ref mut head, ref mut tail..] => {
Some((head, tail))
}
[] => None
}
}
fn main() {
let mut v = [1,2,3,4];
match mut_head_tail(&mut v) {
None => {},
Some((h,t)) => {
*h = 1000;
t.reverse();
}
}
}

137
src/test/ui/borrowck/borrowck-slice-pattern-element-loan.rs Normal file
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@ -0,0 +1,137 @@
// Copyright 2014 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//compile-flags: -Z borrowck=mir
#![feature(slice_patterns)]
fn nop(_s: &[& i32]) {}
fn nop_subslice(_s: &[i32]) {}
fn const_index_ok(s: &mut [i32]) {
if let [ref first, ref second, _, ref fourth, ..] = *s {
if let [_, _, ref mut third, ..] = *s {
nop(&[first, second, third, fourth]);
}
}
}
fn const_index_err(s: &mut [i32]) {
if let [ref first, ref second, ..] = *s {
if let [_, ref mut second2, ref mut third, ..] = *s { //~ERROR
nop(&[first, second, second2, third]);
}
}
}
fn const_index_from_end_ok(s: &mut [i32]) {
if let [.., ref fourth, ref third, _, ref first] = *s {
if let [.., ref mut second, _] = *s {
nop(&[first, second, third, fourth]);
}
}
}
fn const_index_from_end_err(s: &mut [i32]) {
if let [.., ref fourth, ref third, _, ref first] = *s {
if let [.., ref mut third2, _, _] = *s { //~ERROR
nop(&[first, third, third2, fourth]);
}
}
}
fn const_index_mixed(s: &mut [i32]) {
if let [.., _, ref from_end4, ref from_end3, _, ref from_end1] = *s {
if let [ref mut from_begin0, ..] = *s {
nop(&[from_begin0, from_end1, from_end3, from_end4]);
}
if let [_, ref mut from_begin1, ..] = *s { //~ERROR
nop(&[from_begin1, from_end1, from_end3, from_end4]);
}
if let [_, _, ref mut from_begin2, ..] = *s { //~ERROR
nop(&[from_begin2, from_end1, from_end3, from_end4]);
}
if let [_, _, _, ref mut from_begin3, ..] = *s { //~ERROR
nop(&[from_begin3, from_end1, from_end3, from_end4]);
}
}
if let [ref from_begin0, ref from_begin1, _, ref from_begin3, _, ..] = *s {
if let [.., ref mut from_end1] = *s {
nop(&[from_begin0, from_begin1, from_begin3, from_end1]);
}
if let [.., ref mut from_end2, _] = *s { //~ERROR
nop(&[from_begin0, from_begin1, from_begin3, from_end2]);
}
if let [.., ref mut from_end3, _, _] = *s { //~ERROR
nop(&[from_begin0, from_begin1, from_begin3, from_end3]);
}
if let [.., ref mut from_end4, _, _, _] = *s { //~ERROR
nop(&[from_begin0, from_begin1, from_begin3, from_end4]);
}
}
}
fn const_index_and_subslice_ok(s: &mut [i32]) {
if let [ref first, ref second, ..] = *s {
if let [_, _, ref mut tail..] = *s {
nop(&[first, second]);
nop_subslice(tail);
}
}
}
fn const_index_and_subslice_err(s: &mut [i32]) {
if let [ref first, ref second, ..] = *s {
if let [_, ref mut tail..] = *s { //~ERROR
nop(&[first, second]);
nop_subslice(tail);
}
}
}
fn const_index_and_subslice_from_end_ok(s: &mut [i32]) {
if let [.., ref second, ref first] = *s {
if let [ref mut tail.., _, _] = *s {
nop(&[first, second]);
nop_subslice(tail);
}
}
}
fn const_index_and_subslice_from_end_err(s: &mut [i32]) {
if let [.., ref second, ref first] = *s {
if let [ref mut tail.., _] = *s { //~ERROR
nop(&[first, second]);
nop_subslice(tail);
}
}
}
fn subslices(s: &mut [i32]) {
if let [_, _, _, ref s1..] = *s {
if let [ref mut s2.., _, _, _] = *s { //~ERROR
nop_subslice(s1);
nop_subslice(s2);
}
}
}
fn main() {
let mut v = [1,2,3,4];
const_index_ok(&mut v);
const_index_err(&mut v);
const_index_from_end_ok(&mut v);
const_index_from_end_err(&mut v);
const_index_and_subslice_ok(&mut v);
const_index_and_subslice_err(&mut v);
const_index_and_subslice_from_end_ok(&mut v);
const_index_and_subslice_from_end_err(&mut v);
subslices(&mut v);
}

119
src/test/ui/borrowck/borrowck-slice-pattern-element-loan.stderr Normal file
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@ -0,0 +1,119 @@
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:28:20
|
LL | if let [ref first, ref second, ..] = *s {
| ---------- immutable borrow occurs here
LL | if let [_, ref mut second2, ref mut third, ..] = *s { //~ERROR
| ^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[first, second, second2, third]);
| ------ borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:44:21
|
LL | if let [.., ref fourth, ref third, _, ref first] = *s {
| --------- immutable borrow occurs here
LL | if let [.., ref mut third2, _, _] = *s { //~ERROR
| ^^^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[first, third, third2, fourth]);
| ----- borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:55:20
|
LL | if let [.., _, ref from_end4, ref from_end3, _, ref from_end1] = *s {
| ------------- immutable borrow occurs here
...
LL | if let [_, ref mut from_begin1, ..] = *s { //~ERROR
| ^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[from_begin1, from_end1, from_end3, from_end4]);
| --------- borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:58:23
|
LL | if let [.., _, ref from_end4, ref from_end3, _, ref from_end1] = *s {
| ------------- immutable borrow occurs here
...
LL | if let [_, _, ref mut from_begin2, ..] = *s { //~ERROR
| ^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[from_begin2, from_end1, from_end3, from_end4]);
| --------- borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:61:26
|
LL | if let [.., _, ref from_end4, ref from_end3, _, ref from_end1] = *s {
| ------------- immutable borrow occurs here
...
LL | if let [_, _, _, ref mut from_begin3, ..] = *s { //~ERROR
| ^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[from_begin3, from_end1, from_end3, from_end4]);
| --------- borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:69:21
|
LL | if let [ref from_begin0, ref from_begin1, _, ref from_begin3, _, ..] = *s {
| --------------- immutable borrow occurs here
...
LL | if let [.., ref mut from_end2, _] = *s { //~ERROR
| ^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[from_begin0, from_begin1, from_begin3, from_end2]);
| ----------- borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:72:21
|
LL | if let [ref from_begin0, ref from_begin1, _, ref from_begin3, _, ..] = *s {
| --------------- immutable borrow occurs here
...
LL | if let [.., ref mut from_end3, _, _] = *s { //~ERROR
| ^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[from_begin0, from_begin1, from_begin3, from_end3]);
| ----------- borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:75:21
|
LL | if let [ref from_begin0, ref from_begin1, _, ref from_begin3, _, ..] = *s {
| --------------- immutable borrow occurs here
...
LL | if let [.., ref mut from_end4, _, _, _] = *s { //~ERROR
| ^^^^^^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[from_begin0, from_begin1, from_begin3, from_end4]);
| ----------- borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:92:20
|
LL | if let [ref first, ref second, ..] = *s {
| ---------- immutable borrow occurs here
LL | if let [_, ref mut tail..] = *s { //~ERROR
| ^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[first, second]);
| ------ borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:110:17
|
LL | if let [.., ref second, ref first] = *s {
| ---------- immutable borrow occurs here
LL | if let [ref mut tail.., _] = *s { //~ERROR
| ^^^^^^^^^^^^ mutable borrow occurs here
LL | nop(&[first, second]);
| ------ borrow later used here
error[E0502]: cannot borrow `s[..]` as mutable because it is also borrowed as immutable
--> $DIR/borrowck-slice-pattern-element-loan.rs:119:17
|
LL | if let [_, _, _, ref s1..] = *s {
| ------ immutable borrow occurs here
LL | if let [ref mut s2.., _, _, _] = *s { //~ERROR
| ^^^^^^^^^^ mutable borrow occurs here
LL | nop_subslice(s1);
| -- borrow later used here
error: aborting due to 11 previous errors
For more information about this error, try `rustc --explain E0502`.