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Check for exhaustion in SliceIndex for RangeInclusive

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This commit is contained in:
Josh Stone 2020-10-20 17:18:08 -07:00
parent 9fd79a3904
commit 9202fbdbdb
5 changed files with 85 additions and 20 deletions
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29
library/alloc/tests/str.rs
View File

@ -529,6 +529,13 @@ fn test_slice_fail() {
message: "out of bounds";
}
in mod rangeinclusive_len {
data: "abcdef";
good: data[0..=5] == "abcdef";
bad: data[0..=6];
message: "out of bounds";
}
in mod range_len_len {
data: "abcdef";
good: data[6..6] == "";
@ -544,6 +551,28 @@ fn test_slice_fail() {
}
}
panic_cases! {
in mod rangeinclusive_exhausted {
data: "abcdef";
good: data[0..=5] == "abcdef";
good: data[{
let mut iter = 0..=5;
iter.by_ref().count(); // exhaust it
iter
}] == "";
// 0..=6 is out of bounds before exhaustion, so it
// stands to reason that it still would be after.
bad: data[{
let mut iter = 0..=6;
iter.by_ref().count(); // exhaust it
iter
}];
message: "out of bounds";
}
}
panic_cases! {
in mod range_neg_width {
data: "abcdef";

14
library/core/src/ops/range.rs
View File

@ -446,6 +446,20 @@ pub fn into_inner(self) -> (Idx, Idx) {
}
}
impl RangeInclusive<usize> {
/// Converts to an exclusive `Range` for `SliceIndex` implementations.
/// The caller is responsible for dealing with `end == usize::MAX`.
#[inline]
pub(crate) fn into_slice_range(self) -> Range<usize> {
// If we're not exhausted, we want to simply slice `start..end + 1`.
// If we are exhausted, then slicing with `end + 1..end + 1` gives us an
// empty range that is still subject to bounds-checks for that endpoint.
let exclusive_end = self.end + 1;
let start = if self.exhausted { exclusive_end } else { self.start };
start..exclusive_end
}
}
#[stable(feature = "inclusive_range", since = "1.26.0")]
impl<Idx: fmt::Debug> fmt::Debug for RangeInclusive<Idx> {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {

16
library/core/src/slice/index.rs
View File

@ -376,28 +376,24 @@ unsafe impl<T> SliceIndex<[T]> for ops::RangeInclusive<usize> {
#[inline]
fn get(self, slice: &[T]) -> Option<&[T]> {
if *self.end() == usize::MAX { None } else { (*self.start()..self.end() + 1).get(slice) }
if *self.end() == usize::MAX { None } else { self.into_slice_range().get(slice) }
}
#[inline]
fn get_mut(self, slice: &mut [T]) -> Option<&mut [T]> {
if *self.end() == usize::MAX {
None
} else {
(*self.start()..self.end() + 1).get_mut(slice)
}
if *self.end() == usize::MAX { None } else { self.into_slice_range().get_mut(slice) }
}
#[inline]
unsafe fn get_unchecked(self, slice: *const [T]) -> *const [T] {
// SAFETY: the caller has to uphold the safety contract for `get_unchecked`.
unsafe { (*self.start()..self.end() + 1).get_unchecked(slice) }
unsafe { self.into_slice_range().get_unchecked(slice) }
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: *mut [T]) -> *mut [T] {
// SAFETY: the caller has to uphold the safety contract for `get_unchecked_mut`.
unsafe { (*self.start()..self.end() + 1).get_unchecked_mut(slice) }
unsafe { self.into_slice_range().get_unchecked_mut(slice) }
}
#[inline]
@ -405,7 +401,7 @@ fn index(self, slice: &[T]) -> &[T] {
if *self.end() == usize::MAX {
slice_end_index_overflow_fail();
}
(*self.start()..self.end() + 1).index(slice)
self.into_slice_range().index(slice)
}
#[inline]
@ -413,7 +409,7 @@ fn index_mut(self, slice: &mut [T]) -> &mut [T] {
if *self.end() == usize::MAX {
slice_end_index_overflow_fail();
}
(*self.start()..self.end() + 1).index_mut(slice)
self.into_slice_range().index_mut(slice)
}
}

16
library/core/src/str/traits.rs
View File

@ -398,39 +398,35 @@ unsafe impl SliceIndex<str> for ops::RangeInclusive<usize> {
type Output = str;
#[inline]
fn get(self, slice: &str) -> Option<&Self::Output> {
if *self.end() == usize::MAX { None } else { (*self.start()..self.end() + 1).get(slice) }
if *self.end() == usize::MAX { None } else { self.into_slice_range().get(slice) }
}
#[inline]
fn get_mut(self, slice: &mut str) -> Option<&mut Self::Output> {
if *self.end() == usize::MAX {
None
} else {
(*self.start()..self.end() + 1).get_mut(slice)
}
if *self.end() == usize::MAX { None } else { self.into_slice_range().get_mut(slice) }
}
#[inline]
unsafe fn get_unchecked(self, slice: *const str) -> *const Self::Output {
// SAFETY: the caller must uphold the safety contract for `get_unchecked`.
unsafe { (*self.start()..self.end() + 1).get_unchecked(slice) }
unsafe { self.into_slice_range().get_unchecked(slice) }
}
#[inline]
unsafe fn get_unchecked_mut(self, slice: *mut str) -> *mut Self::Output {
// SAFETY: the caller must uphold the safety contract for `get_unchecked_mut`.
unsafe { (*self.start()..self.end() + 1).get_unchecked_mut(slice) }
unsafe { self.into_slice_range().get_unchecked_mut(slice) }
}
#[inline]
fn index(self, slice: &str) -> &Self::Output {
if *self.end() == usize::MAX {
str_index_overflow_fail();
}
(*self.start()..self.end() + 1).index(slice)
self.into_slice_range().index(slice)
}
#[inline]
fn index_mut(self, slice: &mut str) -> &mut Self::Output {
if *self.end() == usize::MAX {
str_index_overflow_fail();
}
(*self.start()..self.end() + 1).index_mut(slice)
self.into_slice_range().index_mut(slice)
}
}

30
library/core/tests/slice.rs
View File

@ -1341,6 +1341,14 @@ fn simple() {
message: "out of range";
}
in mod rangeinclusive_len {
data: [0, 1, 2, 3, 4, 5];
good: data[0..=5] == [0, 1, 2, 3, 4, 5];
bad: data[0..=6];
message: "out of range";
}
in mod range_len_len {
data: [0, 1, 2, 3, 4, 5];
@ -1358,6 +1366,28 @@ fn simple() {
}
}
panic_cases! {
in mod rangeinclusive_exhausted {
data: [0, 1, 2, 3, 4, 5];
good: data[0..=5] == [0, 1, 2, 3, 4, 5];
good: data[{
let mut iter = 0..=5;
iter.by_ref().count(); // exhaust it
iter
}] == [];
// 0..=6 is out of range before exhaustion, so it
// stands to reason that it still would be after.
bad: data[{
let mut iter = 0..=6;
iter.by_ref().count(); // exhaust it
iter
}];
message: "out of range";
}
}
panic_cases! {
in mod range_neg_width {
data: [0, 1, 2, 3, 4, 5];