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Fix panic message when RangeFrom index is out of bounds #74510

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Merged
merged 2 commits into from
Jul 25, 2020
Merged

Fix panic message when RangeFrom index is out of bounds #74510

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ce33804
Fix panic message when `RangeFrom` index is out of bounds
LukasKalbertodt Jul 19, 2020
0d64b01
Slightly improve panic messages when range indices are out of bounds
LukasKalbertodt Jul 19, 2020
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25 changes: 19 additions & 6 deletions src/libcore/slice/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2974,8 +2974,15 @@ where
#[inline(never)]
#[cold]
#[track_caller]
fn slice_index_len_fail(index: usize, len: usize) -> ! {
panic!("index {} out of range for slice of length {}", index, len);
fn slice_start_index_len_fail(index: usize, len: usize) -> ! {
panic!("range start index {} out of range for slice of length {}", index, len);
}

#[inline(never)]
#[cold]
#[track_caller]
fn slice_end_index_len_fail(index: usize, len: usize) -> ! {
panic!("range end index {} out of range for slice of length {}", index, len);
}

#[inline(never)]
Expand Down Expand Up @@ -3160,7 +3167,7 @@ unsafe impl<T> SliceIndex<[T]> for ops::Range<usize> {
if self.start > self.end {
slice_index_order_fail(self.start, self.end);
} else if self.end > slice.len() {
slice_index_len_fail(self.end, slice.len());
slice_end_index_len_fail(self.end, slice.len());
}
unsafe { &*self.get_unchecked(slice) }
}
Expand All @@ -3170,7 +3177,7 @@ unsafe impl<T> SliceIndex<[T]> for ops::Range<usize> {
if self.start > self.end {
slice_index_order_fail(self.start, self.end);
} else if self.end > slice.len() {
slice_index_len_fail(self.end, slice.len());
slice_end_index_len_fail(self.end, slice.len());
}
unsafe { &mut *self.get_unchecked_mut(slice) }
}
Expand Down Expand Up @@ -3241,12 +3248,18 @@ unsafe impl<T> SliceIndex<[T]> for ops::RangeFrom<usize> {

#[inline]
fn index(self, slice: &[T]) -> &[T] {
(self.start..slice.len()).index(slice)
if self.start > slice.len() {
slice_start_index_len_fail(self.start, slice.len());
}
unsafe { &*self.get_unchecked(slice) }
}

#[inline]
fn index_mut(self, slice: &mut [T]) -> &mut [T] {
(self.start..slice.len()).index_mut(slice)
if self.start > slice.len() {
slice_start_index_len_fail(self.start, slice.len());
}
unsafe { &mut *self.get_unchecked_mut(slice) }
}
}

Expand Down
2 changes: 1 addition & 1 deletion src/libcore/tests/slice.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1088,7 +1088,7 @@ mod slice_index {

good: data[6..] == [];
bad: data[7..];
message: "but ends at"; // perhaps not ideal
message: "out of range";
}

in mod rangeto_len {
Expand Down
6 changes: 3 additions & 3 deletions src/test/codegen/issue-69101-bounds-check.rs
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Expand Up @@ -12,7 +12,7 @@
// CHECK-LABEL: @already_sliced_no_bounds_check
#[no_mangle]
pub fn already_sliced_no_bounds_check(a: &[u8], b: &[u8], c: &mut [u8]) {
// CHECK: slice_index_len_fail
// CHECK: slice_end_index_len_fail
// CHECK-NOT: panic_bounds_check
let _ = (&a[..2048], &b[..2048], &mut c[..2048]);
for i in 0..1024 {
Expand All @@ -23,7 +23,7 @@ pub fn already_sliced_no_bounds_check(a: &[u8], b: &[u8], c: &mut [u8]) {
// CHECK-LABEL: @already_sliced_no_bounds_check_exact
#[no_mangle]
pub fn already_sliced_no_bounds_check_exact(a: &[u8], b: &[u8], c: &mut [u8]) {
// CHECK: slice_index_len_fail
// CHECK: slice_end_index_len_fail
// CHECK-NOT: panic_bounds_check
let _ = (&a[..1024], &b[..1024], &mut c[..1024]);
for i in 0..1024 {
Expand All @@ -35,7 +35,7 @@ pub fn already_sliced_no_bounds_check_exact(a: &[u8], b: &[u8], c: &mut [u8]) {
// CHECK-LABEL: @already_sliced_bounds_check
#[no_mangle]
pub fn already_sliced_bounds_check(a: &[u8], b: &[u8], c: &mut [u8]) {
// CHECK: slice_index_len_fail
// CHECK: slice_end_index_len_fail
// CHECK: panic_bounds_check
let _ = (&a[..1023], &b[..2048], &mut c[..2048]);
for i in 0..1024 {
Expand Down