Importing rustc-1.53.0
Bug: 194400612
Change-Id: Id2f38eeabc8325fff960e46b89b1cc7216f5227c
diff --git a/library/core/src/iter/range.rs b/library/core/src/iter/range.rs
index cc80e06..4b293c5 100644
--- a/library/core/src/iter/range.rs
+++ b/library/core/src/iter/range.rs
@@ -3,7 +3,7 @@
use crate::mem;
use crate::ops::{self, Try};
-use super::{FusedIterator, TrustedLen};
+use super::{FusedIterator, TrustedLen, TrustedRandomAccess};
/// Objects that have a notion of *successor* and *predecessor* operations.
///
@@ -493,6 +493,18 @@
)*)
}
+/// Safety: This macro must only be used on types that are `Copy` and result in ranges
+/// which have an exact `size_hint()` where the upper bound must not be `None`.
+macro_rules! unsafe_range_trusted_random_access_impl {
+ ($($t:ty)*) => ($(
+ #[doc(hidden)]
+ #[unstable(feature = "trusted_random_access", issue = "none")]
+ unsafe impl TrustedRandomAccess for ops::Range<$t> {
+ const MAY_HAVE_SIDE_EFFECT: bool = false;
+ }
+ )*)
+}
+
macro_rules! range_incl_exact_iter_impl {
($($t:ty)*) => ($(
#[stable(feature = "inclusive_range", since = "1.26.0")]
@@ -553,6 +565,18 @@
fn max(mut self) -> Option<A> {
self.next_back()
}
+
+ #[inline]
+ unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
+ where
+ Self: TrustedRandomAccess,
+ {
+ // SAFETY: The TrustedRandomAccess contract requires that callers only pass an index
+ // that is in bounds.
+ // Additionally Self: TrustedRandomAccess is only implemented for Copy types
+ // which means even repeated reads of the same index would be safe.
+ unsafe { Step::forward_unchecked(self.start.clone(), idx) }
+ }
}
// These macros generate `ExactSizeIterator` impls for various range types.
@@ -574,6 +598,23 @@
u32
i32
}
+
+unsafe_range_trusted_random_access_impl! {
+ usize u8 u16
+ isize i8 i16
+}
+
+#[cfg(target_pointer_width = "32")]
+unsafe_range_trusted_random_access_impl! {
+ u32 i32
+}
+
+#[cfg(target_pointer_width = "64")]
+unsafe_range_trusted_random_access_impl! {
+ u32 i32
+ u64 i64
+}
+
range_incl_exact_iter_impl! {
u8
i8
