diff options
| -rw-r--r-- | library/core/src/iter/adapters/fuse.rs | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/library/core/src/iter/adapters/fuse.rs b/library/core/src/iter/adapters/fuse.rs index ae074065315..7a852c2cb9d 100644 --- a/library/core/src/iter/adapters/fuse.rs +++ b/library/core/src/iter/adapters/fuse.rs @@ -1,6 +1,8 @@ use crate::intrinsics; use crate::iter::adapters::{zip::try_get_unchecked, InPlaceIterable, SourceIter}; -use crate::iter::{DoubleEndedIterator, ExactSizeIterator, FusedIterator, TrustedRandomAccess}; +use crate::iter::{ + DoubleEndedIterator, ExactSizeIterator, FusedIterator, TrustedLen, TrustedRandomAccess, +}; use crate::ops::Try; /// An iterator that yields `None` forever after the underlying iterator @@ -182,8 +184,19 @@ where } } +#[unstable(feature = "trusted_len", issue = "37572")] +// SAFETY: `TrustedLen` requires that an accurate length is reported via `size_hint()`. As `Fuse` +// is just forwarding this to the wrapped iterator `I` this property is preserved and it is safe to +// implement `TrustedLen` here. +unsafe impl<I> TrustedLen for Fuse<I> where I: TrustedLen {} + #[doc(hidden)] #[unstable(feature = "trusted_random_access", issue = "none")] +// SAFETY: `TrustedRandomAccess` requires that `size_hint()` must be exact and cheap to call, and +// `Iterator::__iterator_get_unchecked()` must be implemented accordingly. +// +// This is safe to implement as `Fuse` is just forwarding these to the wrapped iterator `I`, which +// preserves these properties. unsafe impl<I> TrustedRandomAccess for Fuse<I> where I: TrustedRandomAccess, |