diff options
| -rw-r--r-- | library/alloc/src/raw_vec.rs | 2 | ||||
| -rw-r--r-- | library/alloc/src/vec/spec_from_iter_nested.rs | 10 |
2 files changed, 9 insertions, 3 deletions
diff --git a/library/alloc/src/raw_vec.rs b/library/alloc/src/raw_vec.rs index 3806bc546ee..8fa0242ca9a 100644 --- a/library/alloc/src/raw_vec.rs +++ b/library/alloc/src/raw_vec.rs @@ -108,7 +108,7 @@ impl<T, A: Allocator> RawVec<T, A> { // to round up a request of less than 8 bytes to at least 8 bytes. // - 4 if elements are moderate-sized (<= 1 KiB). // - 1 otherwise, to avoid wasting too much space for very short Vecs. - const MIN_NON_ZERO_CAP: usize = if mem::size_of::<T>() == 1 { + pub(crate) const MIN_NON_ZERO_CAP: usize = if mem::size_of::<T>() == 1 { 8 } else if mem::size_of::<T>() <= 1024 { 4 diff --git a/library/alloc/src/vec/spec_from_iter_nested.rs b/library/alloc/src/vec/spec_from_iter_nested.rs index 948cf044197..f915ebb86e5 100644 --- a/library/alloc/src/vec/spec_from_iter_nested.rs +++ b/library/alloc/src/vec/spec_from_iter_nested.rs @@ -1,5 +1,8 @@ +use core::cmp; use core::iter::TrustedLen; -use core::ptr::{self}; +use core::ptr; + +use crate::raw_vec::RawVec; use super::{SpecExtend, Vec}; @@ -24,8 +27,11 @@ where None => return Vec::new(), Some(element) => { let (lower, _) = iterator.size_hint(); - let mut vector = Vec::with_capacity(lower.saturating_add(1)); + let initial_capacity = + cmp::max(RawVec::<T>::MIN_NON_ZERO_CAP, lower.saturating_add(1)); + let mut vector = Vec::with_capacity(initial_capacity); unsafe { + // SAFETY: We requested capacity at least 1 ptr::write(vector.as_mut_ptr(), element); vector.set_len(1); } |