Deal with deprecation of IntoIter::new.

src/limb.rs

@@ -18,7 +18,10 @@
 //! Limbs ordered least-significant-limb to most-significant-limb. The bits
 //! limbs use the native endianness.
 
-use crate::{c, error, polyfill::ArrayFlatMap};
+use crate::{
+    c, error,
+    polyfill::{self, ArrayFlatMap},
+};
 
 #[cfg(any(test, feature = "alloc"))]
 use crate::bits;
@@ -251,7 +254,7 @@ pub fn big_endian_from_limbs(limbs: &[Limb], out: &mut [u8]) {
 pub fn unstripped_be_bytes(limbs: &[Limb]) -> impl ExactSizeIterator<Item = u8> + Clone + '_ {
     // The unwrap is safe because a slice can never be larger than `usize` bytes.
     ArrayFlatMap::new(limbs.iter().rev().copied(), |limb| {
-        core::array::IntoIter::new(Limb::to_be_bytes(limb))
+        polyfill::array::into_iter(Limb::to_be_bytes(limb))
     })
     .unwrap()
 }

src/polyfill.rs

@@ -27,6 +27,8 @@ pub fn usize_from_u32(x: u32) -> usize {
 #[macro_use]
 mod chunks_fixed;
 
+pub(crate) mod array;
+
 mod array_flat_map;
 pub(crate) mod array_map;
 

src/polyfill/array.rs

@@ -0,0 +1,20 @@
+// Copyright 2022 Brian Smith.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+// TODO: Remove this and use `IntoIterator::into_ter` once MSRV is 1.59.0 or later.
+#[inline(always)]
+pub(crate) fn into_iter<T, const N: usize>(array: [T; N]) -> core::array::IntoIter<T, N> {
+    #[allow(deprecated)]
+    core::array::IntoIter::new(array)
+}

src/polyfill/array_flat_map.rs

@@ -60,6 +60,7 @@ where
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::polyfill;
 
     #[test]
     fn test_array_flat_map() {
@@ -81,7 +82,7 @@ mod tests {
         ];
         TEST_CASES.iter().copied().for_each(|(input, f, expected)| {
             let mapped = ArrayFlatMap::new(input.iter().copied(), |input| {
-                core::array::IntoIter::new(f(input))
+                polyfill::array::into_iter(f(input))
             })
             .unwrap();
             super::super::test::assert_iterator(mapped, expected);
@@ -121,7 +122,7 @@ mod tests {
                 remaining: input_len,
             };
             let mapped = ArrayFlatMap::new(inner, |input| {
-                core::array::IntoIter::new(usize::to_be_bytes(input))
+                polyfill::array::into_iter(usize::to_be_bytes(input))
             });
             assert_eq!(mapped.is_some(), is_some);
             if let Some(mapped) = mapped {

src/rsa/public_exponent.rs

@@ -1,5 +1,5 @@
 use crate::error;
-use crate::polyfill::{ArrayFlatMap, LeadingZerosStripped};
+use crate::polyfill::{self, ArrayFlatMap, LeadingZerosStripped};
 use core::num::NonZeroU64;
 
 /// The exponent `e` of an RSA public key.
@@ -85,7 +85,7 @@ impl PublicExponent {
     pub fn be_bytes(&self) -> impl ExactSizeIterator<Item = u8> + Clone + '_ {
         // The `unwrap()` won't fail as `self.0` is only a few bytes long.
         let bytes = ArrayFlatMap::new(core::iter::once(self.0.get()), |value| {
-            core::array::IntoIter::new(u64::to_be_bytes(value))
+            polyfill::array::into_iter(u64::to_be_bytes(value))
         })
         .unwrap();
         LeadingZerosStripped::new(bytes)