Merge #183: fixes for last couple months of CI changes

ca3f2ef update and run cargo-public-api again for recent changes (Andrew Poelstra)
e8f126e no-std/alloc: fix a couple "unused import" warnings (Andrew Poelstra)
e4c653a docs: fix a couple unescaped `[` instances which `cargo doc` complains on (Andrew Poelstra)
9ff8288 primitives: remove unused and unconstructable Fe32Iter struct (Andrew Poelstra)
88da498 cargo: whitelist `cfg` flags for latest versions of cargo (Andrew Poelstra)
18bfc5f api: add `Freeze` marker to API files (change in cargo-public-api) (Andrew Poelstra)

Pull request description:

  Clippy, public-api and cargo.

ACKs for top commit:
  clarkmoody:
    ACK ca3f2ef

Tree-SHA512: dfef5071ceaa1303bedffb46cd7a9095533559b58244271ab3428b50afcfd6debb2127ad5164be3e8c13325c3890d75682e9aaf3ed86afdbafb127560a821a18

Cargo.toml

@@ -18,3 +18,6 @@ alloc = []
 
 [target.'cfg(mutate)'.dev-dependencies]
 mutagen = { git = "https://github.com/llogiq/mutagen" }
+
+[lints.rust]
+unexpected_cfgs = { level = "deny", check-cfg = [ 'cfg(bench)', 'cfg(kani)', 'cfg(mutate)' ] }

src/primitives/decode.rs

@@ -720,19 +720,6 @@ impl<'s> ExactSizeIterator for ByteIter<'s> {
     fn len(&self) -> usize { self.iter.len() }
 }
 
-/// An iterator over a parsed HRP string data as field elements.
-pub struct Fe32Iter<'s> {
-    iter: AsciiToFe32Iter<'s>,
-}
-
-impl<'s> Iterator for Fe32Iter<'s> {
-    type Item = Fe32;
-    #[inline]
-    fn next(&mut self) -> Option<Fe32> { self.iter.next() }
-    #[inline]
-    fn size_hint(&self) -> (usize, Option<usize>) { self.iter.size_hint() }
-}
-
 /// Iterator adaptor that maps an iterator of valid bech32 character ASCII bytes to an
 /// iterator of field elements.
 ///

src/primitives/encode.rs

@@ -40,7 +40,6 @@
 //! }
 //! ```
 
-use core::iter::Iterator;
 use core::marker::PhantomData;
 
 use crate::primitives::checksum::HrpFe32Iter;

src/primitives/gf32.rs

@@ -52,7 +52,7 @@ const CHARS_LOWER: [char; 32] = [
 
 /// Mapping from bech32 character (either case) to numeric value.
 ///
-/// E.g., 'z' is CHARS_LOWER[2] and is ASCII value 122 so CHARS_INV[122] == 2
+/// E.g., 'z' is `CHARS_LOWER[2]` and is ASCII value 122 so `CHARS_INV[122]` == 2
 #[rustfmt::skip]
 const CHARS_INV: [i8; 128] = [
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

src/primitives/hrp.rs

@@ -9,7 +9,7 @@
 //!
 //! ref: [BIP-173](https://github.com/bitcoin/bips/blob/master/bip-0173.mediawiki#user-content-Bech32)
 
-#[cfg(feature = "alloc")]
+#[cfg(all(feature = "alloc", not(feature = "std"), not(test)))]
 use alloc::string::String;
 use core::cmp::Ordering;
 use core::fmt::{self, Write};

src/segwit.rs

@@ -44,18 +44,17 @@
 use alloc::{string::String, vec::Vec};
 use core::fmt;
 
+#[cfg(feature = "alloc")]
 use crate::error::write_err;
 use crate::primitives::decode::SegwitCodeLengthError;
 #[cfg(feature = "alloc")]
 use crate::primitives::decode::{SegwitHrpstring, SegwitHrpstringError};
 use crate::primitives::gf32::Fe32;
 use crate::primitives::hrp::Hrp;
 use crate::primitives::iter::{ByteIterExt, Fe32IterExt};
+use crate::primitives::segwit::MAX_STRING_LENGTH;
 #[cfg(feature = "alloc")]
-use crate::primitives::segwit;
-use crate::primitives::segwit::{
-    InvalidWitnessVersionError, WitnessLengthError, MAX_STRING_LENGTH,
-};
+use crate::primitives::segwit::{self, InvalidWitnessVersionError, WitnessLengthError};
 use crate::primitives::{Bech32, Bech32m};
 
 #[rustfmt::skip]                // Keep public re-exports separate.