digest: move std::io stuff to digest-io (#1809)

The `digest-io` crate is added in
RustCrypto/utils#1172

Author: newpavlov

.github/workflows/digest.yml

@@ -60,5 +60,4 @@ jobs:
       - run: cargo test
       - run: cargo test --features dev
       - run: cargo test --features alloc
-      - run: cargo test --features std
       - run: cargo test --all-features

crypto/Cargo.toml

@@ -26,7 +26,6 @@ universal-hash = { version = "0.6.0-rc.0", path = "../universal-hash", optional
 
 [features]
 std = [
-    "digest/std",
     "elliptic-curve/std",
     "signature/std",
 ]

digest/CHANGELOG.md

@@ -15,10 +15,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Removed
 - `Mac::new`, `Mac::new_from_slice`, and `Mac::generate_key` methods ([#1173])
+- `HashReader` and `HashWriter` are moved to the `digest-io` crate ([#1809])
+- Removed `io::Write/Read` implementations in favor of the `digest_io::IoWrapper` type ([#1809])
 
 [#1173]: https://github.com/RustCrypto/traits/pull/1173
 [#1334]: https://github.com/RustCrypto/traits/pull/1334
 [#1759]: https://github.com/RustCrypto/traits/pull/1759
+[#1809]: https://github.com/RustCrypto/traits/pull/1809
 
 ## 0.10.7 (2023-05-19)
 ### Changed

digest/Cargo.toml

@@ -31,7 +31,6 @@ os_rng = ["crypto-common/rand_core", "rand_core"]
 oid = ["const-oid"]
 zeroize = ["dep:zeroize", "block-buffer?/zeroize"]
 alloc = []
-std = ["alloc"]
 dev = ["blobby"]
 
 [package.metadata.docs.rs]

digest/src/core_api/rt_variable.rs

@@ -184,17 +184,3 @@ where
         })
     }
 }
-
-#[cfg(feature = "std")]
-impl<T: VariableOutputCore> std::io::Write for RtVariableCoreWrapper<T> {
-    #[inline]
-    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
-        Update::update(self, buf);
-        Ok(buf.len())
-    }
-
-    #[inline]
-    fn flush(&mut self) -> std::io::Result<()> {
-        Ok(())
-    }
-}

digest/src/core_api/wrapper.rs

@@ -220,20 +220,6 @@ where
     }
 }
 
-#[cfg(feature = "std")]
-impl<T: BufferKindUser + UpdateCore> std::io::Write for CoreWrapper<T> {
-    #[inline]
-    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
-        Update::update(self, buf);
-        Ok(buf.len())
-    }
-
-    #[inline]
-    fn flush(&mut self) -> std::io::Result<()> {
-        Ok(())
-    }
-}
-
 /// A proxy trait to a core type implemented by [`CoreWrapper`]
 // TODO: replace with an inherent associated type on stabilization:
 // https://github.com/rust-lang/rust/issues/8995

digest/src/core_api/xof_reader.rs

@@ -36,18 +36,6 @@ where
     }
 }
 
-#[cfg(feature = "std")]
-impl<T> std::io::Read for XofReaderCoreWrapper<T>
-where
-    T: XofReaderCore,
-{
-    #[inline]
-    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
-        XofReader::read(self, buf);
-        Ok(buf.len())
-    }
-}
-
 impl<T: XofReaderCore> Drop for XofReaderCoreWrapper<T> {
     #[inline]
     fn drop(&mut self) {

digest/src/hashreader.rs

@@ -18,9 +18,12 @@
 //!   Usually they should not be used in application-level code.
 //!
 //! Additionally hash functions implement traits from the standard library:
-//! [`Default`], [`Clone`], [`Write`][std::io::Write]. The latter is
-//! feature-gated behind `std` feature, which is usually enabled by default
-//! by hash implementation crates.
+//! [`Default`] and [`Clone`].
+//!
+//! This crate does not provide any implementations of the `io::Read/Write` traits,
+//! see the [`digest-io`] crate for `std::io`-compatibility wrappers.
+//!
+//! [`digest-io`]: https://docs.rs/digest-io
 
 #![no_std]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
@@ -35,9 +38,6 @@
 #[macro_use]
 extern crate alloc;
 
-#[cfg(feature = "std")]
-extern crate std;
-
 #[cfg(feature = "rand_core")]
 pub use crypto_common::rand_core;
 
@@ -303,12 +303,3 @@ impl fmt::Display for InvalidBufferSize {
 }
 
 impl core::error::Error for InvalidBufferSize {}
-
-#[cfg(feature = "std")]
-mod hashwriter;
-#[cfg(feature = "std")]
-pub use hashwriter::HashWriter;
-#[cfg(feature = "std")]
-mod hashreader;
-#[cfg(feature = "std")]
-pub use hashreader::HashReader;