Inline io module in io crate root

Its not immediately obvious why we nest the whole `io` code in an `io`
submodule within `lib.rs`. As far as I can tell we can inline it and
re-export from `rust-bitcoin` same as we do for our other dependencies.

This change would effect other users of the crate but since the `io`
crate is unreleased this effects no-one except us.

bitcoin/Cargo.toml

@@ -27,8 +27,8 @@ bitcoinconsensus-std = ["bitcoinconsensus/std", "std"]
 # The no-std feature doesn't disable std - you need to turn off the std feature for that by disabling default.
 # Instead no-std enables additional features required for this crate to be usable without std.
 # As a result, both can be enabled without conflict.
-std = ["secp256k1/std", "bitcoin-io/std", "hashes/std", "bech32/std", "internals/std", "hex/std"]
+std = ["secp256k1/std", "io/std", "hashes/std", "bech32/std", "internals/std", "hex/std"]
-no-std = ["hashes/alloc", "hashes/io", "bitcoin-io/alloc", "bech32/alloc", "secp256k1/alloc", "hex/alloc"]
+no-std = ["hashes/alloc", "hashes/io", "io/alloc", "bech32/alloc", "secp256k1/alloc", "hex/alloc"]
 
 [package.metadata.docs.rs]
 all-features = true
@@ -40,10 +40,9 @@ hex = { package = "hex-conservative", version = "0.1.1", default-features = fals
 bech32 = { version = "0.10.0-beta", default-features = false }
 hashes = { package = "bitcoin_hashes", version = "0.13.0", default-features = false }
 secp256k1 = { version = "0.28.0", default-features = false, features = ["hashes"] }
+io = { package = "bitcoin-io", version = "0.1", default-features = false }
 hex_lit = "0.1.1"
 
-bitcoin-io = { version = "0.1", default-features = false }
-
 base64 = { version = "0.21.3", optional = true }
 # Only use this feature for no-std builds, otherwise use bitcoinconsensus-std.
 bitcoinconsensus = { version = "0.20.2-0.5.0", default-features = false, optional = true }

bitcoin/src/lib.rs

@@ -74,6 +74,9 @@ pub extern crate hashes;
 /// Re-export the `hex-conservative` crate.
 pub extern crate hex;
 
+/// Re-export the `bitcoin-io` crate.
+pub extern crate io;
+
 /// Rust wrapper library for Pieter Wuille's libsecp256k1.  Implements ECDSA and BIP 340 signatures
 /// for the SECG elliptic curve group secp256k1 and related utilities.
 pub extern crate secp256k1;
@@ -113,7 +116,6 @@ pub mod sign_message;
 pub mod string;
 pub mod taproot;
 
-use bitcoin_io::io;
 
 #[rustfmt::skip]                // Keep public re-exports separate.
 #[doc(inline)]

hashes/embedded/src/main.rs

@@ -10,7 +10,7 @@ extern crate bitcoin_hashes;
 #[cfg(feature = "alloc")] use alloc::string::ToString;
 
 use bitcoin_hashes::{sha256, Hash, HashEngine};
-use bitcoin_io::io::Write;
+use bitcoin_io::Write;
 use core::str::FromStr;
 use cortex_m_rt::entry;
 use cortex_m_semihosting::{debug, hprintln};

hashes/src/impls.rs

@@ -66,7 +66,7 @@ impl_write!(
 
 #[cfg(test)]
 mod tests {
-    use bitcoin_io::io::Write;
+    use bitcoin_io::Write;
 
     use crate::{hash160, hmac, ripemd160, sha1, sha256, sha256d, sha512, siphash24, Hash};
 

io/src/lib.rs

@@ -24,7 +24,6 @@ mod macros;
 
 /// Standard I/O stream definitions which are API-equivalent to `std`'s `io` module. See
 /// [`std::io`] for more info.
-pub mod io {
 #[cfg(any(feature = "alloc", feature = "std"))]
 use alloc::boxed::Box;
 use core::convert::TryInto;
@@ -351,4 +350,4 @@ pub mod io {
 }
 /// Returns a sink to which all writes succeed. See [`std::io::sink`] for more info.
 pub fn sink() -> Sink { Sink }
-}
+

io/src/macros.rs

@@ -11,13 +11,13 @@
 #[cfg(not(feature = "std"))]
 macro_rules! impl_write {
     ($ty: ty, $write_fn: expr, $flush_fn: expr $(, $bounded_ty: ident : $bounds: path),*) => {
-        impl<$($bounded_ty: $bounds),*> $crate::io::Write for $ty {
+        impl<$($bounded_ty: $bounds),*> $crate::Write for $ty {
             #[inline]
-            fn write(&mut self, buf: &[u8]) -> $crate::io::Result<usize> {
+            fn write(&mut self, buf: &[u8]) -> $crate::Result<usize> {
                 $write_fn(self, buf)
             }
             #[inline]
-            fn flush(&mut self) -> $crate::io::Result<()> {
+            fn flush(&mut self) -> $crate::Result<()> {
                 $flush_fn(self)
             }
         }