Move `std` impl from `lib.rs` to `bridge.rs`

This reduces the number of compilation conditions.

io/src/bridge.rs

@@ -254,3 +254,35 @@ impl<T: super::Write> super::Write for ToStd<T> {
         self.0.write_all(buf)
     }
 }
+
+impl<R: std::io::Read> super::Read for std::io::BufReader<R> {
+    #[inline]
+    fn read(&mut self, buf: &mut [u8]) -> super::Result<usize> { Ok(std::io::Read::read(self, buf)?) }
+}
+
+impl<R: std::io::Read> super::BufRead for std::io::BufReader<R> {
+    #[inline]
+    fn fill_buf(&mut self) -> super::Result<&[u8]> { Ok(std::io::BufRead::fill_buf(self)?) }
+
+    #[inline]
+    fn consume(&mut self, amount: usize) { std::io::BufRead::consume(self, amount) }
+}
+
+impl std::io::Write for super::Sink {
+    #[inline]
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> { Ok(buf.len()) }
+
+    #[inline]
+    fn write_all(&mut self, _: &[u8]) -> std::io::Result<()> { Ok(()) }
+
+    #[inline]
+    fn flush(&mut self) -> std::io::Result<()> { Ok(()) }
+}
+
+impl<W: std::io::Write> super::Write for std::io::BufWriter<W> {
+    #[inline]
+    fn write(&mut self, buf: &[u8]) -> super::Result<usize> { Ok(std::io::Write::write(self, buf)?) }
+
+    #[inline]
+    fn flush(&mut self) -> super::Result<()> { Ok(std::io::Write::flush(self)?) }
+}

io/src/lib.rs

@@ -163,12 +163,6 @@ impl Read for &[u8] {
     }
 }
 
-#[cfg(feature = "std")]
-impl<R: std::io::Read> Read for std::io::BufReader<R> {
-    #[inline]
-    fn read(&mut self, buf: &mut [u8]) -> Result<usize> { Ok(std::io::Read::read(self, buf)?) }
-}
-
 impl BufRead for &[u8] {
     #[inline]
     fn fill_buf(&mut self) -> Result<&[u8]> { Ok(self) }
@@ -178,15 +172,6 @@ impl BufRead for &[u8] {
     fn consume(&mut self, amount: usize) { *self = &self[amount..] }
 }
 
-#[cfg(feature = "std")]
-impl<R: std::io::Read> BufRead for std::io::BufReader<R> {
-    #[inline]
-    fn fill_buf(&mut self) -> Result<&[u8]> { Ok(std::io::BufRead::fill_buf(self)?) }
-
-    #[inline]
-    fn consume(&mut self, amount: usize) { std::io::BufRead::consume(self, amount) }
-}
-
 /// Wraps an in memory reader providing the `position` function.
 pub struct Cursor<T> {
     inner: T,
@@ -301,15 +286,6 @@ impl<'a> Write for &'a mut [u8] {
     fn flush(&mut self) -> Result<()> { Ok(()) }
 }
 
-#[cfg(feature = "std")]
-impl<W: std::io::Write> Write for std::io::BufWriter<W> {
-    #[inline]
-    fn write(&mut self, buf: &[u8]) -> Result<usize> { Ok(std::io::Write::write(self, buf)?) }
-
-    #[inline]
-    fn flush(&mut self) -> Result<()> { Ok(std::io::Write::flush(self)?) }
-}
-
 /// A sink to which all writes succeed. See [`std::io::Sink`] for more info.
 ///
 /// Created using `io::sink()`.
@@ -326,18 +302,6 @@ impl Write for Sink {
     fn flush(&mut self) -> Result<()> { Ok(()) }
 }
 
-#[cfg(feature = "std")]
-impl std::io::Write for Sink {
-    #[inline]
-    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> { Ok(buf.len()) }
-
-    #[inline]
-    fn write_all(&mut self, _: &[u8]) -> std::io::Result<()> { Ok(()) }
-
-    #[inline]
-    fn flush(&mut self) -> std::io::Result<()> { Ok(()) }
-}
-
 /// Returns a sink to which all writes succeed. See [`std::io::sink`] for more info.
 #[inline]
 pub fn sink() -> Sink { Sink }