2 files changed, 15 insertions, 13 deletions
diff --git a/tvix/nix-compat/src/wire/bytes/mod.rs b/tvix/nix-compat/src/wire/bytes/mod.rs
index 2ed071e37985..74adfb49b6a4 100644
--- a/tvix/nix-compat/src/wire/bytes/mod.rs
+++ b/tvix/nix-compat/src/wire/bytes/mod.rs
@@ -1,9 +1,12 @@
+#[cfg(feature = "async")]
+use std::mem::MaybeUninit;
 use std::{
     io::{Error, ErrorKind},
-    mem::MaybeUninit,
     ops::RangeInclusive,
 };
-use tokio::io::{self, AsyncReadExt, AsyncWriteExt, ReadBuf};
+#[cfg(feature = "async")]
+use tokio::io::ReadBuf;
+use tokio::io::{self, AsyncReadExt, AsyncWriteExt};
 
 pub(crate) mod reader;
 pub use reader::BytesReader;
@@ -11,7 +14,7 @@ mod writer;
 pub use writer::BytesWriter;
 
 /// 8 null bytes, used to write out padding.
-const EMPTY_BYTES: &[u8; 8] = &[0u8; 8];
+pub(crate) const EMPTY_BYTES: &[u8; 8] = &[0u8; 8];
 
 /// The length of the size field, in bytes is always 8.
 const LEN_SIZE: usize = 8;
@@ -33,12 +36,9 @@ const LEN_SIZE: usize = 8;
 ///
 /// This buffers the entire payload into memory,
 /// a streaming version is available at [crate::wire::bytes::BytesReader].
-pub async fn read_bytes<R: ?Sized>(
-    r: &mut R,
-    allowed_size: RangeInclusive<usize>,
-) -> io::Result<Vec<u8>>
+pub async fn read_bytes<R>(r: &mut R, allowed_size: RangeInclusive<usize>) -> io::Result<Vec<u8>>
 where
-    R: AsyncReadExt + Unpin,
+    R: AsyncReadExt + Unpin + ?Sized,
 {
     // read the length field
     let len = r.read_u64_le().await?;
@@ -82,13 +82,14 @@ where
     Ok(buf)
 }
 
-pub(crate) async fn read_bytes_buf<'a, const N: usize, R: ?Sized>(
+#[cfg(feature = "async")]
+pub(crate) async fn read_bytes_buf<'a, const N: usize, R>(
     reader: &mut R,
     buf: &'a mut [MaybeUninit<u8>; N],
     allowed_size: RangeInclusive<usize>,
 ) -> io::Result<&'a [u8]>
 where
-    R: AsyncReadExt + Unpin,
+    R: AsyncReadExt + Unpin + ?Sized,
 {
     assert_eq!(N % 8, 0);
     assert!(*allowed_size.end() <= N);
@@ -135,6 +136,7 @@ where
 }
 
 /// SAFETY: The bytes have to actually be initialized.
+#[cfg(feature = "async")]
 unsafe fn assume_init_bytes(slice: &[MaybeUninit<u8>]) -> &[u8] {
     &*(slice as *const [MaybeUninit<u8>] as *const [u8])
 }
diff --git a/tvix/nix-compat/src/wire/bytes/reader/mod.rs b/tvix/nix-compat/src/wire/bytes/reader/mod.rs
index 6bd376c06fb8..77950496ed6b 100644
--- a/tvix/nix-compat/src/wire/bytes/reader/mod.rs
+++ b/tvix/nix-compat/src/wire/bytes/reader/mod.rs
@@ -109,8 +109,6 @@ where
     }
 
     /// Remaining data length, ie not including data already read.
-    ///
-    /// If the size has not been read yet, this is [None].
     pub fn len(&self) -> u64 {
         match self.state {
             State::Body {
@@ -152,7 +150,7 @@ impl<R: AsyncRead + Unpin, T: Tag> AsyncRead for BytesReader<R, T> {
                     let mut bytes_read = 0;
                     ready!(with_limited(buf, remaining, |buf| {
                         let ret = reader.poll_read(cx, buf);
-                        bytes_read = buf.initialized().len();
+                        bytes_read = buf.filled().len();
                         ret
                     }))?;
 
@@ -414,6 +412,7 @@ mod tests {
     }
 
     /// Read the trailer immediately if there is no payload.
+    #[cfg(feature = "async")]
     #[tokio::test]
     async fn read_trailer_immediately() {
         use crate::nar::wire::PadPar;
@@ -431,6 +430,7 @@ mod tests {
     }
 
     /// Read the trailer even if we only read the exact payload size.
+    #[cfg(feature = "async")]
     #[tokio::test]
     async fn read_exact_trailer() {
         use crate::nar::wire::PadPar;