Documenting nix v0.26.1 (/tmp/cirrus-ci-build)
    Finished dev [unoptimized + debuginfo] target(s) in 0.96s
$TOOL clippy $ZFLAGS --target $TARGET --all-targets -- -D warnings
    Checking nix v0.26.1 (/tmp/cirrus-ci-build)
error: this argument is a mutable reference, but not used mutably
    --> src/sys/socket/mod.rs:2208:33
     |
2208 | pub fn recv(sockfd: RawFd, buf: &mut [u8], flags: MsgFlags) -> Result<usize> {
     |                                 ^^^^^^^^^ help: consider changing to: `&[u8]`
     |
     = warning: changing this function will impact semver compatibility
     = note: this is cfg-gated and may require further changes
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_ref_mut
     = note: `-D clippy::needless-pass-by-ref-mut` implied by `-D warnings`

error: this argument is a mutable reference, but not used mutably
    --> src/sys/socket/mod.rs:2228:10
     |
2228 |     buf: &mut [u8],
     |          ^^^^^^^^^ help: consider changing to: `&[u8]`
     |
     = warning: changing this function will impact semver compatibility
     = note: this is cfg-gated and may require further changes
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_ref_mut

error: this argument is a mutable reference, but not used mutably
  --> src/sys/uio.rs:30:37
   |
30 | pub fn readv<Fd: AsFd>(fd: Fd, iov: &mut [IoSliceMut<'_>]) -> Result<usize> {
   |                                     ^^^^^^^^^^^^^^^^^^^^^ help: consider changing to: `&[IoSliceMut<'_>]`
   |
   = warning: changing this function will impact semver compatibility
   = note: this is cfg-gated and may require further changes
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_ref_mut

error: could not compile `nix` (lib) due to 3 previous errors
warning: build failed, waiting for other jobs to finish...
error: this argument is a mutable reference, but not used mutably
    --> src/sys/socket/mod.rs:2208:33
     |
2208 | pub fn recv(sockfd: RawFd, buf: &mut [u8], flags: MsgFlags) -> Result<usize> {
     |                                 ^^^^^^^^^ help: consider changing to: `&[u8]`
     |
     = warning: changing this function will impact semver compatibility
     = note: this is cfg-gated and may require further changes
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_ref_mut
note: the lint level is defined here
    --> src/lib.rs:46:24
     |
46   | #![cfg_attr(test, deny(warnings))]
     |                        ^^^^^^^^
     = note: `#[deny(clippy::needless_pass_by_ref_mut)]` implied by `#[deny(warnings)]`

error: could not compile `nix` (lib test) due to 3 previous errors

Exit status: 101