I got the same problem.
> starting phase `build'
> Error: CliError { error: Some(failed to select a version for `clang-sys`.
> ... required by package `bindgen v0.58.1`
> ... which is depended on by `dav1d-sys v0.3.4`
> ... which is depended on by `rav1e v0.4.1
> (/tmp/guix-build-rav1e-0.4.1.drv-0/rav1e-0.4.1)`
> versions that meet the requirements `^1` are: 1.0.0
>
> the package `clang-sys` links to the native library `clang`, but it conflicts
> with a previous package which links to `clang` as well:
> package `clang-sys v0.29.3`
> ... which is depended on by `bindgen v0.54.1`
> ... which is depended on by `aom-sys v0.2.1`
> ... which is depended on by `rav1e v0.4.1
> (/tmp/guix-build-rav1e-0.4.1.drv-0/rav1e-0.4.1)`
>
> failed to select a version for `clang-sys` which could resolve this
> conflict), exit_code: 101 }
> error: in phase 'build': uncaught exception:
> %exception #<&invoke-error program: "cargo" arguments: ("cinstall"
> "--release"
> "--prefix=/gnu/store/83mfvccy0szp2v9v2qk8xf5wz867ndnx-rav1e-0.4.1")
> exit-status: 1 term-signal: #f stop-signal: #f>
> phase `build' failed after 0.7 seconds
> command "cargo" "cinstall" "--release"
> "--prefix=/gnu/store/83mfvccy0szp2v9v2qk8xf5wz867ndnx-rav1e-0.4.1" failed
> with status 1
