Failing to build on DragonFly BSD because of incorrect casting

[strangelittlemonkey]

zach@test ~/user_test> cargo run
Updating registry https://github.com/rust-lang/crates.io-index
Downloading users v0.8.1
Downloading libc v0.2.48
Compiling libc v0.2.48
error[E0433]: failed to resolve. Use of undeclared type or module mem
--> /home/zach/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.48/src/unix/bsd/freebsdlike/dragonfly/mod.rs:798:33
|
798 | .offset(_CMSG_ALIGN(mem::size_of::<::cmsghdr>()) as isize)
| ^^^ Use of undeclared type or module mem

error[E0433]: failed to resolve. Use of undeclared type or module mem
--> /home/zach/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.48/src/unix/bsd/freebsdlike/dragonfly/mod.rs:802:21
|
802 | _CMSG_ALIGN(mem::size_of::<::cmsghdr>()) + length as usize
| ^^^ Use of undeclared type or module mem

error[E0433]: failed to resolve. Use of undeclared type or module mem
--> /home/zach/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.48/src/unix/bsd/freebsdlike/dragonfly/mod.rs:809:27
|
809 | + _CMSG_ALIGN(mem::size_of::<::cmsghdr>());
| ^^^ Use of undeclared type or module mem

error[E0433]: failed to resolve. Use of undeclared type or module mem
--> /home/zach/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.48/src/unix/bsd/freebsdlike/dragonfly/mod.rs:820:21
|
820 | _CMSG_ALIGN(mem::size_of::<::cmsghdr>()) + _CMSG_ALIGN(length as usize)
| ^^^ Use of undeclared type or module mem

error[E0308]: mismatched types
--> /home/zach/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.48/src/unix/bsd/freebsdlike/dragonfly/mod.rs:802:9
|
801 | pub fn CMSG_LEN(length: ::c_uint) -> ::c_uint {
| -------- expected u32 because of return type
802 | _CMSG_ALIGN(mem::size_of::<::cmsghdr>()) + length as usize
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected u32, found usize

error[E0308]: mismatched types
--> /home/zach/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.48/src/unix/bsd/freebsdlike/dragonfly/mod.rs:808:48
|
808 | let next = cmsg as usize + _CMSG_ALIGN((*cmsg).cmsg_len)
| ^^^^^^^^^^^^^^^^ expected usize, found u32

error[E0308]: mismatched types
--> /home/zach/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.48/src/unix/bsd/freebsdlike/dragonfly/mod.rs:813:42
|
813 | (cmsg as usize + _CMSG_ALIGN((*cmsg).cmsg_len)) as *mut ::cmsghdr
| ^^^^^^^^^^^^^^^^ expected usize, found u32

error[E0308]: mismatched types
--> /home/zach/.cargo/registry/src/github.com-1ecc6299db9ec823/libc-0.2.48/src/unix/bsd/freebsdlike/dragonfly/mod.rs:820:9
|
819 | pub fn CMSG_SPACE(length: ::c_uint) -> ::c_uint {
| -------- expected u32 because of return type
820 | _CMSG_ALIGN(mem::size_of::<::cmsghdr>()) + _CMSG_ALIGN(length as usize)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected u32, found usize

error: aborting due to 8 previous errors

Some errors occurred: E0308, E0433.
For more information about an error, try rustc --explain E0308.
error: Could not compile libc.

To learn more, run the command again with --verbose.

[gnzlbg]

This might be fixed by @asomers PR (#1212 ).

[strangelittlemonkey]

I tested this against master, which includes that PR, and it's not fixed, hence my creation of my PR.

[gnzlbg]

This should be fixed on master, but it would still be really nice if you could pursue your PR about getting libc-test to work there.

I might be landing some simplifications there that might make it easier in case you are low on time.