Code change:
blksizet on 64-bit FreeBSD is 32 bits, not 64. on FreeBSD x8664 yields: yields: I tracked this down to the type definition, which is unconditionally 32-bit on FreeBSD (see , noting this line: this is unconditionally the definition of on FreeBSD - whether on 32-bit or 64-bit platform.)
Also, is a no-op (two fields of size 0) on 64-bit FreeBSD, the field can be deleted from the structure.

Related discussion:
text: #![stable(feature = "raw_ext", since = "1.1.0")] <del> use os::raw::c_long; use os::unix::raw::{uid_t, gid_t}; </del> <ins> #[stable(feature = "raw_ext", since = "1.1.0")] pub type off_t = i64; #[stable(feature = "raw_ext", since = "1.1.0")] pub type dev_t = u32; #[stable(feature = "raw_ext", since = "1.1.0")] pub type ino_t = u32; #[stable(feature = "raw_ext", since = "1.1.0")] pub type mode_t = u16; #[stable(feature = "raw_ext", since = "1.1.0")] pub type nlink_t = u16; #[stable(feature = "raw_ext", since = "1.1.0")] pub type blksize_t = u32; #[stable(feature = "raw_ext", since = "1.1.0")] pub type blkcnt_t = i64; #[stable(feature = "raw_ext", since = "1.1.0")] pub type fflags_t = u32; </ins> <del> #[stable(feature = "raw_ext", since = "1.1.0")] pub type blkcnt_t = i64; #[stable(feature = "raw_ext", since = "1.1.0")] pub type blksize_t = i64; #[stable(feature = "raw_ext", since = "1.1.0")] pub type dev_t = u32; #[stable(feature = "raw_ext", since = "1.1.0")] pub type fflags_t = u32; #[stable(feature = "raw_ext", since = "1.1.0")] pub type ino_t = u32; #[stable(feature = "raw_ext", since = "1.1.0")] pub type mode_t = u16; #[stable(feature = "raw_ext", since = "1.1.0")] pub type nlink_t = u16; #[stable(feature = "raw_ext", since = "1.1.0")] pub type off_t = i64; #[stable(feature = "raw_ext", since = "1.1.0")] pub type time_t = i64; </del> <ins> #[doc(inline)] pub use self::arch::{stat, time_t}; </ins> <del> #[repr(C)] #[stable(feature = "raw_ext", since = "1.1.0")] pub struct stat { #[stable(feature = "raw_ext", since = "1.1.0")] pub st_dev: dev_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ino: ino_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mode: mode_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_nlink: nlink_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_uid: uid_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_gid: gid_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_rdev: dev_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_atime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_atime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mtime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mtime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ctime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ctime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_size: off_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_blocks: blkcnt_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_blksize: blksize_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_flags: fflags_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_gen: u32, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_lspare: i32, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_birthtime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_birthtime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub __unused: [u8; 2], </del> <ins> #[cfg(target_arch = "x86")] mod arch { use super::{off_t, dev_t, ino_t, mode_t, nlink_t, blksize_t, blkcnt_t, fflags_t}; use os::raw::c_long; use os::unix::raw::{uid_t, gid_t}; #[stable(feature = "raw_ext", since = "1.1.0")] pub type time_t = i32; #[repr(C)] #[stable(feature = "raw_ext", since = "1.1.0")] pub struct stat { #[stable(feature = "raw_ext", since = "1.1.0")] pub st_dev: dev_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ino: ino_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mode: mode_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_nlink: nlink_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_uid: uid_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_gid: gid_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_rdev: dev_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_atime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_atime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mtime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mtime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ctime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ctime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_size: off_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_blocks: blkcnt_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_blksize: blksize_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_flags: fflags_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_gen: u32, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_lspare: i32, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_birthtime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_birthtime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub __unused: [u8; 8], } </ins> } <ins> #[cfg(target_arch = "x86_64")] mod arch { use super::{off_t, dev_t, ino_t, mode_t, nlink_t, blksize_t, blkcnt_t, fflags_t}; use os::raw::c_long; use os::unix::raw::{uid_t, gid_t}; #[stable(feature = "raw_ext", since = "1.1.0")] pub type time_t = i64; #[repr(C)] #[stable(feature = "raw_ext", since = "1.1.0")] pub struct stat { #[stable(feature = "raw_ext", since = "1.1.0")] pub st_dev: dev_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ino: ino_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mode: mode_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_nlink: nlink_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_uid: uid_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_gid: gid_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_rdev: dev_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_atime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_atime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mtime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_mtime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ctime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_ctime_nsec: c_long, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_size: off_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_blocks: blkcnt_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_blksize: blksize_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_flags: fflags_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_gen: u32, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_lspare: i32, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_birthtime: time_t, #[stable(feature = "raw_ext", since = "1.1.0")] pub st_birthtime_nsec: c_long, } } </ins>