cleanup: Use derived traits as much as possible

Historically Rust hasn't supported derives on packed structs well, and
until recently our automatic derives via `s!` still did not support
these (fixed by 79d1bdb ("Flip `Copy` and `PartialEq, Hash`
derives")). This meant that any packed struct implementing
`extra_traits` had handwritten implementations that are no longer
needed.

There are also a handful of cases that use a handwritten implementation
in order to selectively exclude padding fields. Others don't seem to be
handwritten for any specific reason.

Clean up all of the above by switching from `s_no_extra_traits!` to `s!`
and deleting the handwritten implementations wherever possible. The only
remaining handwritten implementations are those that compare unions with
`unsafe` (which will have to be addressed) or floats.

Note that in some cases, this means we are no longer excluding padding
fields from comparisons. These traits are only usable via references,
not raw pointers; thus, the user has asserted that they are initialized,
and there is no UB in `libc` by reading them. Practically the only way
to know they are initialized is by starting with a zeroed struct, so in
most cases they will have no effect on the results. Whether or not
padding fields are included in handwritten traits is also completely
inconsistent (most include them), so there isn't much predictability
lost here.

The new `Padding` type will also improve the situation here in the
future.

(backport <#4806>)
(cherry picked from commit 141aea1)
[ note that this was very conflict-heavy so the cherry pick differs
  quite a bit from the original commit - Trevor ]

Author: tgross35

src/fuchsia/mod.rs

@@ -880,9 +880,7 @@ s! {
     pub struct pthread_condattr_t {
         size: [u8; crate::__SIZEOF_PTHREAD_CONDATTR_T],
     }
-}
 
-s_no_extra_traits! {
     pub struct sysinfo {
         pub uptime: c_ulong,
         pub loads: [c_ulong; 3],
@@ -969,6 +967,8 @@ s_no_extra_traits! {
         pub nl_groups: u32,
     }
 
+    // FIXME(msrv): suggested method was added in 1.85
+    #[allow(unpredictable_function_pointer_comparisons)]
     pub struct sigevent {
         pub sigev_value: crate::sigval,
         pub sigev_signo: c_int,
@@ -1023,269 +1023,6 @@ s_no_extra_traits! {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "extra_traits")] {
-        impl PartialEq for sysinfo {
-            fn eq(&self, other: &sysinfo) -> bool {
-                self.uptime == other.uptime
-                    && self.loads == other.loads
-                    && self.totalram == other.totalram
-                    && self.freeram == other.freeram
-                    && self.sharedram == other.sharedram
-                    && self.bufferram == other.bufferram
-                    && self.totalswap == other.totalswap
-                    && self.freeswap == other.freeswap
-                    && self.procs == other.procs
-                    && self.pad == other.pad
-                    && self.totalhigh == other.totalhigh
-                    && self.freehigh == other.freehigh
-                    && self.mem_unit == other.mem_unit
-                    && self
-                        .__reserved
-                        .iter()
-                        .zip(other.__reserved.iter())
-                        .all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for sysinfo {}
-        impl hash::Hash for sysinfo {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.uptime.hash(state);
-                self.loads.hash(state);
-                self.totalram.hash(state);
-                self.freeram.hash(state);
-                self.sharedram.hash(state);
-                self.bufferram.hash(state);
-                self.totalswap.hash(state);
-                self.freeswap.hash(state);
-                self.procs.hash(state);
-                self.pad.hash(state);
-                self.totalhigh.hash(state);
-                self.freehigh.hash(state);
-                self.mem_unit.hash(state);
-                self.__reserved.hash(state);
-            }
-        }
-
-        impl PartialEq for sockaddr_un {
-            fn eq(&self, other: &sockaddr_un) -> bool {
-                self.sun_family == other.sun_family
-                    && self
-                        .sun_path
-                        .iter()
-                        .zip(other.sun_path.iter())
-                        .all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for sockaddr_un {}
-        impl hash::Hash for sockaddr_un {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.sun_family.hash(state);
-                self.sun_path.hash(state);
-            }
-        }
-
-        impl PartialEq for sockaddr_storage {
-            fn eq(&self, other: &sockaddr_storage) -> bool {
-                self.ss_family == other.ss_family
-                    && self.__ss_align == other.__ss_align
-                    && self
-                        .__ss_pad2
-                        .iter()
-                        .zip(other.__ss_pad2.iter())
-                        .all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for sockaddr_storage {}
-        impl hash::Hash for sockaddr_storage {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.ss_family.hash(state);
-                self.__ss_align.hash(state);
-                self.__ss_pad2.hash(state);
-            }
-        }
-
-        impl PartialEq for utsname {
-            fn eq(&self, other: &utsname) -> bool {
-                self.sysname
-                    .iter()
-                    .zip(other.sysname.iter())
-                    .all(|(a, b)| a == b)
-                    && self
-                        .nodename
-                        .iter()
-                        .zip(other.nodename.iter())
-                        .all(|(a, b)| a == b)
-                    && self
-                        .release
-                        .iter()
-                        .zip(other.release.iter())
-                        .all(|(a, b)| a == b)
-                    && self
-                        .version
-                        .iter()
-                        .zip(other.version.iter())
-                        .all(|(a, b)| a == b)
-                    && self
-                        .machine
-                        .iter()
-                        .zip(other.machine.iter())
-                        .all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for utsname {}
-        impl hash::Hash for utsname {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.sysname.hash(state);
-                self.nodename.hash(state);
-                self.release.hash(state);
-                self.version.hash(state);
-                self.machine.hash(state);
-            }
-        }
-
-        impl PartialEq for dirent {
-            fn eq(&self, other: &dirent) -> bool {
-                self.d_ino == other.d_ino
-                    && self.d_off == other.d_off
-                    && self.d_reclen == other.d_reclen
-                    && self.d_type == other.d_type
-                    && self
-                        .d_name
-                        .iter()
-                        .zip(other.d_name.iter())
-                        .all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for dirent {}
-        impl hash::Hash for dirent {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.d_ino.hash(state);
-                self.d_off.hash(state);
-                self.d_reclen.hash(state);
-                self.d_type.hash(state);
-                self.d_name.hash(state);
-            }
-        }
-
-        impl PartialEq for dirent64 {
-            fn eq(&self, other: &dirent64) -> bool {
-                self.d_ino == other.d_ino
-                    && self.d_off == other.d_off
-                    && self.d_reclen == other.d_reclen
-                    && self.d_type == other.d_type
-                    && self
-                        .d_name
-                        .iter()
-                        .zip(other.d_name.iter())
-                        .all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for dirent64 {}
-        impl hash::Hash for dirent64 {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.d_ino.hash(state);
-                self.d_off.hash(state);
-                self.d_reclen.hash(state);
-                self.d_type.hash(state);
-                self.d_name.hash(state);
-            }
-        }
-
-        impl PartialEq for mq_attr {
-            fn eq(&self, other: &mq_attr) -> bool {
-                self.mq_flags == other.mq_flags
-                    && self.mq_maxmsg == other.mq_maxmsg
-                    && self.mq_msgsize == other.mq_msgsize
-                    && self.mq_curmsgs == other.mq_curmsgs
-            }
-        }
-        impl Eq for mq_attr {}
-        impl hash::Hash for mq_attr {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.mq_flags.hash(state);
-                self.mq_maxmsg.hash(state);
-                self.mq_msgsize.hash(state);
-                self.mq_curmsgs.hash(state);
-            }
-        }
-
-        impl PartialEq for sockaddr_nl {
-            fn eq(&self, other: &sockaddr_nl) -> bool {
-                self.nl_family == other.nl_family
-                    && self.nl_pid == other.nl_pid
-                    && self.nl_groups == other.nl_groups
-            }
-        }
-        impl Eq for sockaddr_nl {}
-        impl hash::Hash for sockaddr_nl {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.nl_family.hash(state);
-                self.nl_pid.hash(state);
-                self.nl_groups.hash(state);
-            }
-        }
-
-        // FIXME(msrv): suggested method was added in 1.85
-        #[allow(unpredictable_function_pointer_comparisons)]
-        impl PartialEq for sigevent {
-            fn eq(&self, other: &sigevent) -> bool {
-                self.sigev_value == other.sigev_value
-                    && self.sigev_signo == other.sigev_signo
-                    && self.sigev_notify == other.sigev_notify
-                    && self.sigev_notify_function == other.sigev_notify_function
-                    && self.sigev_notify_attributes == other.sigev_notify_attributes
-            }
-        }
-        impl Eq for sigevent {}
-        impl hash::Hash for sigevent {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.sigev_value.hash(state);
-                self.sigev_signo.hash(state);
-                self.sigev_notify.hash(state);
-                self.sigev_notify_function.hash(state);
-                self.sigev_notify_attributes.hash(state);
-            }
-        }
-
-        impl PartialEq for pthread_cond_t {
-            fn eq(&self, other: &pthread_cond_t) -> bool {
-                self.size.iter().zip(other.size.iter()).all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for pthread_cond_t {}
-        impl hash::Hash for pthread_cond_t {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.size.hash(state);
-            }
-        }
-
-        impl PartialEq for pthread_mutex_t {
-            fn eq(&self, other: &pthread_mutex_t) -> bool {
-                self.size.iter().zip(other.size.iter()).all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for pthread_mutex_t {}
-        impl hash::Hash for pthread_mutex_t {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.size.hash(state);
-            }
-        }
-
-        impl PartialEq for pthread_rwlock_t {
-            fn eq(&self, other: &pthread_rwlock_t) -> bool {
-                self.size.iter().zip(other.size.iter()).all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for pthread_rwlock_t {}
-        impl hash::Hash for pthread_rwlock_t {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.size.hash(state);
-            }
-        }
-    }
-}
-
 // PUB_CONST
 
 pub const INT_MIN: c_int = -2147483648;

src/fuchsia/x86_64.rs

@@ -64,9 +64,7 @@ s! {
         __unused1: c_long,
         __unused2: c_long,
     }
-}
 
-s_no_extra_traits! {
     pub struct ucontext_t {
         pub uc_flags: c_ulong,
         pub uc_link: *mut ucontext_t,
@@ -77,36 +75,6 @@ s_no_extra_traits! {
     }
 }
 
-cfg_if! {
-    if #[cfg(feature = "extra_traits")] {
-        impl PartialEq for ucontext_t {
-            fn eq(&self, other: &ucontext_t) -> bool {
-                self.uc_flags == other.uc_flags
-                    && self.uc_link == other.uc_link
-                    && self.uc_stack == other.uc_stack
-                    && self.uc_mcontext == other.uc_mcontext
-                    && self.uc_sigmask == other.uc_sigmask
-                    && self
-                        .__private
-                        .iter()
-                        .zip(other.__private.iter())
-                        .all(|(a, b)| a == b)
-            }
-        }
-        impl Eq for ucontext_t {}
-        impl hash::Hash for ucontext_t {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.uc_flags.hash(state);
-                self.uc_link.hash(state);
-                self.uc_stack.hash(state);
-                self.uc_mcontext.hash(state);
-                self.uc_sigmask.hash(state);
-                self.__private.hash(state);
-            }
-        }
-    }
-}
-
 // offsets in user_regs_structs, from sys/reg.h
 pub const R15: c_int = 0;
 pub const R14: c_int = 1;

src/unix/aix/mod.rs

@@ -544,14 +544,6 @@ s! {
         pub sa_mask: sigset_t,
         pub sa_flags: c_int,
     }
-}
-
-s_no_extra_traits! {
-    pub union __poll_ctl_ext_u {
-        pub addr: *mut c_void,
-        pub data32: u32,
-        pub data: u64,
-    }
 
     pub struct poll_ctl_ext {
         pub version: u8,
@@ -563,6 +555,14 @@ s_no_extra_traits! {
     }
 }
 
+s_no_extra_traits! {
+    pub union __poll_ctl_ext_u {
+        pub addr: *mut c_void,
+        pub data32: u32,
+        pub data: u64,
+    }
+}
+
 cfg_if! {
     if #[cfg(feature = "extra_traits")] {
         impl PartialEq for __poll_ctl_ext_u {
@@ -584,28 +584,6 @@ cfg_if! {
                 }
             }
         }
-
-        impl PartialEq for poll_ctl_ext {
-            fn eq(&self, other: &poll_ctl_ext) -> bool {
-                self.version == other.version
-                    && self.command == other.command
-                    && self.events == other.events
-                    && self.fd == other.fd
-                    && self.reserved64 == other.reserved64
-                    && self.u == other.u
-            }
-        }
-        impl Eq for poll_ctl_ext {}
-        impl hash::Hash for poll_ctl_ext {
-            fn hash<H: hash::Hasher>(&self, state: &mut H) {
-                self.version.hash(state);
-                self.command.hash(state);
-                self.events.hash(state);
-                self.fd.hash(state);
-                self.u.hash(state);
-                self.reserved64.hash(state);
-            }
-        }
     }
 }