diff --git a/src/fuchsia/mod.rs b/src/fuchsia/mod.rs
index 2be025de53d36..ee193745aa857 100644
--- a/src/fuchsia/mod.rs
+++ b/src/fuchsia/mod.rs
@@ -78,32 +78,10 @@ pub type fsblkcnt_t = c_ulonglong;
 pub type fsfilcnt_t = c_ulonglong;
 pub type rlim_t = c_ulonglong;
 
-// FIXME(fuchsia): why are these uninhabited types? that seems... wrong?
-// Presumably these should be `()` or an `extern type` (when that stabilizes).
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
-}
-#[derive(Debug)]
-pub enum DIR {}
-impl Copy for DIR {}
-impl Clone for DIR {
-    fn clone(&self) -> DIR {
-        *self
-    }
-}
-
-#[derive(Debug)]
-pub enum fpos64_t {} // FIXME(fuchsia): fill this out with a struct
-impl Copy for fpos64_t {}
-impl Clone for fpos64_t {
-    fn clone(&self) -> fpos64_t {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
+    pub enum DIR {}
+    pub enum fpos64_t {} // FIXME(fuchsia): fill this out with a struct
 }
 
 // PUB_STRUCT
@@ -3469,21 +3447,9 @@ fn __MHDR_END(mhdr: *const msghdr) -> *mut c_uchar {
 #[link(name = "fdio")]
 extern "C" {}
 
-#[derive(Debug)]
-pub enum FILE {}
-impl Copy for FILE {}
-impl Clone for FILE {
-    fn clone(&self) -> FILE {
-        *self
-    }
-}
-#[derive(Debug)]
-pub enum fpos_t {} // FIXME(fuchsia): fill this out with a struct
-impl Copy for fpos_t {}
-impl Clone for fpos_t {
-    fn clone(&self) -> fpos_t {
-        *self
-    }
+extern_ty! {
+    pub enum FILE {}
+    pub enum fpos_t {} // FIXME(fuchsia): fill this out with a struct
 }
 
 extern "C" {
diff --git a/src/macros.rs b/src/macros.rs
index 9b700deb45376..ccc35942d3166 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -203,15 +203,25 @@ macro_rules! s_no_extra_traits {
     );
 }
 
-/// Specify that an enum should have no traits that aren't specified in the macro
-/// invocation, i.e. no `Clone` or `Copy`.
-macro_rules! missing {
+/// Create an uninhabited type that can't be constructed. It implements `Debug`, `Clone`,
+/// and `Copy`, but these aren't meaningful for extern types so they should eventually
+/// be removed.
+///
+/// Really what we want here is something that also can't be named without indirection (in
+/// ADTs or function signatures), but this doesn't exist.
+macro_rules! extern_ty {
     ($(
         $(#[$attr:meta])*
         pub enum $i:ident {}
     )*) => ($(
         $(#[$attr])*
-        #[allow(missing_copy_implementations)]
+        // FIXME(1.0): the type is uninhabited so these traits are unreachable and could be
+        // removed.
+        #[::core::prelude::v1::derive(
+            ::core::clone::Clone,
+            ::core::marker::Copy,
+            ::core::fmt::Debug,
+        )]
         pub enum $i { }
     )*);
 }
diff --git a/src/solid/mod.rs b/src/solid/mod.rs
index 40d6a9d348586..37c7fe5f0a342 100644
--- a/src/solid/mod.rs
+++ b/src/solid/mod.rs
@@ -395,21 +395,9 @@ pub const SIGUSR1: c_int = 30;
 pub const SIGUSR2: c_int = 31;
 pub const SIGPWR: c_int = 32;
 
-#[derive(Debug)]
-pub enum FILE {}
-impl Copy for FILE {}
-impl Clone for FILE {
-    fn clone(&self) -> FILE {
-        *self
-    }
-}
-#[derive(Debug)]
-pub enum fpos_t {}
-impl Copy for fpos_t {}
-impl Clone for fpos_t {
-    fn clone(&self) -> fpos_t {
-        *self
-    }
+extern_ty! {
+    pub enum FILE {}
+    pub enum fpos_t {}
 }
 
 extern "C" {
diff --git a/src/unix/aix/powerpc64.rs b/src/unix/aix/powerpc64.rs
index ba4ddc057c40b..1b62859ae1633 100644
--- a/src/unix/aix/powerpc64.rs
+++ b/src/unix/aix/powerpc64.rs
@@ -2,8 +2,7 @@ use crate::off_t;
 use crate::prelude::*;
 
 // Define lock_data_instrumented as an empty enum
-missing! {
-    #[derive(Debug)]
+extern_ty! {
     pub enum lock_data_instrumented {}
 }
 
diff --git a/src/unix/bsd/apple/mod.rs b/src/unix/bsd/apple/mod.rs
index 95201bfbf929e..7b6051d49378c 100644
--- a/src/unix/bsd/apple/mod.rs
+++ b/src/unix/bsd/apple/mod.rs
@@ -175,13 +175,8 @@ pub type copyfile_callback_t = Option<
 pub type attrgroup_t = u32;
 pub type vol_capabilities_set_t = [u32; 4];
 
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
 }
 
 c_enum! {
diff --git a/src/unix/bsd/freebsdlike/dragonfly/mod.rs b/src/unix/bsd/freebsdlike/dragonfly/mod.rs
index 4ade5e7378660..5ff7d9426ee15 100644
--- a/src/unix/bsd/freebsdlike/dragonfly/mod.rs
+++ b/src/unix/bsd/freebsdlike/dragonfly/mod.rs
@@ -45,13 +45,8 @@ pub type vm_map_entry_t = *mut vm_map_entry;
 
 pub type pmap = __c_anonymous_pmap;
 
-#[derive(Debug)]
-pub enum sem {}
-impl Copy for sem {}
-impl Clone for sem {
-    fn clone(&self) -> sem {
-        *self
-    }
+extern_ty! {
+    pub enum sem {}
 }
 
 c_enum! {
diff --git a/src/unix/bsd/freebsdlike/mod.rs b/src/unix/bsd/freebsdlike/mod.rs
index 9a04316808b01..aa6898db20cb7 100644
--- a/src/unix/bsd/freebsdlike/mod.rs
+++ b/src/unix/bsd/freebsdlike/mod.rs
@@ -59,13 +59,8 @@ cfg_if! {
 
 // link.h
 
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
 }
 
 impl siginfo_t {
diff --git a/src/unix/bsd/netbsdlike/mod.rs b/src/unix/bsd/netbsdlike/mod.rs
index 57492258f1687..c377551dffea5 100644
--- a/src/unix/bsd/netbsdlike/mod.rs
+++ b/src/unix/bsd/netbsdlike/mod.rs
@@ -16,21 +16,9 @@ pub type id_t = u32;
 pub type sem_t = *mut sem;
 pub type key_t = c_long;
 
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
-}
-#[derive(Debug)]
-pub enum sem {}
-impl Copy for sem {}
-impl Clone for sem {
-    fn clone(&self) -> sem {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
+    pub enum sem {}
 }
 
 s! {
diff --git a/src/unix/cygwin/mod.rs b/src/unix/cygwin/mod.rs
index 12e30f3f9016c..028ac80cb52d3 100644
--- a/src/unix/cygwin/mod.rs
+++ b/src/unix/cygwin/mod.rs
@@ -28,13 +28,8 @@ pub type nlink_t = c_ushort;
 pub type suseconds_t = c_long;
 pub type useconds_t = c_ulong;
 
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
 }
 
 pub type sigset_t = c_ulong;
@@ -75,13 +70,8 @@ pub type nfds_t = c_uint;
 
 pub type sem_t = *mut sem;
 
-#[derive(Debug)]
-pub enum sem {}
-impl Copy for sem {}
-impl Clone for sem {
-    fn clone(&self) -> sem {
-        *self
-    }
+extern_ty! {
+    pub enum sem {}
 }
 
 pub type tcflag_t = c_uint;
diff --git a/src/unix/haiku/mod.rs b/src/unix/haiku/mod.rs
index 259ad9f2db0f2..6f76e37173fe3 100644
--- a/src/unix/haiku/mod.rs
+++ b/src/unix/haiku/mod.rs
@@ -80,13 +80,8 @@ pub type ACTION = c_int;
 pub type posix_spawnattr_t = *mut c_void;
 pub type posix_spawn_file_actions_t = *mut c_void;
 
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
 }
 
 impl siginfo_t {
diff --git a/src/unix/hurd/mod.rs b/src/unix/hurd/mod.rs
index bb9bd87915b52..3139279187be4 100644
--- a/src/unix/hurd/mod.rs
+++ b/src/unix/hurd/mod.rs
@@ -225,22 +225,9 @@ pub type nl_item = c_int;
 
 pub type iconv_t = *mut c_void;
 
-#[derive(Debug)]
-pub enum fpos64_t {} // FIXME(hurd): fill this out with a struct
-impl Copy for fpos64_t {}
-impl Clone for fpos64_t {
-    fn clone(&self) -> fpos64_t {
-        *self
-    }
-}
-
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
+extern_ty! {
+    pub enum fpos64_t {} // FIXME(hurd): fill this out with a struct
+    pub enum timezone {}
 }
 
 // structs
diff --git a/src/unix/linux_like/emscripten/mod.rs b/src/unix/linux_like/emscripten/mod.rs
index 417e3e593bc5e..91e506c57cc22 100644
--- a/src/unix/linux_like/emscripten/mod.rs
+++ b/src/unix/linux_like/emscripten/mod.rs
@@ -41,13 +41,8 @@ pub type statfs64 = crate::statfs;
 pub type statvfs64 = crate::statvfs;
 pub type dirent64 = crate::dirent;
 
-#[derive(Debug)]
-pub enum fpos64_t {} // FIXME(emscripten): fill this out with a struct
-impl Copy for fpos64_t {}
-impl Clone for fpos64_t {
-    fn clone(&self) -> fpos64_t {
-        *self
-    }
+extern_ty! {
+    pub enum fpos64_t {} // FIXME(emscripten): fill this out with a struct
 }
 
 s! {
diff --git a/src/unix/linux_like/linux/mod.rs b/src/unix/linux_like/linux/mod.rs
index af90bc03ed842..bafdb39ef3c1d 100644
--- a/src/unix/linux_like/linux/mod.rs
+++ b/src/unix/linux_like/linux/mod.rs
@@ -67,8 +67,7 @@ pub type eventfd_t = u64;
 
 cfg_if! {
     if #[cfg(not(target_env = "gnu"))] {
-        missing! {
-            #[derive(Debug)]
+        extern_ty! {
             pub enum fpos64_t {} // FIXME(linux): fill this out with a struct
         }
     }
diff --git a/src/unix/linux_like/mod.rs b/src/unix/linux_like/mod.rs
index 80fa9c176cb8c..7e50c3469e893 100644
--- a/src/unix/linux_like/mod.rs
+++ b/src/unix/linux_like/mod.rs
@@ -8,8 +8,7 @@ pub type timer_t = *mut c_void;
 pub type key_t = c_int;
 pub type id_t = c_uint;
 
-missing! {
-    #[derive(Debug)]
+extern_ty! {
     pub enum timezone {}
 }
 
diff --git a/src/unix/mod.rs b/src/unix/mod.rs
index 7b66aa46baf3e..483bab54b1ee6 100644
--- a/src/unix/mod.rs
+++ b/src/unix/mod.rs
@@ -37,8 +37,7 @@ cfg_if! {
     }
 }
 
-missing! {
-    #[derive(Debug)]
+extern_ty! {
     pub enum DIR {}
 }
 pub type locale_t = *mut c_void;
@@ -585,15 +584,13 @@ cfg_if! {
 
 cfg_if! {
     if #[cfg(not(all(target_os = "linux", target_env = "gnu")))] {
-        missing! {
-            #[derive(Debug)]
+        extern_ty! {
             pub enum fpos_t {} // FIXME(unix): fill this out with a struct
         }
     }
 }
 
-missing! {
-    #[derive(Debug)]
+extern_ty! {
     pub enum FILE {}
 }
 
diff --git a/src/unix/nto/mod.rs b/src/unix/nto/mod.rs
index 3c1f6394d4eae..646d346f12d69 100644
--- a/src/unix/nto/mod.rs
+++ b/src/unix/nto/mod.rs
@@ -72,13 +72,8 @@ pub type sem_t = sync_t;
 
 pub type nl_item = c_int;
 
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
 }
 
 s! {
diff --git a/src/unix/redox/mod.rs b/src/unix/redox/mod.rs
index c46d6b9341401..582b47daf36aa 100644
--- a/src/unix/redox/mod.rs
+++ b/src/unix/redox/mod.rs
@@ -32,13 +32,8 @@ pub type pid_t = usize;
 pub type uid_t = c_int;
 pub type gid_t = c_int;
 
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
 }
 
 s_no_extra_traits! {
diff --git a/src/unix/solarish/mod.rs b/src/unix/solarish/mod.rs
index 5be6129222d00..6805fec9f98ce 100644
--- a/src/unix/solarish/mod.rs
+++ b/src/unix/solarish/mod.rs
@@ -55,22 +55,9 @@ pub type lgrp_view_t = c_uint;
 pub type posix_spawnattr_t = *mut c_void;
 pub type posix_spawn_file_actions_t = *mut c_void;
 
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
-}
-
-#[derive(Debug)]
-pub enum ucred_t {}
-impl Copy for ucred_t {}
-impl Clone for ucred_t {
-    fn clone(&self) -> ucred_t {
-        *self
-    }
+extern_ty! {
+    pub enum timezone {}
+    pub enum ucred_t {}
 }
 
 s! {
diff --git a/src/vxworks/mod.rs b/src/vxworks/mod.rs
index 15bd1b482def2..0fe769169d8f6 100644
--- a/src/vxworks/mod.rs
+++ b/src/vxworks/mod.rs
@@ -4,13 +4,8 @@ use core::ptr::null_mut;
 
 use crate::prelude::*;
 
-#[derive(Debug)]
-pub enum DIR {}
-impl Copy for DIR {}
-impl Clone for DIR {
-    fn clone(&self) -> DIR {
-        *self
-    }
+extern_ty! {
+    pub enum DIR {}
 }
 
 pub type intmax_t = i64;
@@ -95,13 +90,8 @@ pub type sa_family_t = c_uchar;
 // mqueue.h
 pub type mqd_t = c_int;
 
-#[derive(Debug)]
-pub enum _Vx_semaphore {}
-impl Copy for _Vx_semaphore {}
-impl Clone for _Vx_semaphore {
-    fn clone(&self) -> _Vx_semaphore {
-        *self
-    }
+extern_ty! {
+    pub enum _Vx_semaphore {}
 }
 
 impl siginfo_t {
@@ -1065,21 +1055,9 @@ pub const MAP_CONTIG: c_int = 0x0020;
 
 pub const MAP_FAILED: *mut c_void = !0 as *mut c_void;
 
-#[derive(Debug)]
-pub enum FILE {}
-impl Copy for FILE {}
-impl Clone for FILE {
-    fn clone(&self) -> FILE {
-        *self
-    }
-}
-#[derive(Debug)]
-pub enum fpos_t {} // FIXME(vxworks): fill this out with a struct
-impl Copy for fpos_t {}
-impl Clone for fpos_t {
-    fn clone(&self) -> fpos_t {
-        *self
-    }
+extern_ty! {
+    pub enum FILE {}
+    pub enum fpos_t {} // FIXME(vxworks): fill this out with a struct
 }
 
 f! {
diff --git a/src/windows/mod.rs b/src/windows/mod.rs
index 5a00b44ac73aa..9ccdd19f7c682 100644
--- a/src/windows/mod.rs
+++ b/src/windows/mod.rs
@@ -29,14 +29,11 @@ cfg_if! {
 pub type off_t = i32;
 pub type dev_t = u32;
 pub type ino_t = u16;
-#[derive(Debug)]
-pub enum timezone {}
-impl Copy for timezone {}
-impl Clone for timezone {
-    fn clone(&self) -> timezone {
-        *self
-    }
+
+extern_ty! {
+    pub enum timezone {}
 }
+
 pub type time64_t = i64;
 
 pub type SOCKET = crate::uintptr_t;
@@ -246,21 +243,9 @@ pub const SIG_ACK: crate::sighandler_t = 4;
 pub const L_tmpnam: c_uint = 260;
 pub const TMP_MAX: c_uint = 0x7fff_ffff;
 
-#[derive(Debug)]
-pub enum FILE {}
-impl Copy for FILE {}
-impl Clone for FILE {
-    fn clone(&self) -> FILE {
-        *self
-    }
-}
-#[derive(Debug)]
-pub enum fpos_t {} // FIXME(windows): fill this out with a struct
-impl Copy for fpos_t {}
-impl Clone for fpos_t {
-    fn clone(&self) -> fpos_t {
-        *self
-    }
+extern_ty! {
+    pub enum FILE {}
+    pub enum fpos_t {} // FIXME(windows): fill this out with a struct
 }
 
 // Special handling for all print and scan type functions because of https://github.com/rust-lang/libc/issues/2860