split out useconds_t from sys_types header

src/header/bits_useconds-t/cbindgen.toml

@@ -0,0 +1,18 @@
+# POSIX header spec: https://pubs.opengroup.org/onlinepubs/009695399/basedefs/sys/types.h.html
+#
+# This type is split out to prevent importing all of sys/types.h into other headers.
+#
+# useconds_t was defined in sys/types.h in an older POSIX standard.
+# relibc currently only uses it in unistd.h for ualarm and usleep.
+#
+# features.h required for deprecated annotation.
+sys_includes = ["features.h"]
+include_guard = "_RELIBC_BITS_USECONDS_T_H"
+language = "C"
+style = "type"
+no_includes = true
+cpp_compat = true
+[export]
+include = ["useconds_t"]
+[enum]
+prefix_with_name = true

src/header/bits_useconds-t/mod.rs

@@ -0,0 +1,6 @@
+use crate::platform::types::c_uint;
+
+/// Used for time in microseconds.
+#[allow(non_camel_case_types)]
+#[deprecated]
+pub type useconds_t = c_uint;

src/header/mod.rs

@@ -53,6 +53,8 @@ pub mod bits_timespec;
 pub mod bits_timeval;
 #[path = "bits_uid-t/mod.rs"]
 pub mod bits_uid_t;
+#[path = "bits_useconds-t/mod.rs"]
+pub mod bits_useconds_t;
 // complex.h implemented in C (currently through openlibm)
 pub mod cpio;
 pub mod crypt;

src/header/sys_types/cbindgen.toml

@@ -2,21 +2,16 @@
 #
 # There are no spec quotations relating to includes
 #
-# - sys/types_internal.h are fundamental C types (which includes stddef.h)
+# - sys/types/internal.h are fundamental C types (which includes stddef.h)
+# - sys/types/internal.h brings in features.h for deprecated annotations for useconds_t
 # - bits/pthread.h is separate for convenience
-# - features.h saves importing separately for any header that imports sys/types.h
-#
-# no default C includes - they cause recursive dependencies and do weird stuff
-no_includes = true
 sys_includes = [
     # Import most necessary, internal types first
     "sys/types/internal.h",
-
     "bits/pthread.h",
-    "features.h",
 ]
-
 include_guard = "_SYS_TYPES_H"
+no_includes = true
 language = "C"
 style = "Tag"
 

src/header/sys_types_internal/cbindgen.toml

@@ -1,4 +1,5 @@
 # stddef.h brings in size_t
+# bits/useconds-t.h brings in features.h for deprecated annotation
 sys_includes = ["stddef.h"]
 after_includes = """
 #include <bits/clock-t.h>
@@ -19,6 +20,7 @@ after_includes = """
 #include <bits/time-t.h>
 #include <bits/timer-t.h>
 #include <bits/uid-t.h>
+#include <bits/useconds-t.h>  // from older POSIX
 """
 include_guard = "_RELIBC_SYS_TYPES_INTERNAL_H"
 language = "C"
@@ -27,7 +29,6 @@ no_includes = true
 
 [export]
 include = [
-  "useconds_t",
   "u_char",
   "uchar",
   "u_short",

src/header/sys_types_internal/mod.rs

@@ -28,10 +28,10 @@ pub use crate::header::{
     bits_timer_t::timer_t,
     bits_uid_t::uid_t,
 };
+#[expect(deprecated)]
+pub use crate::header::bits_useconds_t::useconds_t;
 use crate::platform::types::{c_char, c_longlong, c_uchar, c_uint, c_ulong, c_ulonglong, c_ushort};
 
-pub type useconds_t = c_uint;
-
 pub type u_char = c_uchar;
 pub type uchar = c_uchar;
 pub type u_short = c_ushort;