unix: annotate unstable *COUNT constants

These caused SemVer issues. They can change in upstream releases. This
patch aleviates that. It links to usage advice.

Author: dybucc

src/unix/bsd/apple/mod.rs

@@ -3736,7 +3736,11 @@ pub const MNT_NOWAIT: c_int = 2;
 
 // <mach/thread_policy.h>
 pub const THREAD_STANDARD_POLICY: c_int = 1;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_STANDARD_POLICY_COUNT: c_int = 0;
+
 pub const THREAD_EXTENDED_POLICY: c_int = 1;
 pub const THREAD_TIME_CONSTRAINT_POLICY: c_int = 2;
 pub const THREAD_PRECEDENCE_POLICY: c_int = 3;
@@ -3798,7 +3802,11 @@ pub const VM_PAGE_QUERY_PAGE_CS_NX: i32 = 0x400;
 
 // mach/task_info.h
 pub const TASK_THREAD_TIMES_INFO: u32 = 3;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const HOST_CPU_LOAD_INFO_COUNT: u32 = 4;
+
 pub const MACH_TASK_BASIC_INFO: u32 = 20;
 
 pub const MACH_PORT_NULL: i32 = 0;
@@ -3861,7 +3869,10 @@ pub const COPYFILE_STATE_DST_BSIZE: c_int = 12;
 pub const COPYFILE_STATE_BSIZE: c_int = 13;
 
 // <sys/attr.h>
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const ATTR_BIT_MAP_COUNT: c_ushort = 5;
+
 pub const FSOPT_NOFOLLOW: u32 = 0x1;
 pub const FSOPT_NOFOLLOW_ANY: u32 = 0x800;
 pub const FSOPT_REPORT_FULLSIZE: u32 = 0x4;
@@ -4032,36 +4043,73 @@ const fn __DARWIN_ALIGN32(p: usize) -> usize {
     (p + __DARWIN_ALIGNBYTES32) & !__DARWIN_ALIGNBYTES32
 }
 
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_EXTENDED_POLICY_COUNT: mach_msg_type_number_t =
     (size_of::<thread_extended_policy_data_t>() / size_of::<integer_t>()) as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_TIME_CONSTRAINT_POLICY_COUNT: mach_msg_type_number_t =
     (size_of::<thread_time_constraint_policy_data_t>() / size_of::<integer_t>())
         as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_PRECEDENCE_POLICY_COUNT: mach_msg_type_number_t =
     (size_of::<thread_precedence_policy_data_t>() / size_of::<integer_t>())
         as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_AFFINITY_POLICY_COUNT: mach_msg_type_number_t =
     (size_of::<thread_affinity_policy_data_t>() / size_of::<integer_t>()) as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_BACKGROUND_POLICY_COUNT: mach_msg_type_number_t =
     (size_of::<thread_background_policy_data_t>() / size_of::<integer_t>())
         as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_LATENCY_QOS_POLICY_COUNT: mach_msg_type_number_t =
     (size_of::<thread_latency_qos_policy_data_t>() / size_of::<integer_t>())
         as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_THROUGHPUT_QOS_POLICY_COUNT: mach_msg_type_number_t =
     (size_of::<thread_throughput_qos_policy_data_t>() / size_of::<integer_t>())
         as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_BASIC_INFO_COUNT: mach_msg_type_number_t =
     (size_of::<thread_basic_info_data_t>() / size_of::<integer_t>()) as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_IDENTIFIER_INFO_COUNT: mach_msg_type_number_t =
     (size_of::<thread_identifier_info_data_t>() / size_of::<integer_t>()) as mach_msg_type_number_t;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const THREAD_EXTENDED_INFO_COUNT: mach_msg_type_number_t =
     (size_of::<thread_extended_info_data_t>() / size_of::<integer_t>()) as mach_msg_type_number_t;
 
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const TASK_THREAD_TIMES_INFO_COUNT: u32 =
     (size_of::<task_thread_times_info_data_t>() / size_of::<natural_t>()) as u32;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const MACH_TASK_BASIC_INFO_COUNT: u32 =
     (size_of::<mach_task_basic_info_data_t>() / size_of::<natural_t>()) as u32;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const HOST_VM_INFO64_COUNT: mach_msg_type_number_t =
     (size_of::<vm_statistics64_data_t>() / size_of::<integer_t>()) as mach_msg_type_number_t;
 

src/unix/linux_like/android/mod.rs

@@ -1569,6 +1569,9 @@ pub const NFNL_SUBSYS_CTNETLINK_TIMEOUT: c_int = 8;
 pub const NFNL_SUBSYS_CTHELPER: c_int = 9;
 pub const NFNL_SUBSYS_NFTABLES: c_int = 10;
 pub const NFNL_SUBSYS_NFT_COMPAT: c_int = 11;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const NFNL_SUBSYS_COUNT: c_int = 12;
 
 pub const NFNL_MSG_BATCH_BEGIN: c_int = NLMSG_MIN_TYPE;

src/unix/linux_like/linux/mod.rs

@@ -1678,6 +1678,9 @@ pub const NFNL_SUBSYS_CTHELPER: c_int = 9;
 pub const NFNL_SUBSYS_NFTABLES: c_int = 10;
 pub const NFNL_SUBSYS_NFT_COMPAT: c_int = 11;
 pub const NFNL_SUBSYS_HOOK: c_int = 12;
+
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const NFNL_SUBSYS_COUNT: c_int = 13;
 
 pub const NFNL_MSG_BATCH_BEGIN: c_int = crate::NLMSG_MIN_TYPE;

src/unix/solarish/illumos.rs

@@ -186,7 +186,10 @@ pub const PRIV_USER: c_uint = PRIV_DEBUG
     | PRIV_AWARE_RESET
     | PRIV_PFEXEC;
 
+/// This symbol is prone to change across releases upstream.
+/// See the [usage guidelines](crate::#usage-guidelines) for details and use.
 pub const LGRP_RSRC_COUNT: crate::lgrp_rsrc_t = 2;
+
 pub const LGRP_RSRC_CPU: crate::lgrp_rsrc_t = 0;
 pub const LGRP_RSRC_MEM: crate::lgrp_rsrc_t = 1;