Change weak! and linkat! to macros 2.0

`weak!` is needed in a test in another module. With macros
1.0, importing `weak!` would require reordering module
declarations in `std/src/lib.rs`, which is a bit too
evil.

library/std/src/sys/unix/android.rs

@@ -21,7 +21,7 @@
 use libc::{c_int, c_void, sighandler_t, size_t, ssize_t};
 use libc::{ftruncate, pread, pwrite};
 
-use super::{cvt, cvt_r};
+use super::{cvt, cvt_r, weak::weak};
 use crate::io;
 
 // The `log2` and `log2f` functions apparently appeared in android-18, or at

library/std/src/sys/unix/fs.rs

@@ -12,6 +12,15 @@ use crate::sys::time::SystemTime;
 use crate::sys::{cvt, cvt_r};
 use crate::sys_common::{AsInner, FromInner};
 
+#[cfg(any(
+    all(target_os = "linux", target_env = "gnu"),
+    target_os = "macos",
+    target_os = "ios",
+))]
+use crate::sys::weak::syscall;
+#[cfg(target_os = "macos")]
+use crate::sys::weak::weak;
+
 use libc::{c_int, mode_t};
 
 #[cfg(any(

library/std/src/sys/unix/kernel_copy.rs

@@ -61,6 +61,7 @@ use crate::process::{ChildStderr, ChildStdin, ChildStdout};
 use crate::ptr;
 use crate::sync::atomic::{AtomicBool, AtomicU8, Ordering};
 use crate::sys::cvt;
+use crate::sys::weak::syscall;
 use libc::{EBADF, EINVAL, ENOSYS, EOPNOTSUPP, EOVERFLOW, EPERM, EXDEV};
 
 #[cfg(test)]

library/std/src/sys/unix/os.rs

@@ -23,6 +23,9 @@ use crate::sys::memchr;
 use crate::sys_common::rwlock::{StaticRWLock, StaticRWLockReadGuard};
 use crate::vec;
 
+#[cfg(all(target_env = "gnu", not(target_os = "vxworks")))]
+use crate::sys::weak::weak;
+
 use libc::{c_char, c_int, c_void};
 
 const TMPBUF_SZ: usize = 128;

library/std/src/sys/unix/process/process_unix.rs

@@ -9,6 +9,14 @@ use crate::sys;
 use crate::sys::cvt;
 use crate::sys::process::process_common::*;
 
+#[cfg(any(
+    target_os = "macos",
+    target_os = "freebsd",
+    all(target_os = "linux", target_env = "gnu"),
+    all(target_os = "linux", target_env = "musl"),
+))]
+use crate::sys::weak::weak;
+
 #[cfg(target_os = "vxworks")]
 use libc::RTP_ID as pid_t;
 

library/std/src/sys/unix/rand.rs

@@ -25,6 +25,9 @@ mod imp {
     use crate::fs::File;
     use crate::io::Read;
 
+    #[cfg(any(target_os = "linux", target_os = "android"))]
+    use crate::sys::weak::syscall;
+
     #[cfg(any(target_os = "linux", target_os = "android"))]
     fn getrandom(buf: &mut [u8]) -> libc::ssize_t {
         // A weak symbol allows interposition, e.g. for perf measurements that want to
@@ -108,6 +111,7 @@ mod imp {
     use crate::fs::File;
     use crate::io::Read;
     use crate::sys::os::errno;
+    use crate::sys::weak::weak;
     use libc::{c_int, c_void, size_t};
 
     fn getentropy_fill_bytes(v: &mut [u8]) -> bool {

library/std/src/sys/unix/thread.rs

@@ -7,6 +7,8 @@ use crate::ptr;
 use crate::sys::{os, stack_overflow};
 use crate::time::Duration;
 
+#[cfg(any(target_os = "linux", target_os = "solaris", target_os = "illumos"))]
+use crate::sys::weak::weak;
 #[cfg(not(any(target_os = "l4re", target_os = "vxworks")))]
 pub const DEFAULT_MIN_STACK_SIZE: usize = 2 * 1024 * 1024;
 #[cfg(target_os = "l4re")]

library/std/src/sys/unix/weak.rs

@@ -26,8 +26,11 @@ use crate::marker;
 use crate::mem;
 use crate::sync::atomic::{self, AtomicUsize, Ordering};
 
-macro_rules! weak {
+// Temporary null documentation to work around #57569 until the fix is beta
+#[cfg_attr(bootstrap, doc = "")]
+pub(crate) macro weak {
     (fn $name:ident($($t:ty),*) -> $ret:ty) => (
+        #[allow(non_upper_case_globals)]
         static $name: crate::sys::weak::Weak<unsafe extern "C" fn($($t),*) -> $ret> =
             crate::sys::weak::Weak::new(concat!(stringify!($name), '\0'));
     )
@@ -100,8 +103,10 @@ unsafe fn fetch(name: &str) -> usize {
     libc::dlsym(libc::RTLD_DEFAULT, name.as_ptr()) as usize
 }
 
+// Temporary null documentation to work around #57569 until the fix is beta
+#[cfg_attr(bootstrap, doc = "")]
 #[cfg(not(any(target_os = "linux", target_os = "android")))]
-macro_rules! syscall {
+pub(crate) macro syscall {
     (fn $name:ident($($arg_name:ident: $t:ty),*) -> $ret:ty) => (
         unsafe fn $name($($arg_name: $t),*) -> $ret {
             use super::os;
@@ -118,10 +123,12 @@ macro_rules! syscall {
     )
 }
 
+#[cfg_attr(bootstrap, doc = "")]
 #[cfg(any(target_os = "linux", target_os = "android"))]
-macro_rules! syscall {
+pub(crate) macro syscall {
     (fn $name:ident($($arg_name:ident: $t:ty),*) -> $ret:ty) => (
         unsafe fn $name($($arg_name:$t),*) -> $ret {
+            use weak;
             // This looks like a hack, but concat_idents only accepts idents
             // (not paths).
             use libc::*;