Auto merge of #85953 - inquisitivecrystal:weak-linkat-in-fs-hardlink, r=joshtriplett

Fix linker error

Currently, `fs::hard_link` determines whether platforms have `linkat` based on the OS, and uses `link` if they don't. However, this heuristic does not work well if a platform provides `linkat` on newer versions but not on older ones. On old MacOS, this currently causes a linking error.

This commit fixes `fs::hard_link` by telling it to use `weak!` on macOS. This means that, on  that operating system, we now check for `linkat` at runtime and use `link` if it is not available.

Fixes #80804.

`@rustbot` label T-libs-impl

1 files changed, 4 insertions, 0 deletions

diff --git a/library/std/src/sys/unix/rand.rs b/library/std/src/sys/unix/rand.rs
index 44f9eabc319..32895001a65 100644
--- a/library/std/src/sys/unix/rand.rs
+++ b/library/std/src/sys/unix/rand.rs
@@ -26,6 +26,9 @@ mod imp {
     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
         // disable randomness for consistency. Otherwise, we'll try a raw syscall.
@@ -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 {