improve _tlv_exit test

Author: joboet

tests/pass/tls/macos_tlv_atexit.rs

@@ -1,34 +1,40 @@
 //@only-target-darwin
 
-use std::ptr;
 use std::thread;
 
 extern "C" {
     fn _tlv_atexit(dtor: unsafe extern "C" fn(*mut u8), arg: *mut u8);
 }
 
-fn register(dtor: extern "C" fn(*mut u8)) {
-    unsafe {
-        _tlv_atexit(dtor, ptr::null_mut());
+fn register<F>(f: F)
+where
+    F: FnOnce() + 'static,
+{
+    unsafe extern "C" fn run<F>(data: *mut u8)
+    where
+        F: FnOnce() + 'static,
+    {
+        unsafe { (*Box::from_raw(data as *mut F))() }
     }
-}
-
-extern "C" fn register_another(_: *mut u8) {
-    println!("registering another dtor");
-    register(run);
-}
 
-extern "C" fn run(_: *mut u8) {
-    println!("dtor was called");
+    unsafe {
+        _tlv_atexit(run::<F>, Box::into_raw(Box::new(f)) as *mut u8);
+    }
 }
 
 fn main() {
     thread::spawn(|| {
-        register(run);
-        register(run);
+        register(|| println!("dtor 2"));
+        register(|| println!("dtor 1"));
+        println!("exiting thread");
     })
     .join()
     .unwrap();
 
-    register(register_another);
+    println!("exiting main");
+    register(|| println!("dtor 5"));
+    register(|| {
+        println!("registering dtor in dtor 4");
+        register(|| println!("dtor 3"));
+    });
 }

tests/pass/tls/macos_tlv_atexit.stdout

@@ -1,4 +1,7 @@
-dtor was called
-dtor was called
-registering another dtor
-dtor was called
+exiting thread
+dtor 1
+dtor 2
+exiting main
+registering dtor in dtor 4
+dtor 3
+dtor 5