make windows compat_fn (crudely) work on Miri

library/std/src/sys/windows/compat.rs

@@ -77,6 +77,10 @@ macro_rules! compat_fn {
  static INIT_TABLE_ENTRY: unsafe extern "C" fn() = init;
 
  unsafe extern "C" fn init() {
+ PTR = get_f();
+ }
+
+ unsafe extern "C" fn get_f() -> Option<F> {
  // There is no locking here. This code is executed before main() is entered, and
  // is guaranteed to be single-threaded.
  //
@@ -91,10 +95,11 @@ macro_rules! compat_fn {
  match $crate::sys::c::GetProcAddress(module_handle, symbol_name as *const i8).addr() {
  0 => {}
  n => {
- PTR = Some(mem::transmute::<usize, F>(n));
+ return Some(mem::transmute::<usize, F>(n));
  }
  }
  }
+ return None;
  }
 
  #[allow(dead_code)]
@@ -105,10 +110,15 @@ macro_rules! compat_fn {
  #[allow(dead_code)]
  pub unsafe fn call($($argname: $argtype),*) -> $rettype {
  if let Some(ptr) = PTR {
- ptr($($argname),*)
- } else {
- $fallback_body
+ return ptr($($argname),*);
+ }
+ if cfg!(miri) {
+ // Miri does not run `init`, so we just call `get_f` each time.
+ if let Some(ptr) = get_f() {
+ return ptr($($argname),*);
+ }
  }
+ $fallback_body
  }
  }