remove dead code: requires_move_before_drop

src/libstd/sys/redox/fast_thread_local.rs

@@ -105,7 +105,3 @@ pub unsafe extern fn destroy_value<T>(ptr: *mut u8) {
         ptr::drop_in_place((*ptr).inner.get());
     }
 }
-
-pub fn requires_move_before_drop() -> bool {
-    false
-}

src/libstd/sys/unix/fast_thread_local.rs

@@ -82,7 +82,3 @@ pub unsafe fn register_dtor(t: *mut u8, dtor: unsafe extern fn(*mut u8)) {
         }
     }
 }
-
-pub fn requires_move_before_drop() -> bool {
-    false
-}

src/libstd/sys/windows/fast_thread_local.rs

@@ -2,7 +2,3 @@
 #![cfg(target_thread_local)]
 
 pub use crate::sys_common::thread_local::register_dtor_fallback as register_dtor;
-
-pub fn requires_move_before_drop() -> bool {
-    false
-}

src/libstd/thread/local.rs

@@ -344,7 +344,7 @@ pub mod fast {
     use crate::fmt;
     use crate::mem;
     use crate::ptr;
-    use crate::sys::fast_thread_local::{register_dtor, requires_move_before_drop};
+    use crate::sys::fast_thread_local::register_dtor;
 
     pub struct Key<T> {
         inner: UnsafeCell<Option<T>>,
@@ -395,17 +395,8 @@ pub mod fast {
         // destructor as running for this thread so calls to `get` will return
         // `None`.
         (*ptr).dtor_running.set(true);
-
-        // Some implementations may require us to move the value before we drop
-        // it as it could get re-initialized in-place during destruction.
-        //
-        // Hence, we use `ptr::read` on those platforms (to move to a "safe"
-        // location) instead of drop_in_place.
-        if requires_move_before_drop() {
-            ptr::read((*ptr).inner.get());
-        } else {
-            ptr::drop_in_place((*ptr).inner.get());
-        }
+        
+        ptr::drop_in_place((*ptr).inner.get());
     }
 }