use Option::unwrap_or_else fn to avoid some unsafe blocks

(No is difference expected in terms of instructions executed, assuming unwrap is successful.)

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 - propagate critical-section feature selection into portable-atomic
 - cleaner internal result unwapping (should help keep newer MIRI versions happy)
+- use `Option::unwrap_or_else` fn to avoid some unsafe blocks
+  (No is difference expected in terms of instructions executed, assuming unwrap is successful.)
 
 ## 1.19.0
 

src/imp_std.rs

@@ -68,7 +68,9 @@ impl<T> OnceCell<T> {
         initialize_or_wait(
             &self.queue,
             Some(&mut || {
-                let f = unsafe { f.take().unwrap_unchecked() };
+                let f = f.take().unwrap_or_else(|| {
+                    unreachable!();
+                });
                 match f() {
                     Ok(value) => {
                         unsafe { *slot = Some(value) };

src/lib.rs

@@ -559,7 +559,9 @@ pub mod unsync {
             // checked that slot is currently `None`, so this write
             // maintains the `inner`'s invariant.
             *slot = Some(value);
-            Ok(unsafe { slot.as_ref().unwrap_unchecked() })
+            Ok(slot.as_ref().unwrap_or_else(|| {
+                unreachable!();
+            }))
         }
 
         /// Gets the contents of the cell, initializing it with `f`
@@ -630,7 +632,9 @@ pub mod unsync {
             // `assert`, while keeping `set/get` would be sound, but it seems
             // better to panic, rather than to silently use an old value.
             assert!(self.set(val).is_ok(), "reentrant init");
-            Ok(unsafe { self.get().unwrap_unchecked() })
+            Ok(self.get().unwrap_or_else(|| {
+                unreachable!();
+            }))
         }
 
         /// Takes the value out of this `OnceCell`, moving it back to an uninitialized state.
@@ -1077,7 +1081,11 @@ pub mod sync {
         /// ```
         pub fn try_insert(&self, value: T) -> Result<&T, (&T, T)> {
             let mut value = Some(value);
-            let res = self.get_or_init(|| unsafe { value.take().unwrap_unchecked() });
+            let res = self.get_or_init(|| {
+                value.take().unwrap_or_else(|| {
+                    unreachable!();
+                })
+            });
             match value {
                 None => Ok(res),
                 Some(value) => Err((res, value)),