From 631cd5845e8de329d0e227aaa707d7ea228b8f8f Mon Sep 17 00:00:00 2001
From: Daniel Baumann <daniel.baumann@progress-linux.org>
Date: Wed, 17 Apr 2024 14:20:29 +0200
Subject: Merging upstream version 1.70.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
---
 vendor/once_cell/src/lib.rs  |  5 ++++-
 vendor/once_cell/src/race.rs | 47 +++++++++++++++++++++++++++++++++-----------
 2 files changed, 39 insertions(+), 13 deletions(-)

(limited to 'vendor/once_cell/src')

diff --git a/vendor/once_cell/src/lib.rs b/vendor/once_cell/src/lib.rs
index 83149ac4f..c2061f89f 100644
--- a/vendor/once_cell/src/lib.rs
+++ b/vendor/once_cell/src/lib.rs
@@ -454,7 +454,10 @@ pub mod unsync {
         /// Returns `None` if the cell is empty.
         #[inline]
         pub fn get(&self) -> Option<&T> {
-            // Safe due to `inner`'s invariant
+            // Safe due to `inner`'s invariant of being written to at most once.
+            // Had multiple writes to `inner` been allowed, a reference to the
+            // value we return now would become dangling by a write of a
+            // different value later.
             unsafe { &*self.inner.get() }.as_ref()
         }
 
diff --git a/vendor/once_cell/src/race.rs b/vendor/once_cell/src/race.rs
index dff5847c8..ee3d51a58 100644
--- a/vendor/once_cell/src/race.rs
+++ b/vendor/once_cell/src/race.rs
@@ -24,10 +24,11 @@ use atomic_polyfill as atomic;
 #[cfg(not(feature = "critical-section"))]
 use core::sync::atomic;
 
-use atomic::{AtomicUsize, Ordering};
+use atomic::{AtomicPtr, AtomicUsize, Ordering};
 use core::cell::UnsafeCell;
 use core::marker::PhantomData;
 use core::num::NonZeroUsize;
+use core::ptr;
 
 /// A thread-safe cell which can be written to only once.
 #[derive(Default, Debug)]
@@ -176,7 +177,7 @@ impl OnceBool {
 
 /// A thread-safe cell which can be written to only once.
 pub struct OnceRef<'a, T> {
-    inner: OnceNonZeroUsize,
+    inner: AtomicPtr<T>,
     ghost: PhantomData<UnsafeCell<&'a T>>,
 }
 
@@ -198,12 +199,13 @@ impl<'a, T> Default for OnceRef<'a, T> {
 impl<'a, T> OnceRef<'a, T> {
     /// Creates a new empty cell.
     pub const fn new() -> OnceRef<'a, T> {
-        OnceRef { inner: OnceNonZeroUsize::new(), ghost: PhantomData }
+        OnceRef { inner: AtomicPtr::new(ptr::null_mut()), ghost: PhantomData }
     }
 
     /// Gets a reference to the underlying value.
     pub fn get(&self) -> Option<&'a T> {
-        self.inner.get().map(|ptr| unsafe { &*(ptr.get() as *const T) })
+        let ptr = self.inner.load(Ordering::Acquire);
+        unsafe { ptr.as_ref() }
     }
 
     /// Sets the contents of this cell to `value`.
@@ -211,8 +213,13 @@ impl<'a, T> OnceRef<'a, T> {
     /// Returns `Ok(())` if the cell was empty and `Err(value)` if it was
     /// full.
     pub fn set(&self, value: &'a T) -> Result<(), ()> {
-        let ptr = NonZeroUsize::new(value as *const T as usize).unwrap();
-        self.inner.set(ptr)
+        let ptr = value as *const T as *mut T;
+        let exchange =
+            self.inner.compare_exchange(ptr::null_mut(), ptr, Ordering::AcqRel, Ordering::Acquire);
+        match exchange {
+            Ok(_) => Ok(()),
+            Err(_) => Err(()),
+        }
     }
 
     /// Gets the contents of the cell, initializing it with `f` if the cell was
@@ -225,9 +232,11 @@ impl<'a, T> OnceRef<'a, T> {
     where
         F: FnOnce() -> &'a T,
     {
-        let f = || NonZeroUsize::new(f() as *const T as usize).unwrap();
-        let ptr = self.inner.get_or_init(f);
-        unsafe { &*(ptr.get() as *const T) }
+        enum Void {}
+        match self.get_or_try_init(|| Ok::<&'a T, Void>(f())) {
+            Ok(val) => val,
+            Err(void) => match void {},
+        }
     }
 
     /// Gets the contents of the cell, initializing it with `f` if
@@ -241,9 +250,23 @@ impl<'a, T> OnceRef<'a, T> {
     where
         F: FnOnce() -> Result<&'a T, E>,
     {
-        let f = || f().map(|value| NonZeroUsize::new(value as *const T as usize).unwrap());
-        let ptr = self.inner.get_or_try_init(f)?;
-        unsafe { Ok(&*(ptr.get() as *const T)) }
+        let mut ptr = self.inner.load(Ordering::Acquire);
+
+        if ptr.is_null() {
+            // TODO replace with `cast_mut` when MSRV reaches 1.65.0 (also in `set`)
+            ptr = f()? as *const T as *mut T;
+            let exchange = self.inner.compare_exchange(
+                ptr::null_mut(),
+                ptr,
+                Ordering::AcqRel,
+                Ordering::Acquire,
+            );
+            if let Err(old) = exchange {
+                ptr = old;
+            }
+        }
+
+        Ok(unsafe { &*ptr })
     }
 
     /// ```compile_fail
-- 
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