WIP: refactor(core): use std instead of once_cell

Currently only possible on Nightly Rust, because `wgpu-core` needs
[`std::sync::OnceLock::get_or_try_init`].

[`std::sync::OnceLock::get_or_try_init`]: https://doc.rust-lang.org/stable/std/sync/struct.OnceLock.html#method.get_or_try_init

Cargo.toml

@@ -110,8 +110,6 @@ nanorand = { version = "0.7", default-features = false, features = ["wyrand"] }
 noise = "0.9"
 nv-flip = "0.1"
 obj = "0.10"
-# NOTE: once_cell/std is *required* for some commonly-used features, selecting this per crate
-once_cell = { version = "1.20.2", default-features = false }
 # Firefox has 3.4.0 vendored, so we allow that version in our dependencies
 ordered-float = { version = ">=3,<=4.6", default-features = false }
 parking_lot = "0.12.1"

wgpu-core/Cargo.toml

@@ -123,7 +123,6 @@ document-features.workspace = true
 hashbrown.workspace = true
 indexmap.workspace = true
 log.workspace = true
-once_cell = { workspace = true, features = ["std"] }
 parking_lot.workspace = true
 profiling = { workspace = true, default-features = false }
 raw-window-handle = { workspace = true, optional = true }

wgpu-core/src/pool.rs

@@ -1,16 +1,15 @@
 use std::{
     hash::Hash,
-    sync::{Arc, Weak},
+    sync::{Arc, OnceLock, Weak},
 };
 
 use hashbrown::{hash_map::Entry, HashMap};
-use once_cell::sync::OnceCell;
 
 use crate::lock::{rank, Mutex};
 use crate::FastHashMap;
 
 type SlotInner<V> = Weak<V>;
-type ResourcePoolSlot<V> = Arc<OnceCell<SlotInner<V>>>;
+type ResourcePoolSlot<V> = Arc<OnceLock<SlotInner<V>>>;
 
 pub struct ResourcePool<K, V> {
     inner: Mutex<FastHashMap<K, ResourcePoolSlot<V>>>,
@@ -52,7 +51,7 @@ impl<K: Clone + Eq + Hash, V> ResourcePool<K, V> {
                 // No entry exists for this resource.
                 //
                 // We know that the resource is not alive, so we can create a new entry.
-                Entry::Vacant(entry) => Arc::clone(entry.insert(Arc::new(OnceCell::new()))),
+                Entry::Vacant(entry) => Arc::clone(entry.insert(Arc::new(OnceLock::new()))),
             };
 
             drop(map_guard);