Auto merge of #136471 - safinaskar:parallel, r=SparrowLii

tree-wide: parallel: Fully removed all `Lrc`, replaced with `Arc`

tree-wide: parallel: Fully removed all `Lrc`, replaced with `Arc`

This is continuation of https://github.com/rust-lang/rust/pull/132282 .

I'm pretty sure I did everything right. In particular, I searched all occurrences of `Lrc` in submodules and made sure that they don't need replacement.

There are other possibilities, through.

We can define `enum Lrc<T> { Rc(Rc<T>), Arc(Arc<T>) }`. Or we can make `Lrc` a union and on every clone we can read from special thread-local variable. Or we can add a generic parameter to `Lrc` and, yes, this parameter will be everywhere across all codebase.

So, if you think we should take some alternative approach, then don't merge this PR. But if it is decided to stick with `Arc`, then, please, merge.

cc "Parallel Rustc Front-end" ( https://github.com/rust-lang/rust/issues/113349 )

r? SparrowLii

`@rustbot` label WG-compiler-parallel

2 files changed, 5 insertions, 6 deletions

diff --git a/compiler/rustc_data_structures/src/owned_slice.rs b/compiler/rustc_data_structures/src/owned_slice.rs
index c8be0ab52e9..17c48aee6fa 100644
--- a/compiler/rustc_data_structures/src/owned_slice.rs
+++ b/compiler/rustc_data_structures/src/owned_slice.rs
@@ -1,15 +1,15 @@
 use std::borrow::Borrow;
 use std::ops::Deref;
+use std::sync::Arc;
 
 // Use our fake Send/Sync traits when on not parallel compiler,
 // so that `OwnedSlice` only implements/requires Send/Sync
 // for parallel compiler builds.
 use crate::sync;
-use crate::sync::Lrc;
 
 /// An owned slice.
 ///
-/// This is similar to `Lrc<[u8]>` but allows slicing and using anything as the
+/// This is similar to `Arc<[u8]>` but allows slicing and using anything as the
 /// backing buffer.
 ///
 /// See [`slice_owned`] for `OwnedSlice` construction and examples.
@@ -34,7 +34,7 @@ pub struct OwnedSlice {
     //       \/
     //      ⊂(´･◡･⊂ )∘˚˳° (I am the phantom remnant of #97770)
     #[expect(dead_code)]
-    owner: Lrc<dyn sync::Send + sync::Sync>,
+    owner: Arc<dyn sync::Send + sync::Sync>,
 }
 
 /// Makes an [`OwnedSlice`] out of an `owner` and a `slicer` function.
@@ -86,7 +86,7 @@ where
     // N.B. the HRTB on the `slicer` is important — without it the caller could provide
     // a short lived slice, unrelated to the owner.
 
-    let owner = Lrc::new(owner);
+    let owner = Arc::new(owner);
     let bytes = slicer(&*owner)?;
 
     Ok(OwnedSlice { bytes, owner })
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 7a9533031f4..bea87a6685d 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -18,7 +18,6 @@
 //!
 //! | Type                    | Serial version      | Parallel version                |
 //! | ----------------------- | ------------------- | ------------------------------- |
-//! | `Lrc<T>`                | `rc::Rc<T>`         | `sync::Arc<T>`                  |
 //! |` Weak<T>`               | `rc::Weak<T>`       | `sync::Weak<T>`                 |
 //! | `LRef<'a, T>` [^2]      | `&'a mut T`         | `&'a T`                         |
 //! |                         |                     |                                 |
@@ -109,7 +108,7 @@ pub use std::marker::{Send, Sync};
 #[cfg(target_has_atomic = "64")]
 pub use std::sync::atomic::AtomicU64;
 pub use std::sync::atomic::{AtomicBool, AtomicU32, AtomicUsize};
-pub use std::sync::{Arc as Lrc, OnceLock, Weak};
+pub use std::sync::{OnceLock, Weak};
 
 pub use mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode};
 pub use parking_lot::{