Rollup merge of #142384 - celinval:chores-rayon-mv, r=oli-obk

Bringing `rustc_rayon_core` in tree as `rustc_thread_pool`

This PR moves [`rustc_rayon_core`](https://github.com/rust-lang/rustc-rayon/tree/5fadf44/rayon-core) from commit `5fadf44` as suggested in [this zulip thread](https://rust-lang.zulipchat.com/#narrow/channel/187679-t-compiler.2Fparallel-rustc/topic/Bringing.20.60rustc_rayon_core.60.20in.20tree). I tried to split the work into separate commits so it is easy to review. The first commit is a simple copy and paste from the fork, and subsequent changes were made to use the new crate and to ensure the new crate complies with different format and lint expectations.

**Call-out:** I was also wondering if I need to make any further changes to accommodate licensing requirements.

r? oli-obk

3 files changed, 7 insertions, 9 deletions

diff --git a/compiler/rustc_data_structures/Cargo.toml b/compiler/rustc_data_structures/Cargo.toml
index f6a02011618..17204883fb0 100644
--- a/compiler/rustc_data_structures/Cargo.toml
+++ b/compiler/rustc_data_structures/Cargo.toml
@@ -14,7 +14,6 @@ indexmap = "2.4.0"
 jobserver_crate = { version = "0.1.28", package = "jobserver" }
 measureme = "12.0.1"
 rustc-hash = "2.0.0"
-rustc-rayon-core = { version = "0.5.0" }
 rustc-stable-hash = { version = "0.1.0", features = ["nightly"] }
 rustc_arena = { path = "../rustc_arena" }
 rustc_graphviz = { path = "../rustc_graphviz" }
@@ -22,6 +21,7 @@ rustc_hashes = { path = "../rustc_hashes" }
 rustc_index = { path = "../rustc_index", package = "rustc_index" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
+rustc_thread_pool = { path = "../rustc_thread_pool" }
 smallvec = { version = "1.8.1", features = ["const_generics", "union", "may_dangle"] }
 stacker = "0.1.17"
 tempfile = "3.2"
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index b28c333d860..3881f3c2aa8 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -22,8 +22,6 @@
 //! |                         |                     | `parking_lot::Mutex<T>`         |
 //! | `RwLock<T>`             | `RefCell<T>`        | `parking_lot::RwLock<T>`        |
 //! | `MTLock<T>`        [^1] | `T`                 | `Lock<T>`                       |
-//! |                         |                     |                                 |
-//! | `ParallelIterator`      | `Iterator`          | `rayon::iter::ParallelIterator` |
 //!
 //! [^1]: `MTLock` is similar to `Lock`, but the serial version avoids the cost
 //! of a `RefCell`. This is appropriate when interior mutability is not
diff --git a/compiler/rustc_data_structures/src/sync/parallel.rs b/compiler/rustc_data_structures/src/sync/parallel.rs
index ab65c7f3a6b..ff4b60a1031 100644
--- a/compiler/rustc_data_structures/src/sync/parallel.rs
+++ b/compiler/rustc_data_structures/src/sync/parallel.rs
@@ -96,7 +96,7 @@ macro_rules! parallel {
 pub fn spawn(func: impl FnOnce() + DynSend + 'static) {
     if mode::is_dyn_thread_safe() {
         let func = FromDyn::from(func);
-        rayon_core::spawn(|| {
+        rustc_thread_pool::spawn(|| {
             (func.into_inner())();
         });
     } else {
@@ -107,11 +107,11 @@ pub fn spawn(func: impl FnOnce() + DynSend + 'static) {
 // This function only works when `mode::is_dyn_thread_safe()`.
 pub fn scope<'scope, OP, R>(op: OP) -> R
 where
-    OP: FnOnce(&rayon_core::Scope<'scope>) -> R + DynSend,
+    OP: FnOnce(&rustc_thread_pool::Scope<'scope>) -> R + DynSend,
     R: DynSend,
 {
     let op = FromDyn::from(op);
-    rayon_core::scope(|s| FromDyn::from(op.into_inner()(s))).into_inner()
+    rustc_thread_pool::scope(|s| FromDyn::from(op.into_inner()(s))).into_inner()
 }
 
 #[inline]
@@ -124,7 +124,7 @@ where
         let oper_a = FromDyn::from(oper_a);
         let oper_b = FromDyn::from(oper_b);
         let (a, b) = parallel_guard(|guard| {
-            rayon_core::join(
+            rustc_thread_pool::join(
                 move || guard.run(move || FromDyn::from(oper_a.into_inner()())),
                 move || guard.run(move || FromDyn::from(oper_b.into_inner()())),
             )
@@ -158,7 +158,7 @@ fn par_slice<I: DynSend>(
             let (left, right) = items.split_at_mut(items.len() / 2);
             let mut left = state.for_each.derive(left);
             let mut right = state.for_each.derive(right);
-            rayon_core::join(move || par_rec(*left, state), move || par_rec(*right, state));
+            rustc_thread_pool::join(move || par_rec(*left, state), move || par_rec(*right, state));
         }
     }
 
@@ -241,7 +241,7 @@ pub fn par_map<I: DynSend, T: IntoIterator<Item = I>, R: DynSend, C: FromIterato
 pub fn broadcast<R: DynSend>(op: impl Fn(usize) -> R + DynSync) -> Vec<R> {
     if mode::is_dyn_thread_safe() {
         let op = FromDyn::from(op);
-        let results = rayon_core::broadcast(|context| op.derive(op(context.index())));
+        let results = rustc_thread_pool::broadcast(|context| op.derive(op(context.index())));
         results.into_iter().map(|r| r.into_inner()).collect()
     } else {
         vec![op(0)]