Auto merge of #107586 - SparrowLii:parallel-query, r=cjgillot

Introduce `DynSend` and `DynSync` auto trait for parallel compiler

part of parallel-rustc #101566

This PR introduces `DynSend / DynSync` trait and `FromDyn / IntoDyn` structure in rustc_data_structure::marker. `FromDyn` can dynamically check data structures for thread safety when switching to parallel environments (such as calling `par_for_each_in`). This happens only when `-Z threads > 1` so it doesn't affect single-threaded mode's compile efficiency.

r? `@cjgillot`

3 files changed, 10 insertions, 4 deletions

diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 8aea2d8aedf..2ecd014acdf 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -496,7 +496,7 @@ pub struct GlobalCtxt<'tcx> {
     ///
     /// FIXME(Centril): consider `dyn LintStoreMarker` once
     /// we can upcast to `Any` for some additional type safety.
-    pub lint_store: Lrc<dyn Any + sync::Sync + sync::Send>,
+    pub lint_store: Lrc<dyn Any + sync::DynSync + sync::DynSend>,
 
     pub dep_graph: DepGraph,
 
@@ -648,7 +648,7 @@ impl<'tcx> TyCtxt<'tcx> {
     /// reference to the context, to allow formatting values that need it.
     pub fn create_global_ctxt(
         s: &'tcx Session,
-        lint_store: Lrc<dyn Any + sync::Send + sync::Sync>,
+        lint_store: Lrc<dyn Any + sync::DynSend + sync::DynSync>,
         arena: &'tcx WorkerLocal<Arena<'tcx>>,
         hir_arena: &'tcx WorkerLocal<hir::Arena<'tcx>>,
         untracked: Untracked,
diff --git a/compiler/rustc_middle/src/ty/context/tls.rs b/compiler/rustc_middle/src/ty/context/tls.rs
index fb0d909307e..bf9806f6406 100644
--- a/compiler/rustc_middle/src/ty/context/tls.rs
+++ b/compiler/rustc_middle/src/ty/context/tls.rs
@@ -94,8 +94,8 @@ where
         f(None)
     } else {
         // We could get an `ImplicitCtxt` pointer from another thread.
-        // Ensure that `ImplicitCtxt` is `Sync`.
-        sync::assert_sync::<ImplicitCtxt<'_, '_>>();
+        // Ensure that `ImplicitCtxt` is `DynSync`.
+        sync::assert_dyn_sync::<ImplicitCtxt<'_, '_>>();
 
         unsafe { f(Some(downcast(context))) }
     }
diff --git a/compiler/rustc_middle/src/ty/list.rs b/compiler/rustc_middle/src/ty/list.rs
index 30f036e471c..71911a5a618 100644
--- a/compiler/rustc_middle/src/ty/list.rs
+++ b/compiler/rustc_middle/src/ty/list.rs
@@ -199,6 +199,12 @@ impl<'a, T: Copy> IntoIterator for &'a List<T> {
 
 unsafe impl<T: Sync> Sync for List<T> {}
 
+// We need this since `List` uses extern type `OpaqueListContents`.
+#[cfg(parallel_compiler)]
+use rustc_data_structures::sync::DynSync;
+#[cfg(parallel_compiler)]
+unsafe impl<T: DynSync> DynSync for List<T> {}
+
 // Safety:
 // Layouts of `Equivalent<T>` and `List<T>` are the same, modulo opaque tail,
 // thus aligns of `Equivalent<T>` and `List<T>` must be the same.