From d7773f6b1c220d43946bce8010847837ad334b74 Mon Sep 17 00:00:00 2001
From: cyrgani <ansgar.w.zielke@gmail.com>
Date: Tue, 30 Sep 2025 00:09:12 +0200
Subject: [PATCH] explicitly implement `!Send` and `!Sync`

---
 library/proc_macro/src/bridge/client.rs  | 17 ++++++-----------
 library/proc_macro/src/bridge/closure.rs |  4 +---
 library/proc_macro/src/bridge/mod.rs     |  8 +++-----
 library/proc_macro/src/bridge/server.rs  | 14 ++------------
 4 files changed, 12 insertions(+), 31 deletions(-)

diff --git a/library/proc_macro/src/bridge/client.rs b/library/proc_macro/src/bridge/client.rs
index 4e519e56a1ed..92558f2b7d9c 100644
--- a/library/proc_macro/src/bridge/client.rs
+++ b/library/proc_macro/src/bridge/client.rs
@@ -26,18 +26,16 @@ macro_rules! define_client_handles {
         $(
             pub(crate) struct $oty {
                 handle: handle::Handle,
-                // Prevent Send and Sync impls. `!Send`/`!Sync` is the usual
-                // way of doing this, but that requires unstable features.
-                // rust-analyzer uses this code and avoids unstable features.
-                _marker: PhantomData<*mut ()>,
             }
 
+            impl !Send for $oty {}
+            impl !Sync for $oty {}
+
             // Forward `Drop::drop` to the inherent `drop` method.
             impl Drop for $oty {
                 fn drop(&mut self) {
                     $oty {
                         handle: self.handle,
-                        _marker: PhantomData,
                     }.drop();
                 }
             }
@@ -64,7 +62,6 @@ macro_rules! define_client_handles {
                 fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
                     $oty {
                         handle: handle::Handle::decode(r, s),
-                        _marker: PhantomData,
                     }
                 }
             }
@@ -74,12 +71,11 @@ macro_rules! define_client_handles {
             #[derive(Copy, Clone, PartialEq, Eq, Hash)]
             pub(crate) struct $ity {
                 handle: handle::Handle,
-                // Prevent Send and Sync impls. `!Send`/`!Sync` is the usual
-                // way of doing this, but that requires unstable features.
-                // rust-analyzer uses this code and avoids unstable features.
-                _marker: PhantomData<*mut ()>,
             }
 
+            impl !Send for $ity {}
+            impl !Sync for $ity {}
+
             impl<S> Encode<S> for $ity {
                 fn encode(self, w: &mut Writer, s: &mut S) {
                     self.handle.encode(w, s);
@@ -90,7 +86,6 @@ macro_rules! define_client_handles {
                 fn decode(r: &mut Reader<'_>, s: &mut S) -> Self {
                     $ity {
                         handle: handle::Handle::decode(r, s),
-                        _marker: PhantomData,
                     }
                 }
             }
diff --git a/library/proc_macro/src/bridge/closure.rs b/library/proc_macro/src/bridge/closure.rs
index e0e688434dce..e5133907854b 100644
--- a/library/proc_macro/src/bridge/closure.rs
+++ b/library/proc_macro/src/bridge/closure.rs
@@ -6,9 +6,7 @@ use std::marker::PhantomData;
 pub(super) struct Closure<'a, A, R> {
     call: unsafe extern "C" fn(*mut Env, A) -> R,
     env: *mut Env,
-    // Prevent Send and Sync impls. `!Send`/`!Sync` is the usual way of doing
-    // this, but that requires unstable features. rust-analyzer uses this code
-    // and avoids unstable features.
+    // Prevent Send and Sync impls.
     //
     // The `'a` lifetime parameter represents the lifetime of `Env`.
     _marker: PhantomData<*mut &'a mut ()>,
diff --git a/library/proc_macro/src/bridge/mod.rs b/library/proc_macro/src/bridge/mod.rs
index 7fd67ba465ef..1b09deb6bfe6 100644
--- a/library/proc_macro/src/bridge/mod.rs
+++ b/library/proc_macro/src/bridge/mod.rs
@@ -160,13 +160,11 @@ pub struct BridgeConfig<'a> {
 
     /// If 'true', always invoke the default panic hook
     force_show_panics: bool,
-
-    // Prevent Send and Sync impls. `!Send`/`!Sync` is the usual way of doing
-    // this, but that requires unstable features. rust-analyzer uses this code
-    // and avoids unstable features.
-    _marker: marker::PhantomData<*mut ()>,
 }
 
+impl !Send for BridgeConfig<'_> {}
+impl !Sync for BridgeConfig<'_> {}
+
 #[forbid(unsafe_code)]
 #[allow(non_camel_case_types)]
 mod api_tags {
diff --git a/library/proc_macro/src/bridge/server.rs b/library/proc_macro/src/bridge/server.rs
index 724ccbd96c59..0bb30698aa1d 100644
--- a/library/proc_macro/src/bridge/server.rs
+++ b/library/proc_macro/src/bridge/server.rs
@@ -295,12 +295,7 @@ impl ExecutionStrategy for SameThread {
 
         let mut dispatch = |buf| dispatcher.dispatch(buf);
 
-        run_client(BridgeConfig {
-            input,
-            dispatch: (&mut dispatch).into(),
-            force_show_panics,
-            _marker: marker::PhantomData,
-        })
+        run_client(BridgeConfig { input, dispatch: (&mut dispatch).into(), force_show_panics })
     }
 }
 
@@ -331,12 +326,7 @@ where
                 client.recv().expect("server died while client waiting for reply")
             };
 
-            run_client(BridgeConfig {
-                input,
-                dispatch: (&mut dispatch).into(),
-                force_show_panics,
-                _marker: marker::PhantomData,
-            })
+            run_client(BridgeConfig { input, dispatch: (&mut dispatch).into(), force_show_panics })
         });
 
         while let Some(b) = server.recv() {