From 4af2c5e4bd078182ccbc17e8077b5fc585ae853a Mon Sep 17 00:00:00 2001
From: George Miao <gm@miao.dev>
Date: Tue, 7 Apr 2026 19:44:20 -0400
Subject: [PATCH 1/2] feat: loom support

---
 .gitignore |  1 +
 Cargo.toml |  7 +++++++
 src/lib.rs | 49 ++++++++++++++++++++++++++++++++-----------------
 3 files changed, 40 insertions(+), 17 deletions(-)

diff --git a/.gitignore b/.gitignore
index 91143dc..65bf486 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 **/*.rs.bk
 Cargo.lock
 .vscode/
+.zed/
diff --git a/Cargo.toml b/Cargo.toml
index 5b0705c..2120a9a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -21,8 +21,12 @@ current_thread_id = []
 nightly = ["current_thread_id"]
 
 [dependencies]
+cfg-if = "1.0.0"
 futures-core = { version = "0.3", optional = true }
 
+[target.'cfg(loom)'.dependencies]
+loom = "0.7"
+
 [dev-dependencies]
 futures-executor = "0.3"
 futures-util = "0.3"
@@ -31,3 +35,6 @@ futures-util = "0.3"
 all-features = true
 # Needed to add "Available on crate feature `futures` only." messages to docs
 rustdoc-args = ["--cfg", "docsrs"]
+
+[lints.rust]
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
diff --git a/src/lib.rs b/src/lib.rs
index 97eb464..33db01b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -89,33 +89,48 @@
 #[cfg_attr(docsrs, doc(cfg(feature = "futures")))]
 mod futures;
 
-#[cfg(feature = "current_thread_id")]
-use std::thread::current_id;
 use std::{
     fmt,
     mem::{self, ManuallyDrop},
     pin::Pin,
-    thread::{self, ThreadId},
 };
 
-#[cfg(not(feature = "current_thread_id"))]
-mod imp {
-    use std::{
-        cell::Cell,
-        thread::{self, ThreadId},
-    };
-    thread_local! {
-        static THREAD_ID: Cell<ThreadId> = Cell::new(thread::current().id());
-    }
+cfg_if::cfg_if! {
+    if #[cfg(loom)] {
+        use loom::{
+            cell::Cell,
+            thread::{self, ThreadId},
+        };
+
+        loom::thread_local! {
+            static THREAD_ID: Cell<ThreadId> = Cell::new(thread::current().id());
+        }
+
+        /// Get the current mocked [`ThreadId`].
+        pub fn current_id() -> ThreadId {
+            THREAD_ID.with(|id| id.get())
+        }
 
-    pub fn current_id() -> ThreadId {
-        THREAD_ID.get()
+    } else if #[cfg(feature = "current_thread_id")] {
+        use std::thread::{self, current_id, ThreadId};
+
+    } else {
+        use std::{
+            cell::Cell,
+            thread::{self, ThreadId},
+        };
+
+        thread_local! {
+            static THREAD_ID: Cell<ThreadId> = Cell::new(thread::current().id());
+        }
+
+        /// Get the current [`ThreadId`].
+        pub fn current_id() -> ThreadId {
+            THREAD_ID.get()
+        }
     }
 }
 
-#[cfg(not(feature = "current_thread_id"))]
-use imp::current_id;
-
 /// A wrapper which allows you to move around non-[`Send`]-types between
 /// threads, as long as you access the contained value only from within the
 /// original thread and make sure that it is dropped from within the original

From 77facb1252ea7e73cdf1bd1246dbfdf001b466fc Mon Sep 17 00:00:00 2001
From: George Miao <gm@miao.dev>
Date: Tue, 7 Apr 2026 22:18:14 -0400
Subject: [PATCH 2/2] feat: merge loom & other

---
 src/lib.rs | 39 +++++++++++++--------------------------
 1 file changed, 13 insertions(+), 26 deletions(-)

diff --git a/src/lib.rs b/src/lib.rs
index 33db01b..4bbd63e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -82,7 +82,10 @@
 //! [`Stream`]: futures_core::Stream
 // To build docs locally use `RUSTDOCFLAGS="--cfg docsrs" cargo doc --open --all-features`
 #![cfg_attr(docsrs, feature(doc_cfg))]
-#![cfg_attr(feature = "current_thread_id", feature(current_thread_id))]
+#![cfg_attr(
+    all(not(loom), feature = "current_thread_id"),
+    feature(current_thread_id)
+)]
 #![warn(missing_docs)]
 
 #[cfg(feature = "futures")]
@@ -96,38 +99,22 @@ use std::{
 };
 
 cfg_if::cfg_if! {
-    if #[cfg(loom)] {
-        use loom::{
-            cell::Cell,
-            thread::{self, ThreadId},
-        };
-
-        loom::thread_local! {
-            static THREAD_ID: Cell<ThreadId> = Cell::new(thread::current().id());
-        }
-
-        /// Get the current mocked [`ThreadId`].
-        pub fn current_id() -> ThreadId {
-            THREAD_ID.with(|id| id.get())
-        }
-
-    } else if #[cfg(feature = "current_thread_id")] {
-        use std::thread::{self, current_id, ThreadId};
-
-    } else {
-        use std::{
-            cell::Cell,
-            thread::{self, ThreadId},
-        };
+    if #[cfg(any(loom, not(feature = "current_thread_id")))] {
+        #[cfg(loom)]
+        use loom::{thread_local, cell::Cell, thread::{self, ThreadId}};
+        #[cfg(not(loom))]
+        use std::{thread_local, cell::Cell, thread::{self, ThreadId}};
 
         thread_local! {
             static THREAD_ID: Cell<ThreadId> = Cell::new(thread::current().id());
         }
 
         /// Get the current [`ThreadId`].
-        pub fn current_id() -> ThreadId {
-            THREAD_ID.get()
+        pub(crate) fn current_id() -> ThreadId {
+            THREAD_ID.with(|id| id.get())
         }
+    } else {
+        use std::thread::{self, current_id, ThreadId};
     }
 }