From 6f092bcad94d466e4d7aedc42dad4f7c606161d4 Mon Sep 17 00:00:00 2001
From: Taiki Endo <te316e89@gmail.com>
Date: Sat, 2 Dec 2023 21:37:23 +0900
Subject: [PATCH] Remove dependency on scopeguard

---
 crossbeam-epoch/Cargo.toml     |  1 -
 crossbeam-epoch/src/guard.rs   | 21 ++++++++++++---------
 crossbeam-skiplist/Cargo.toml  |  4 ----
 crossbeam-skiplist/src/base.rs | 10 +++++++---
 4 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/crossbeam-epoch/Cargo.toml b/crossbeam-epoch/Cargo.toml
index 630c5e8fa..d959a447c 100644
--- a/crossbeam-epoch/Cargo.toml
+++ b/crossbeam-epoch/Cargo.toml
@@ -39,7 +39,6 @@ autocfg = "1"
 [dependencies]
 cfg-if = "1"
 memoffset = "0.9"
-scopeguard = { version = "1.1", default-features = false }
 
 # Enable the use of loom for concurrency testing.
 #
diff --git a/crossbeam-epoch/src/guard.rs b/crossbeam-epoch/src/guard.rs
index da1c5c01b..5fe33807c 100644
--- a/crossbeam-epoch/src/guard.rs
+++ b/crossbeam-epoch/src/guard.rs
@@ -1,8 +1,6 @@
 use core::fmt;
 use core::mem;
 
-use scopeguard::defer;
-
 use crate::atomic::Shared;
 use crate::collector::Collector;
 use crate::deferred::Deferred;
@@ -366,6 +364,17 @@ impl Guard {
     where
         F: FnOnce() -> R,
     {
+        // Ensure the Guard is re-pinned even if the function panics
+        struct ScopeGuard(*const Local);
+        impl Drop for ScopeGuard {
+            fn drop(&mut self) {
+                if let Some(local) = unsafe { self.0.as_ref() } {
+                    mem::forget(local.pin());
+                    local.release_handle();
+                }
+            }
+        }
+
         if let Some(local) = unsafe { self.local.as_ref() } {
             // We need to acquire a handle here to ensure the Local doesn't
             // disappear from under us.
@@ -373,13 +382,7 @@ impl Guard {
             local.unpin();
         }
 
-        // Ensure the Guard is re-pinned even if the function panics
-        defer! {
-            if let Some(local) = unsafe { self.local.as_ref() } {
-                mem::forget(local.pin());
-                local.release_handle();
-            }
-        }
+        let _guard = ScopeGuard(self.local);
 
         f()
     }
diff --git a/crossbeam-skiplist/Cargo.toml b/crossbeam-skiplist/Cargo.toml
index 1828961d7..cbf524087 100644
--- a/crossbeam-skiplist/Cargo.toml
+++ b/crossbeam-skiplist/Cargo.toml
@@ -41,10 +41,6 @@ version = "0.8.5"
 path = "../crossbeam-utils"
 default-features = false
 
-[dependencies.scopeguard]
-version = "1.1.0"
-default-features = false
-
 [dev-dependencies]
 rand = "0.8"
 
diff --git a/crossbeam-skiplist/src/base.rs b/crossbeam-skiplist/src/base.rs
index cd8488601..f8e26c496 100644
--- a/crossbeam-skiplist/src/base.rs
+++ b/crossbeam-skiplist/src/base.rs
@@ -937,9 +937,13 @@ where
                 // We failed. Let's search for the key and try again.
                 {
                     // Create a guard that destroys the new node in case search panics.
-                    let sg = scopeguard::guard((), |_| {
-                        Node::finalize(node.as_raw());
-                    });
+                    struct ScopeGuard<K, V>(*const Node<K, V>);
+                    impl<K, V> Drop for ScopeGuard<K, V> {
+                        fn drop(&mut self) {
+                            unsafe { Node::finalize(self.0) }
+                        }
+                    }
+                    let sg = ScopeGuard(node.as_raw());
                     search = self.search_position(&n.key, guard);
                     mem::forget(sg);
                 }