added test and fixes

Author: asmyasnikov

internal/xruntime/cleanup.go

@@ -5,7 +5,7 @@ package xruntime
 import "runtime"
 
 func AddCleanup[T, S any](ptr *T, cleanup func(S), arg S) {
-	runtime.SetFinalizer(ptr, func() {
+	runtime.SetFinalizer(ptr, func(ptr *T) {
 		cleanup(arg)
 	})
 }

internal/xruntime/cleanup_test.go

@@ -0,0 +1,27 @@
+package xruntime
+
+import (
+	"runtime"
+	"testing"
+	"time"
+)
+
+func TestAddCleanup(t *testing.T) {
+	cleanupCalled := make(chan struct{})
+	func() {
+		v := &struct {
+			a int64
+			b string
+			c bool
+		}{}
+		AddCleanup(v, func(cleanupCalled chan struct{}) {
+			close(cleanupCalled)
+		}, cleanupCalled)
+	}()
+	runtime.GC()
+	select {
+	case <-cleanupCalled:
+	case <-time.After(time.Second):
+		t.Fail()
+	}
+}