[Mono] Implement eager finalization of WeakReference (#76173)

* [Mono] Implement eager finalization of WeakReference

* Make the finalization really eager

* Move the eager finalization a bit earlier - to sgen_finalize_in_range  (PR suggestion)

Co-authored-by: vsadov <8218165+VSadov@users.noreply.github.com>

2 files changed, 0 insertions, 20 deletions

diff --git a/src/libraries/System.Private.CoreLib/src/System/WeakReference.T.cs b/src/libraries/System.Private.CoreLib/src/System/WeakReference.T.cs
index 648a89def9a..3d48ec61d81 100644
--- a/src/libraries/System.Private.CoreLib/src/System/WeakReference.T.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/WeakReference.T.cs
@@ -130,8 +130,6 @@ namespace System
             }
         }
 
-// eager finalization is NYI on Mono
-#if !MONO
         // Note: While WeakReference<T> is formally a finalizable type, the finalizer does not actually run.
         //       Instead the instances are treated specially in GC when scanning for no longer strongly-reachable
         //       finalizable objects.
@@ -142,21 +140,6 @@ namespace System
         }
 #pragma warning restore CA1821 // Remove empty Finalizers
 
-#else
-        // Free all system resources associated with this reference.
-        ~WeakReference()
-        {
-            IntPtr handle = Handle;
-            if (handle != default(IntPtr))
-            {
-                GCHandle.InternalFree(handle);
-
-                // keep the bit that indicates whether this reference was tracking resurrection
-                _handleAndKind &= TracksResurrectionBit;
-            }
-        }
-#endif
-
 #endif
     }
 }
diff --git a/src/libraries/System.Private.CoreLib/src/System/WeakReference.cs b/src/libraries/System.Private.CoreLib/src/System/WeakReference.cs
index 77c83d8e8d3..2f56806b48c 100644
--- a/src/libraries/System.Private.CoreLib/src/System/WeakReference.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/WeakReference.cs
@@ -150,10 +150,7 @@ namespace System
             // Unlike WeakReference<T> case, the instance could be of a derived type and
             //       in such case it is finalized via a finalizer.
 
-// eager finalization is NYI on Mono
-#if !MONO
             Debug.Assert(this.GetType() != typeof(WeakReference));
-#endif
 
             IntPtr handle = Handle;
             if (handle != default(IntPtr))