clear weakref list when reflected object is destroyed (#1758)

lostmsu · web-flow · commit 50da522c3b90 · 2022-04-09T16:10:34.000+02:00
this was missed when #1267 was superseded
diff --git a/src/embed_tests/TestInstanceWrapping.cs b/src/embed_tests/TestInstanceWrapping.cs
@@ -34,6 +34,16 @@ public void OverloadResolution_UnknownToObject()
             }
         }
 
+        [Test]
+        public void WeakRefIsNone_AfterObjectIsGone()
+        {
+            using var makeref = Py.Import("weakref").GetAttr("ref");
+            var ub = new UriBuilder().ToPython();
+            using var weakref = makeref.Invoke(ub);
+            ub.Dispose();
+            Assert.IsTrue(weakref.Invoke().IsNone());
+        }
+
         class Base {}
         class Derived: Base { }
 
diff --git a/src/runtime/Runtime.Delegates.cs b/src/runtime/Runtime.Delegates.cs
@@ -78,6 +78,7 @@ static Delegates()
             PyObject_RichCompareBool = (delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, int, int>)GetFunctionByName(nameof(PyObject_RichCompareBool), GetUnmanagedDll(_PythonDll));
             PyObject_IsInstance = (delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, int>)GetFunctionByName(nameof(PyObject_IsInstance), GetUnmanagedDll(_PythonDll));
             PyObject_IsSubclass = (delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, int>)GetFunctionByName(nameof(PyObject_IsSubclass), GetUnmanagedDll(_PythonDll));
+            PyObject_ClearWeakRefs = (delegate* unmanaged[Cdecl]<BorrowedReference, void>)GetFunctionByName(nameof(PyObject_ClearWeakRefs), GetUnmanagedDll(_PythonDll));
             PyCallable_Check = (delegate* unmanaged[Cdecl]<BorrowedReference, int>)GetFunctionByName(nameof(PyCallable_Check), GetUnmanagedDll(_PythonDll));
             PyObject_IsTrue = (delegate* unmanaged[Cdecl]<BorrowedReference, int>)GetFunctionByName(nameof(PyObject_IsTrue), GetUnmanagedDll(_PythonDll));
             PyObject_Not = (delegate* unmanaged[Cdecl]<BorrowedReference, int>)GetFunctionByName(nameof(PyObject_Not), GetUnmanagedDll(_PythonDll));
@@ -361,6 +362,7 @@ static Delegates()
         internal static delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, int, int> PyObject_RichCompareBool { get; }
         internal static delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, int> PyObject_IsInstance { get; }
         internal static delegate* unmanaged[Cdecl]<BorrowedReference, BorrowedReference, int> PyObject_IsSubclass { get; }
+        internal static delegate* unmanaged[Cdecl]<BorrowedReference, void> PyObject_ClearWeakRefs { get; }
         internal static delegate* unmanaged[Cdecl]<BorrowedReference, int> PyCallable_Check { get; }
         internal static delegate* unmanaged[Cdecl]<BorrowedReference, int> PyObject_IsTrue { get; }
         internal static delegate* unmanaged[Cdecl]<BorrowedReference, int> PyObject_Not { get; }
diff --git a/src/runtime/Runtime.cs b/src/runtime/Runtime.cs
@@ -993,6 +993,18 @@ internal static int PyObject_Compare(BorrowedReference value1, BorrowedReference
 
         internal static int PyObject_IsSubclass(BorrowedReference ob, BorrowedReference type) => Delegates.PyObject_IsSubclass(ob, type);
 
+        internal static void PyObject_ClearWeakRefs(BorrowedReference ob) => Delegates.PyObject_ClearWeakRefs(ob);
+
+        internal static BorrowedReference PyObject_GetWeakRefList(BorrowedReference ob)
+        {
+            Debug.Assert(ob != null);
+            var type = PyObject_TYPE(ob);
+            int offset = Util.ReadInt32(type, TypeOffset.tp_weaklistoffset);
+            if (offset == 0) return BorrowedReference.Null;
+            Debug.Assert(offset > 0);
+            return Util.ReadRef(ob, offset);
+        }
+
 
         internal static int PyCallable_Check(BorrowedReference o) => Delegates.PyCallable_Check(o);
 
diff --git a/src/runtime/Types/ClassBase.cs b/src/runtime/Types/ClassBase.cs
@@ -346,6 +346,12 @@ public static void tp_dealloc(NewReference lastRef)
 
         public static int tp_clear(BorrowedReference ob)
         {
+            var weakrefs = Runtime.PyObject_GetWeakRefList(ob);
+            if (weakrefs != null)
+            {
+                Runtime.PyObject_ClearWeakRefs(ob);
+            }
+
             if (TryFreeGCHandle(ob))
             {
                 IntPtr addr = ob.DangerousGetAddress();

Original file line number	Diff line number	Diff line change
`@@ -346,6 +346,12 @@ public static void tp_dealloc(NewReference lastRef)`
`346`	`346`
`347`	`347`	`public static int tp_clear(BorrowedReference ob)`
`348`	`348`	`{`
	`349`	`+ var weakrefs = Runtime.PyObject_GetWeakRefList(ob);`
	`350`	`+ if (weakrefs != null)`
	`351`	`+ {`
	`352`	`+ Runtime.PyObject_ClearWeakRefs(ob);`
	`353`	`+ }`
	`354`	`+`
`349`	`355`	`if (TryFreeGCHandle(ob))`
`350`	`356`	`{`
`351`	`357`	`IntPtr addr = ob.DangerousGetAddress();`