[GR-23218] Make test_descr pass - few more mro() fixes.

PullRequest: graalpython/1349

Author: tomasstupka

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_descr.txt

@@ -106,6 +106,8 @@
 *graalpython.lib-python.3.test.test_descr.MroTest.test_reent_set_bases_on_base
 *graalpython.lib-python.3.test.test_descr.MroTest.test_reent_set_bases_on_direct_base
 *graalpython.lib-python.3.test.test_descr.MroTest.test_reent_set_bases_tp_base_cycle
+*graalpython.lib-python.3.test.test_descr.MroTest.test_tp_subclasses_cycle_error_return_path
+*graalpython.lib-python.3.test.test_descr.MroTest.test_tp_subclasses_cycle_in_update_slots
 *graalpython.lib-python.3.test.test_descr.OperatorsTest.test_complexes
 *graalpython.lib-python.3.test.test_descr.OperatorsTest.test_dicts
 *graalpython.lib-python.3.test.test_descr.OperatorsTest.test_explicit_reverse_methods

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/objects/type/PythonManagedClass.java

@@ -241,12 +241,7 @@ public void setSuperClass(PythonAbstractClass... newBaseClasses) {
         }
 
         try {
-            for (PythonAbstractClass base : newBaseClasses) {
-                if (base != null) {
-                    GetSubclassesNode.getUncached().execute(base).add(this);
-                }
-            }
-
+            // for what follows see also typeobject.c#type_set_bases()
             this.baseClasses = newBaseClasses;
             this.methodResolutionOrder.setInternalArrayObject(ComputeMroNode.doSlowPath(this));
             this.methodResolutionOrder.lookupChanged();
@@ -258,6 +253,20 @@ public void setSuperClass(PythonAbstractClass... newBaseClasses) {
                     pmc.methodResolutionOrder.lookupChanged();
                 }
             }
+            if (this.baseClasses == newBaseClasses) {
+                // take no action if bases were replaced through reentrance
+                for (PythonAbstractClass base : oldBaseClasses) {
+                    if (base instanceof PythonManagedClass) {
+                        GetSubclassesNode.getUncached().execute(base).remove(this);
+                    }
+                }
+                for (PythonAbstractClass base : newBaseClasses) {
+                    if (base instanceof PythonManagedClass) {
+                        GetSubclassesNode.getUncached().execute(base).add(this);
+                    }
+                }
+            }
+
         } catch (PException pe) {
             // undo
             for (int i = 0; i < newBaseClasses.length; i++) {
@@ -268,8 +277,12 @@ public void setSuperClass(PythonAbstractClass... newBaseClasses) {
                     s.addAll(newBasesSubclasses.get(i));
                 }
             }
-
-            this.baseClasses = oldBaseClasses;
+            if (this.baseClasses == newBaseClasses) {
+                // take no action if bases were replaced through reentrance
+                // revert only if set in this call
+                // e.g. the mro() call might have manipulated __bases__
+                this.baseClasses = oldBaseClasses;
+            }
             this.methodResolutionOrder.setInternalArrayObject(oldMRO);
             this.methodResolutionOrder.lookupChanged();