Fixed overriding instance and subclass checks for types (PY-10229)

python/src/com/jetbrains/python/codeInsight/override/PyOverrideImplementUtil.java

@@ -220,7 +220,9 @@ public class PyOverrideImplementUtil {
         statementBody.append("(");
         final LanguageLevel langLevel = ((PyFile)pyClass.getContainingFile()).getLanguageLevel();
         if (!langLevel.isPy3K()) {
-          statementBody.append(pyClass.getName()).append(", ").append(PyUtil.getFirstParameterName(baseFunction));
+          final String baseFirstName = !baseParams.isEmpty() ? baseParams.get(0).getName() : null;
+          final String firstName = baseFirstName != null ? baseFirstName : PyNames.CANONICAL_SELF;
+          statementBody.append(pyClass.getName()).append(", ").append(firstName);
         }
         statementBody.append(").").append(baseFunction.getName()).append("(");
         if (parameters.size() > 0) {

python/testData/override/instanceCheck.py

@@ -0,0 +1,2 @@
+class MyType(type):
+    <caret>pass

python/testData/override/instanceCheck_after.py

@@ -0,0 +1,3 @@
+class MyType(type):
+    def __instancecheck__(cls, instance):
+        <selection>return super(MyType, cls).__instancecheck__(instance)</selection>

python/testSrc/com/jetbrains/python/PyOverrideTest.java

@@ -97,4 +97,13 @@ public class PyOverrideTest extends PyTestCase {
   public void testKwargs() {  // PY-7401
     doTest3k();
   }
+
+  // PY-10229
+  public void testInstanceCheck() {
+    myFixture.configureByFile("override/" + getTestName(true) + ".py");
+    final PyClass cls = getTopLevelClass(0);
+    final PyFunction method = cls.findMethodByName("__instancecheck__", true);
+    PyOverrideImplementUtil.overrideMethods(myFixture.getEditor(), cls, Collections.singletonList(new PyMethodMember(method)));
+    myFixture.checkResultByFile("override/" + getTestName(true) + "_after.py", true);
+  }
 }