Update PyStdlibTypeProvider to return "Any" as list element type if list generic is not specified

python/src/com/jetbrains/python/codeInsight/stdlib/PyStdlibTypeProvider.java

@@ -190,7 +190,7 @@ public class PyStdlibTypeProvider extends PyTypeProviderBase {
                                                         @NotNull Map<PyExpression, PyNamedParameter> parameters,
                                                         @NotNull Map<PyGenericType, PyType> substitutions,
                                                         @NotNull TypeEvalContext context) {
-    if (parameters.size() != 1 || substitutions.size() != 1) {
+    if (parameters.size() != 1 || substitutions.size() > 1) {
       return null;
     }
 
@@ -204,7 +204,8 @@ public class PyStdlibTypeProvider extends PyTypeProviderBase {
     }
 
     if (PyABCUtil.isSubtype(firstArgumentType, PyNames.ABC_INTEGRAL, context)) {
-      return Ref.create(substitutions.values().iterator().next());
+      final PyType result = substitutions.isEmpty() ? null : substitutions.values().iterator().next();
+      return Ref.create(result);
     }
 
     if (PyNames.SLICE.equals(firstArgumentType.getName()) && firstArgumentType.isBuiltin()) {

python/testSrc/com/jetbrains/python/PyTypingTest.java

@@ -691,6 +691,15 @@ public class PyTypingTest extends PyTestCase {
            "    expr = x[y]\n");
   }
 
+  public void testGetListOfListsItemByIntegral() {
+    doTest("Any",
+           "from typing import List\n" +
+           "\n" +
+           "def foo(x: List[List]):\n" +
+           "    sublist = x[0]\n" +
+           "    expr = sublist[0]\n");
+  }
+
   private void doTestNoInjectedText(@NotNull String text) {
     myFixture.configureByText(PythonFileType.INSTANCE, text);
     final InjectedLanguageManager languageManager = InjectedLanguageManager.getInstance(myFixture.getProject());