fix optimisation of isinstance(X, type)

Cython/Compiler/Optimize.py

@@ -2090,7 +2090,12 @@ class OptimizeBuiltinCalls(Visitor.MethodDispatcherTransform):
                     entry = env.lookup(test_type_node.entry.name)
                     if entry and entry.type and entry.type.is_builtin_type:
                         builtin_type = entry.type
-            if builtin_type and builtin_type is not Builtin.type_type:
+            if builtin_type is Builtin.type_type:
+                # all types have type "type", but there's only one 'type'
+                if entry.name != 'type' or not (
+                        entry.scope and entry.scope.is_builtin_scope):
+                    builtin_type = None
+            if builtin_type is not None:
                 type_check_function = entry.type.type_check_function(exact=False)
                 if type_check_function in tests:
                     continue

tests/run/isinstance.pyx

@@ -21,7 +21,18 @@ def test_non_optimised():
     return True
 
 @cython.test_assert_path_exists('//PythonCapiCallNode',
-                                '//PythonCapiCallNode//SimpleCallNode')
+                                '//PythonCapiCallNode//SimpleCallNode',
+                                '//PythonCapiFunctionNode[@cname = "PyType_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PyInt_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PyFloat_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PyBytes_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PyUnicode_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PyTuple_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PyList_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PyDict_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PySet_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PySlice_Check"]',
+                                '//PythonCapiFunctionNode[@cname = "PyComplex_Check"]')
 @cython.test_fail_if_path_exists('//SimpleCallNode//SimpleCallNode',
                                  '//SimpleCallNode//PythonCapiCallNode')
 def test_optimised():
@@ -104,9 +115,9 @@ def test_optimised_tuple():
     >>> test_optimised_tuple()
     True
     """
-    assert isinstance(int(),   (int, long, float, bytes, str, unicode, tuple, list, dict, set, slice, A))
-    assert isinstance(list(),  (int, long, float, bytes, str, unicode, tuple, list, dict, set, slice, A))
-    assert isinstance(A(),  (int, long, float, bytes, str, unicode, tuple, list, dict, set, slice, A))
+    assert isinstance(int(),   (int, long, float, bytes, str, unicode, tuple, list, dict, set, slice, type, A))
+    assert isinstance(list(),  (int, long, float, bytes, str, unicode, tuple, list, dict, set, slice, type, A))
+    assert isinstance(A(),  (int, long, float, bytes, str, unicode, tuple, list, dict, set, slice, type, A))
     return True
 
 def test_custom():