Fix for issue #524 (#527)

Check whether Protocol.__doc__ exists before modifying it.
Fixes the crash in typing_extensions when run with -OO flag.

Author: Nickatak

python2/test_typing.py

@@ -2,8 +2,10 @@
 
 import collections
 import contextlib
+import os
 import pickle
 import re
+import subprocess
 import sys
 from unittest import TestCase, main, SkipTest
 from copy import copy, deepcopy
@@ -1963,6 +1965,16 @@ def foo(x):
 
         self.assertIsNone(typing.get_type_hints(foo))
 
+    def test_typing_compiles_with_opt(self):
+        file_path = os.path.join(os.path.dirname(os.path.realpath(__file__)),
+                                 'typing.py')
+        try:
+            subprocess.check_output('python -OO {}'.format(file_path),
+                                    stderr=subprocess.STDOUT,
+                                    shell=True)
+        except subprocess.CalledProcessError:
+            self.fail('Module does not compile with optimize=2 (-OO flag).')
+
 
 if __name__ == '__main__':
     main()

src/test_typing.py

@@ -1,7 +1,9 @@
 import contextlib
 import collections
+import os
 import pickle
 import re
+import subprocess
 import sys
 from unittest import TestCase, main, skipUnless, SkipTest, expectedFailure
 from copy import copy, deepcopy
@@ -2638,6 +2640,16 @@ def test_all(self):
         self.assertIn('SupportsBytes', a)
         self.assertIn('SupportsComplex', a)
 
+    def test_typing_compiles_with_opt(self):
+        file_path = os.path.join(os.path.dirname(os.path.realpath(__file__)),
+                                 'typing.py')
+        try:
+            subprocess.check_output('python -OO {}'.format(file_path),
+                                    stderr=subprocess.STDOUT,
+                                    shell=True)
+        except subprocess.CalledProcessError:
+            self.fail('Module does not compile with optimize=2 (-OO flag).')
+
 
 if __name__ == '__main__':
     main()

typing_extensions/src_py2/test_typing_extensions.py

@@ -4,6 +4,7 @@
 import contextlib
 import collections
 import pickle
+import subprocess
 from unittest import TestCase, main, skipUnless
 
 from typing_extensions import NoReturn, ClassVar
@@ -740,6 +741,16 @@ def test_typing_extensions_defers_when_possible(self):
                     getattr(typing_extensions, item),
                     getattr(typing, item))
 
+    def test_typing_extensions_compiles_with_opt(self):
+        file_path = os.path.join(os.path.dirname(os.path.realpath(__file__)),
+                                 'typing_extensions.py')
+        try:
+            subprocess.check_output('python -OO {}'.format(file_path),
+                                    stderr=subprocess.STDOUT,
+                                    shell=True)
+        except subprocess.CalledProcessError:
+            self.fail('Module does not compile with optimize=2 (-OO flag).')
+
 
 if __name__ == '__main__':
     main()

typing_extensions/src_py3/test_typing_extensions.py

@@ -4,6 +4,7 @@
 import contextlib
 import collections
 import pickle
+import subprocess
 from unittest import TestCase, main, skipUnless
 from typing import TypeVar, Optional
 from typing import T, KT, VT  # Not in __all__.
@@ -1208,6 +1209,7 @@ class E:
 
 
 class AllTests(BaseTestCase):
+
     def test_typing_extensions_includes_standard(self):
         a = typing_extensions.__all__
         self.assertIn('ClassVar', a)
@@ -1244,6 +1246,16 @@ def test_typing_extensions_defers_when_possible(self):
                     getattr(typing_extensions, item),
                     getattr(typing, item))
 
+    def test_typing_extensions_compiles_with_opt(self):
+        file_path = os.path.join(os.path.dirname(os.path.realpath(__file__)),
+                                 'typing_extensions.py')
+        try:
+            subprocess.check_output('python -OO {}'.format(file_path),
+                                    stderr=subprocess.STDOUT,
+                                    shell=True)
+        except subprocess.CalledProcessError:
+            self.fail('Module does not compile with optimize=2 (-OO flag).')
+
 
 if __name__ == '__main__':
    main()

typing_extensions/src_py3/typing_extensions.py

@@ -981,9 +981,9 @@ def __new__(cls, *args, **kwds):
             if OLD_GENERICS:
                 return _generic_new(_next_in_mro(cls), cls, *args, **kwds)
             return _generic_new(cls.__next_in_mro__, cls, *args, **kwds)
-
-    Protocol.__doc__ = Protocol.__doc__.format(bases="Protocol, Generic[T]" if
-                                               OLD_GENERICS else "Protocol[T]")
+    if Protocol.__doc__ is not None:
+        Protocol.__doc__ = Protocol.__doc__.format(bases="Protocol, Generic[T]" if
+                                                   OLD_GENERICS else "Protocol[T]")
 
     def runtime(cls):
         """Mark a protocol class as a runtime protocol, so that it