Mention about change, describe tests, remove old macro

vstinner · Apr 22, 2020 · Mar 30, 2020 · Mar 30, 2020 · Mar 30, 2020 · Mar 30, 2020
commit 7cd943a7d65e54628fd6898e1b78087d894eb93b
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
@@ -827,6 +827,9 @@ Changes in the Python API
   in the object itself.
   (Contributed by Serhiy Storchaka in :issue:`40257`.)
 
+* The constant values of future flags in the :mod:`future` module
+  is updated in order to prevent collision with compiler flags.
+  (Contributed by Batuhan Taskaya in :issue:`39562`)
 
 CPython bytecode changes
 ------------------------

diff --git a/Include/code.h b/Include/code.h
@@ -89,9 +89,8 @@ typedef struct {
 #define CO_ASYNC_GENERATOR      0x0200
 
 /* These are no longer used. */
-#if 0
-#define CO_GENERATOR_ALLOWED    0x10000
-#endif
+/* These values are changed in 3.9 to prevent collision with
+   compiler flags. See issue 39562 for more details. */
 #define CO_FUTURE_DIVISION      0x20000
 #define CO_FUTURE_ABSOLUTE_IMPORT 0x40000 /* do absolute imports by default */
 #define CO_FUTURE_WITH_STATEMENT  0x80000

diff --git a/Lib/test/test_future.py b/Lib/test/test_future.py
@@ -78,10 +78,13 @@ def test_badfuture10(self):
         self.check_syntax_error(cm.exception, "badsyntax_future10", 3)
 
     def test_ensure_flags_dont_clash(self):
+        # test that future flags and compiler flags doesn't clash
+        # obtain future flags (CO_****) from future module
         flags = [
             getattr(__future__, future).compiler_flag
             for future in __future__.all_feature_names
         ]
+        # obtain some of the exported compiler flags (PyCF_****) from ast
         flags.extend(
             getattr(ast, flag) for flag in dir(ast) if flag.startswith("PyCF_")
         )