bpo-39562: Prevent collision of future and compiler flags (GH-19230)

The constant values of future flags in the __future__ module
is updated in order to prevent collision with compiler flags.
Previously PyCF_ALLOW_TOP_LEVEL_AWAIT was clashing
with CO_FUTURE_DIVISION.
This commit is contained in:
Batuhan Taşkaya 2020-04-22 19:09:03 +03:00 committed by GitHub
parent 9b49893900
commit 4454057269
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6 changed files with 48 additions and 21 deletions

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@ -832,6 +832,10 @@ Changes in the Python API
inherit from it should have this method defined.
(Contributed by Kyle Stanley in :issue:`34037`.)
* The constant values of future flags in the :mod:`__future__` module
is updated in order to prevent collision with compiler flags. Previously
``PyCF_ALLOW_TOP_LEVEL_AWAIT`` was clashing with ``CO_FUTURE_DIVISION``.
(Contributed by Batuhan Taskaya in :issue:`39562`)
CPython bytecode changes
------------------------

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@ -88,19 +88,19 @@ typedef struct {
#define CO_ITERABLE_COROUTINE 0x0100
#define CO_ASYNC_GENERATOR 0x0200
/* These are no longer used. */
#if 0
#define CO_GENERATOR_ALLOWED 0x1000
#endif
#define CO_FUTURE_DIVISION 0x2000
#define CO_FUTURE_ABSOLUTE_IMPORT 0x4000 /* do absolute imports by default */
#define CO_FUTURE_WITH_STATEMENT 0x8000
#define CO_FUTURE_PRINT_FUNCTION 0x10000
#define CO_FUTURE_UNICODE_LITERALS 0x20000
/* bpo-39562: These constant values are changed in Python 3.9
to prevent collision with compiler flags. CO_FUTURE_ and PyCF_
constants must be kept unique. PyCF_ constants can use bits from
0x0100 to 0x10000. CO_FUTURE_ constants use bits starting at 0x20000. */
#define CO_FUTURE_DIVISION 0x20000
#define CO_FUTURE_ABSOLUTE_IMPORT 0x40000 /* do absolute imports by default */
#define CO_FUTURE_WITH_STATEMENT 0x80000
#define CO_FUTURE_PRINT_FUNCTION 0x100000
#define CO_FUTURE_UNICODE_LITERALS 0x200000
#define CO_FUTURE_BARRY_AS_BDFL 0x40000
#define CO_FUTURE_GENERATOR_STOP 0x80000
#define CO_FUTURE_ANNOTATIONS 0x100000
#define CO_FUTURE_BARRY_AS_BDFL 0x400000
#define CO_FUTURE_GENERATOR_STOP 0x800000
#define CO_FUTURE_ANNOTATIONS 0x1000000
/* This value is found in the co_cell2arg array when the associated cell
variable does not correspond to an argument. */

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@ -18,12 +18,18 @@ PyAPI_FUNC(PyCodeObject *) PyNode_Compile(struct _node *, const char *);
CO_FUTURE_UNICODE_LITERALS | CO_FUTURE_BARRY_AS_BDFL | \
CO_FUTURE_GENERATOR_STOP | CO_FUTURE_ANNOTATIONS)
#define PyCF_MASK_OBSOLETE (CO_NESTED)
/* bpo-39562: CO_FUTURE_ and PyCF_ constants must be kept unique.
PyCF_ constants can use bits from 0x0100 to 0x10000.
CO_FUTURE_ constants use bits starting at 0x20000. */
#define PyCF_SOURCE_IS_UTF8 0x0100
#define PyCF_DONT_IMPLY_DEDENT 0x0200
#define PyCF_ONLY_AST 0x0400
#define PyCF_IGNORE_COOKIE 0x0800
#define PyCF_TYPE_COMMENTS 0x1000
#define PyCF_ALLOW_TOP_LEVEL_AWAIT 0x2000
#define PyCF_COMPILE_MASK (PyCF_ONLY_AST | PyCF_ALLOW_TOP_LEVEL_AWAIT | \
PyCF_TYPE_COMMENTS | PyCF_DONT_IMPLY_DEDENT)
#ifndef Py_LIMITED_API
typedef struct {

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@ -68,14 +68,14 @@ __all__ = ["all_feature_names"] + all_feature_names
# this module.
CO_NESTED = 0x0010 # nested_scopes
CO_GENERATOR_ALLOWED = 0 # generators (obsolete, was 0x1000)
CO_FUTURE_DIVISION = 0x2000 # division
CO_FUTURE_ABSOLUTE_IMPORT = 0x4000 # perform absolute imports by default
CO_FUTURE_WITH_STATEMENT = 0x8000 # with statement
CO_FUTURE_PRINT_FUNCTION = 0x10000 # print function
CO_FUTURE_UNICODE_LITERALS = 0x20000 # unicode string literals
CO_FUTURE_BARRY_AS_BDFL = 0x40000
CO_FUTURE_GENERATOR_STOP = 0x80000 # StopIteration becomes RuntimeError in generators
CO_FUTURE_ANNOTATIONS = 0x100000 # annotations become strings at runtime
CO_FUTURE_DIVISION = 0x20000 # division
CO_FUTURE_ABSOLUTE_IMPORT = 0x40000 # perform absolute imports by default
CO_FUTURE_WITH_STATEMENT = 0x80000 # with statement
CO_FUTURE_PRINT_FUNCTION = 0x100000 # print function
CO_FUTURE_UNICODE_LITERALS = 0x200000 # unicode string literals
CO_FUTURE_BARRY_AS_BDFL = 0x400000
CO_FUTURE_GENERATOR_STOP = 0x800000 # StopIteration becomes RuntimeError in generators
CO_FUTURE_ANNOTATIONS = 0x1000000 # annotations become strings at runtime
class _Feature:
def __init__(self, optionalRelease, mandatoryRelease, compiler_flag):

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@ -1,5 +1,7 @@
# Test various flavors of legal and illegal future statements
import __future__
import ast
import unittest
from test import support
from textwrap import dedent
@ -75,6 +77,21 @@ class FutureTest(unittest.TestCase):
from test import badsyntax_future10
self.check_syntax_error(cm.exception, "badsyntax_future10", 3)
def test_ensure_flags_dont_clash(self):
# bpo-39562: test that future flags and compiler flags doesn't clash
# obtain future flags (CO_FUTURE_***) from the __future__ module
flags = {
f"CO_FUTURE_{future.upper()}": getattr(__future__, future).compiler_flag
for future in __future__.all_feature_names
}
# obtain some of the exported compiler flags (PyCF_***) from the ast module
flags |= {
flag: getattr(ast, flag)
for flag in dir(ast) if flag.startswith("PyCF_")
}
self.assertCountEqual(set(flags.values()), flags.values())
def test_parserhack(self):
# test that the parser.c::future_hack function works as expected
# Note: although this test must pass, it's not testing the original

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@ -739,7 +739,7 @@ builtin_compile_impl(PyObject *module, PyObject *source, PyObject *filename,
}
if (flags &
~(PyCF_MASK | PyCF_MASK_OBSOLETE | PyCF_DONT_IMPLY_DEDENT | PyCF_ONLY_AST | PyCF_TYPE_COMMENTS))
~(PyCF_MASK | PyCF_MASK_OBSOLETE | PyCF_COMPILE_MASK))
{
PyErr_SetString(PyExc_ValueError,
"compile(): unrecognised flags");