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bpo-32101: Add PYTHONDEVMODE environment variable (python#4624)
* bpo-32101: Add sys.flags.dev_mode flag Rename also the "Developer mode" to the "Development mode". * bpo-32101: Add PYTHONDEVMODE environment variable Mention it in the development chapiter.
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‎Doc/library/development.rst‎

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@@ -24,3 +24,6 @@ The list of modules described in this chapter is:
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unittest.mock-examples.rst
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2to3.rst
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test.rst
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See also the Python development mode: the :option:`-X` ``dev`` option and
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:envvar:`PYTHONDEVMODE` environment variable.

‎Doc/library/sys.rst‎

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@@ -334,6 +334,7 @@ always available.
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:const:`bytes_warning` :option:`-b`
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:const:`quiet` :option:`-q`
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:const:`hash_randomization` :option:`-R`
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:const:`dev_mode` :option:`-X` ``dev``
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============================= =============================
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.. versionchanged:: 3.2
@@ -345,6 +346,9 @@ always available.
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.. versionchanged:: 3.3
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Removed obsolete ``division_warning`` attribute.
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.. versionchanged:: 3.7
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Added ``dev_mode`` attribute for the new :option:`-X` ``dev`` flag.
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.. data:: float_info
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‎Doc/using/cmdline.rst‎

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@@ -411,7 +411,7 @@ Miscellaneous options
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nested imports). Note that its output may be broken in multi-threaded
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application. Typical usage is ``python3 -X importtime -c 'import
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asyncio'``. See also :envvar:`PYTHONPROFILEIMPORTTIME`.
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* ``-X dev``: enable CPython's "developer mode", introducing additional
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* ``-X dev``: enable CPython's "development mode", introducing additional
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runtime checks which are too expensive to be enabled by default. It should
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not be more verbose than the default if the code is correct: new warnings
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are only emitted when an issue is detected. Effect of the developer mode:
@@ -426,6 +426,8 @@ Miscellaneous options
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* Enable the :mod:`faulthandler` module to dump the Python traceback
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on a crash.
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* Enable :ref:`asyncio debug mode <asyncio-debug-mode>`.
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* Set the :attr:`~sys.flags.dev_mode` attribute of :attr:`sys.flags` to
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``True``
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It also allows passing arbitrary values and retrieving them through the
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:data:`sys._xoptions` dictionary.
@@ -796,6 +798,14 @@ conflict.
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.. versionadded:: 3.7
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See :pep:`538` for more details.
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.. envvar:: PYTHONDEVMODE
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If this environment variable is set to a non-empty string, enable the
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CPython "development mode". See the :option:`-X` ``dev`` option.
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.. versionadded:: 3.7
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Debug-mode variables
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~~~~~~~~~~~~~~~~~~~~
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‎Doc/whatsnew/3.7.rst‎

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@@ -185,10 +185,10 @@ resolution on Linux and Windows.
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PEP written and implemented by Victor Stinner
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New Developer Mode: -X dev
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--------------------------
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New Development Mode: -X dev
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----------------------------
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Add a new "developer mode": ``-X dev`` command line option to enable debug
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Add a new "development mode": ``-X dev`` command line option to enable debug
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checks at runtime.
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In short, ``python3 -X dev ...`` behaves as ``PYTHONMALLOC=debug python3 -W
@@ -371,6 +371,11 @@ string
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expression pattern for braced placeholders and non-braced placeholders
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separately. (Contributed by Barry Warsaw in :issue:`1198569`.)
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sys
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---
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Added :attr:`sys.flags.dev_mode` flag for the new development mode.
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time
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----
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‎Lib/asyncio/coroutines.py‎

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@@ -27,11 +27,9 @@ def _is_debug_mode():
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# before you define your coroutines. A downside of using this feature
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# is that tracebacks show entries for the CoroWrapper.__next__ method
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# when _DEBUG is true.
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debug = (not sys.flags.ignore_environment and
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bool(os.environ.get('PYTHONASYNCIODEBUG')))
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if hasattr(sys, '_xoptions') and 'dev' in sys._xoptions:
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debug = True
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return debug
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return (sys.flags.dev_mode
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or (not sys.flags.ignore_environment
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and bool(os.environ.get('PYTHONASYNCIODEBUG'))))
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_DEBUG = _is_debug_mode()

‎Lib/test/test_cmd_line.py‎

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@@ -508,14 +508,18 @@ def test_sys_flags_set(self):
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with self.subTest(envar_value=value):
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assert_python_ok('-c', code, **env_vars)
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def run_xdev(self, *args, check_exitcode=True):
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def run_xdev(self, *args, check_exitcode=True, xdev=True):
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env = dict(os.environ)
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env.pop('PYTHONWARNINGS', None)
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env.pop('PYTHONDEVMODE', None)
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# Force malloc() to disable the debug hooks which are enabled
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# by default for Python compiled in debug mode
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env['PYTHONMALLOC'] = 'malloc'
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args = (sys.executable, '-X', 'dev', *args)
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if xdev:
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args = (sys.executable, '-X', 'dev', *args)
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else:
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args = (sys.executable, *args)
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proc = subprocess.run(args,
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stdout=subprocess.PIPE,
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stderr=subprocess.STDOUT,
@@ -526,6 +530,14 @@ def run_xdev(self, *args, check_exitcode=True):
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return proc.stdout.rstrip()
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def test_xdev(self):
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# sys.flags.dev_mode
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code = "import sys; print(sys.flags.dev_mode)"
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out = self.run_xdev("-c", code, xdev=False)
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self.assertEqual(out, "False")
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out = self.run_xdev("-c", code)
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self.assertEqual(out, "True")
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# Warnings
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code = ("import sys, warnings; "
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"print(' '.join('%s::%s' % (f[0], f[2].__name__) "
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"for f in warnings.filters))")
@@ -555,6 +567,7 @@ def test_xdev(self):
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"default::ResourceWarning "
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"default::Warning")
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# Memory allocator debug hooks
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try:
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import _testcapi
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except ImportError:
@@ -569,6 +582,7 @@ def test_xdev(self):
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alloc_name = "malloc_debug"
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self.assertEqual(out, alloc_name)
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# Faulthandler
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try:
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import faulthandler
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except ImportError:
@@ -581,6 +595,7 @@ def test_xdev(self):
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def check_pythonmalloc(self, env_var, name):
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code = 'import _testcapi; print(_testcapi.pymem_getallocatorsname())'
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env = dict(os.environ)
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env.pop('PYTHONDEVMODE', None)
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if env_var is not None:
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env['PYTHONMALLOC'] = env_var
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else:
@@ -621,6 +636,24 @@ def test_pythonmalloc(self):
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with self.subTest(env_var=env_var, name=name):
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self.check_pythonmalloc(env_var, name)
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def test_pythondevmode_env(self):
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# Test the PYTHONDEVMODE environment variable
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code = "import sys; print(sys.flags.dev_mode)"
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env = dict(os.environ)
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env.pop('PYTHONDEVMODE', None)
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args = (sys.executable, '-c', code)
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proc = subprocess.run(args, stdout=subprocess.PIPE,
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universal_newlines=True, env=env)
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self.assertEqual(proc.stdout.rstrip(), 'False')
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self.assertEqual(proc.returncode, 0, proc)
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env['PYTHONDEVMODE'] = '1'
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proc = subprocess.run(args, stdout=subprocess.PIPE,
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universal_newlines=True, env=env)
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self.assertEqual(proc.stdout.rstrip(), 'True')
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self.assertEqual(proc.returncode, 0, proc)
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class IgnoreEnvironmentTest(unittest.TestCase):
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‎Lib/test/test_sys.py‎

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@@ -526,10 +526,12 @@ def test_sys_flags(self):
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attrs = ("debug",
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"inspect", "interactive", "optimize", "dont_write_bytecode",
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"no_user_site", "no_site", "ignore_environment", "verbose",
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"bytes_warning", "quiet", "hash_randomization", "isolated")
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"bytes_warning", "quiet", "hash_randomization", "isolated",
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"dev_mode")
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for attr in attrs:
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self.assertTrue(hasattr(sys.flags, attr), attr)
532-
self.assertEqual(type(getattr(sys.flags, attr)), int, attr)
533+
attr_type = bool if attr == "dev_mode" else int
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self.assertEqual(type(getattr(sys.flags, attr)), attr_type, attr)
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self.assertTrue(repr(sys.flags))
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self.assertEqual(len(sys.flags), len(attrs))
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‎Misc/NEWS.d/next/Library/2017-11-29-00-42-47.bpo-321010.-axD5l.rst‎

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@@ -0,0 +1 @@
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Add :attr:`sys.flags.dev_mode` flag

‎Modules/main.c‎

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@@ -124,7 +124,8 @@ static const char usage_6[] =
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" hooks.\n"
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"PYTHONCOERCECLOCALE: if this variable is set to 0, it disables the locale\n"
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" coercion behavior. Use PYTHONCOERCECLOCALE=warn to request display of\n"
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" locale coercion and locale compatibility warnings on stderr.\n";
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" locale coercion and locale compatibility warnings on stderr.\n"
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"PYTHONDEVMODE: enable the development mode.\n";
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static void
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pymain_usage(int error, const wchar_t* program)
@@ -1520,7 +1521,9 @@ pymain_parse_envvars(_PyMain *pymain)
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if (pymain_init_tracemalloc(pymain) < 0) {
15211522
return -1;
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}
1523-
if (pymain_get_xoption(pymain, L"dev")) {
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if (pymain_get_xoption(pymain, L"dev" ) ||
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pymain_get_env_var("PYTHONDEVMODE"))
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{
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core_config->dev_mode = 1;
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core_config->faulthandler = 1;
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core_config->allocator = "debug";

‎Python/sysmodule.c‎

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@@ -1814,21 +1814,23 @@ static PyStructSequence_Field flags_fields[] = {
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{"quiet", "-q"},
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{"hash_randomization", "-R"},
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{"isolated", "-I"},
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{"dev_mode", "-X dev"},
18171818
{0}
18181819
};
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18201821
static PyStructSequence_Desc flags_desc = {
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"sys.flags", /* name */
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flags__doc__, /* doc */
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flags_fields, /* fields */
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1825+
14
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};
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18271828
static PyObject*
18281829
make_flags(void)
18291830
{
18301831
int pos = 0;
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PyObject *seq;
1833+
_PyCoreConfig *core_config = &_PyGILState_GetInterpreterStateUnsafe()->core_config;
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seq = PyStructSequence_New(&FlagsType);
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if (seq == NULL)
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SetFlag(Py_HashRandomizationFlag);
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SetFlag(Py_IsolatedFlag);
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#undef SetFlag
1858+
PyStructSequence_SET_ITEM(seq, pos++, PyBool_FromLong(core_config->dev_mode));
18561859

18571860
if (PyErr_Occurred()) {
18581861
Py_DECREF(seq);

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