* Add _PyInitError functions:
* _PyInitError_Ok()
* _PyInitError_Error()
* _PyInitError_NoMemory()
* _PyInitError_Exit()
* _PyInitError_IsError()
* _PyInitError_IsExit()
* _PyInitError_Failed()
* frozenmain.c and _testembed.c now use functions rather than macros.
* Move _Py_INIT_xxx() macros to the internal API.
* Move _PyWstrList_INIT macro to the internal API.
Py_Main() and _Py_RunMain() now return the exitcode rather than
calling Py_Exit(exitcode) when calling PyErr_Print() if the current
exception type is SystemExit.
* Add _Py_HandleSystemExit().
* Add pymain_exit_err_print().
* Add pymain_exit_print().
_PyPreConfig_InitIsolatedConfig() sets configure_locale to 0 to
prevent Python to modify the LC_CTYPE locale. In that case,
coerce_c_locale an coerce_c_locale_warn are set to 0 as well.
Add new functions to get the Python interpreter behavior:
* _PyPreConfig_InitPythonConfig()
* _PyCoreConfig_InitPythonConfig()
Add new functions to get an isolated configuration:
* _PyPreConfig_InitIsolatedConfig()
* _PyCoreConfig_InitIsolatedConfig()
Replace _PyPreConfig_INIT and _PyCoreConfig_INIT with new functions
_PyPreConfig_Init() and _PyCoreConfig_Init().
_PyCoreConfig: set configure_c_stdio and parse_argv to 0 by default
to behave as Python 3.6 in the default configuration.
_PyCoreConfig_Read() no longer sets coerce_c_locale_warn to 1 if it's
equal to 0. coerce_c_locale_warn must now be set to -1 (ex: using
_PyCoreConfig_InitPythonConfig()) to enable C locale coercion
warning.
Add unit tests for _PyCoreConfig_InitPythonConfig()
and _PyCoreConfig_InitIsolatedConfig().
Changes:
* Rename _PyCoreConfig_GetCoreConfig() to _PyPreConfig_GetCoreConfig()
* Fix core_read_precmdline(): handle parse_argv=0
* Fix _Py_PreInitializeFromCoreConfig(): pass coreconfig.argv
to _Py_PreInitializeFromPyArgv(), except if parse_argv=0
* Add PyMemAllocatorName enum
* _PyPreConfig.allocator type becomes PyMemAllocatorName, instead of
char*
* Remove _PyPreConfig_Clear()
* Add _PyMem_GetAllocatorName()
* Rename _PyMem_GetAllocatorsName() to
_PyMem_GetCurrentAllocatorName()
* Remove _PyPreConfig_SetAllocator(): just call
_PyMem_SetupAllocators() directly, we don't have do reallocate the
configuration with the new allocator anymore!
* _PyPreConfig_Write() parameter becomes const, as it should be in
the first place!
Move the check for dead conditionals (if 0) to the peephole optimizer
and make sure that the code block is still compiled to report any
existing syntax errors within.
* Add a private _Py_InitializeMain() function.
* Add again _PyCoreConfig._init_main.
* _Py_InitializeFromConfig() now uses _init_main to decide
if _Py_InitializeMainInterpreter() should be called.
* _PyCoreConfig: rename _frozen to pathconfig_warnings, its value is
now the opposite of Py_FrozenFlag.
* Add an unit test for _init_main=0 and _Py_InitializeMain().
* _PyCoreConfig_Read() doesn't parse nor update argv
if parse_argv is 0.
* Move path configuration fields in _PyCoreConfig.
* Add an unit test for parse_argv=0.
* Remove unused "done": label in _Py_RunMain().
We cannot use "unsigned int" for exitcode on Windows, since
Py_Main() and _Py_RunMain() always return an "int".
Changes:
* _PyPathConfig_ComputeSysPath0() now returns -1 if an exception is
raised.
* pymain_run_python() no longer uses _PyInitError but display the
exception and set exitcode to 1 in case of error.
* Fix _Py_RunMain(): return an exitcode rather than calling
exit() on pymain_run_python() failure.
* _Py_ExitInitError() no longer uses ExitProcess() on Windows, use
exit() on all platforms.
* _Py_ExitInitError() now fails with a fatal error if 'err' is not an
error not an exit.
Remove the PyEval_ReInitThreads() function from the Python C API.
It should not be called explicitly: use PyOS_AfterFork_Child()
instead.
Rename PyEval_ReInitThreads() to _PyEval_ReInitThreads() and add a
'runtime' parameter.
Add "struct _ceval_runtime_state *ceval = &_PyRuntime.ceval;" local
variables to function to better highlight the dependency on the
global variable _PyRuntime and to point directly to _PyRuntime.ceval
field rather than on the larger _PyRuntime.
Changes:
* Add _PyRuntimeState_GetThreadState(runtime) macro.
* Add _PyEval_AddPendingCall(ceval, ...) and
_PyThreadState_Swap(gilstate, ...) functions.
* _PyThreadState_GET() macro now calls
_PyRuntimeState_GetThreadState() using &_PyRuntime.
* Add 'ceval' parameter to COMPUTE_EVAL_BREAKER(),
SIGNAL_PENDING_SIGNALS(), _PyEval_SignalAsyncExc(),
_PyEval_SignalReceived() and _PyEval_FiniThreads() macros and
functions.
* Add 'tstate' parameter to call_function(), do_call_core() and
do_raise().
* Add 'runtime' parameter to _Py_CURRENTLY_FINALIZING(),
_Py_FinishPendingCalls() and _PyThreadState_DeleteExcept()
macros and functions.
* Declare 'runtime', 'tstate', 'ceval' and 'eval_breaker' variables
as constant.
Add new trashcan macros to deal with a double deallocation that could occur when the `tp_dealloc` of a subclass calls the `tp_dealloc` of a base class and that base class uses the trashcan mechanism.
Patch by Jeroen Demeyer.
If a "=" is specified a the end of an f-string expression, the f-string will evaluate to the text of the expression, followed by '=', followed by the repr of the value of the expression.
_PyCoreConfig_SetPyArgv() and _PyCoreConfig_SetWideString() now
pre-initialize Python if needed to ensure that the locale encoding is
properly configured.
* Add _Py_PreInitializeFromPyArgv() internal function.
* Add 'args' parameter to _Py_PreInitializeFromCoreConfig()
_PyCoreConfig: Change filesystem_encoding, filesystem_errors,
stdio_encoding and stdio_errors fields type from char* to wchar_t*.
Changes:
* PyInterpreterState: replace fscodec_initialized (int) with fs_codec
structure.
* Add get_error_handler_wide() and unicode_encode_utf8() helper
functions.
* Add error_handler parameter to unicode_encode_locale()
and unicode_decode_locale().
* Remove _PyCoreConfig_SetString().
* Rename _PyCoreConfig_SetWideString() to _PyCoreConfig_SetString().
* Rename _PyCoreConfig_SetWideStringFromString()
to _PyCoreConfig_DecodeLocale().
Add _Py_FORCE_UTF8_LOCALE and _Py_FORCE_UTF8_FS_ENCODING macros to
avoid factorize "#if defined(__ANDROID__) || defined(__VXWORKS__)"
and "#if defined(__APPLE__)".
Cleanup also config_init_fs_encoding().
* Remove _PyInitError.user_err field and _Py_INIT_USER_ERR() macro:
use _Py_INIT_ERR() instead. _Py_ExitInitError() now longer calls
abort() on error: exit with exit code 1 instead.
* Add _PyInitError._type private field.
* exitcode field type is now unsigned int on Windows.
* Rename prefix field to _func.
* Rename msg field to err_msg.
This commit contains the implementation of PEP570: Python positional-only parameters.
* Update Grammar/Grammar with new typedarglist and varargslist
* Regenerate grammar files
* Update and regenerate AST related files
* Update code object
* Update marshal.c
* Update compiler and symtable
* Regenerate importlib files
* Update callable objects
* Implement positional-only args logic in ceval.c
* Regenerate frozen data
* Update standard library to account for positional-only args
* Add test file for positional-only args
* Update other test files to account for positional-only args
* Add News entry
* Update inspect module and related tests
* Add _PyEval_FiniThreads2(). _PyEval_FiniThreads() now only clears
the pending lock, whereas _PyEval_FiniThreads2() destroys the GIL.
* pymain_free() now calls _PyEval_FiniThreads2().
* Py_FinalizeEx() now calls _PyEval_FiniThreads().
PyEval_AcquireLock() and PyEval_AcquireThread() now
terminate the current thread if called while the interpreter is
finalizing, making them consistent with PyEval_RestoreThread(),
Py_END_ALLOW_THREADS, and PyGILState_Ensure().
Py_FinalizeEx() now clears _PyRuntime.warnings variables and
_PyRuntime.exitfuncs.
Changes:
* Add _PyWarnings_Fini(): called by Py_FinalizeEx()
* call_ll_exitfuncs() now clears _PyRuntime.exitfuncs while iterating
on it (on backward order).
Py_InitializeEx() now uses a runtime variable passed to subfunctions,
rather than working directly on the global variable _PyRuntime.
Add 'runtime' parameter to _PyCoreConfig_Write(), _PySys_Create(),
_PySys_InitMain(), _PyGILState_Init(),
emit_stderr_warning_for_legacy_locale() and other subfunctions.
* Add a 'runtime' variable to Py_FinalizeEx() rather than working
directly on the global variable _PyRuntime
* Add a 'runtime' parameter to _PyGC_Fini(), _PyGILState_Fini()
and call_ll_exitfuncs()
The PyOS_AfterFork_Child() function now pass a 'runtime' parameter to
subfunctions.
* Fix _PyRuntimeState_ReInitThreads(): use the correct memory allocator
* Add runtime parameter to _PyRuntimeState_ReInitThreads(),
_PyGILState_Reinit() and _PyInterpreterState_DeleteExceptMain()
* Move _PyGILState_Reinit() to the internal C API.
* Add 'runtime' parameter to _PyThreadState_Init()
* Add 'gilstate' parameter to _PyGILState_NoteThreadState()
* Move _PyThreadState_Init() and _PyThreadState_DeleteExcept()
to the internal C API.
Change PyAPI_FUNC(type), PyAPI_DATA(type) and PyMODINIT_FUNC macros
of pyport.h when Py_BUILD_CORE_MODULE is defined.
The Py_BUILD_CORE_MODULE define must be now be used to build a C
extension as a dynamic library accessing Python internals: export the
PyInit_xxx() function in DLL exports on Windows.
Changes:
* Py_BUILD_CORE_BUILTIN and Py_BUILD_CORE_MODULE now imply
Py_BUILD_CORE directy in pyport.h.
* ceval.c compilation now fails with an error if Py_BUILD_CORE is not
defined, just to ensure that Python is build with the correct
defines.
* setup.py now compiles _pickle.c with Py_BUILD_CORE_MODULE define.
* setup.py compiles _json.c with Py_BUILD_CORE_MODULE define, rather
than Py_BUILD_CORE_BUILTIN define
* PCbuild/pythoncore.vcxproj: Add Py_BUILD_CORE_BUILTIN define.
Fix Python Initialization code on FreeBSD to detect properly when
stdin file descriptor (fd 0) is invalid.
On FreeBSD, fstat() must be used to check if stdin (fd 0) is valid.
dup(0) doesn't fail if stdin is invalid in some cases.
This is effectively an un-revert of #11617 and #12024 (reverted in #12159). Portions of those were merged in other PRs (with lower risk) and this represents the remainder. Note that I found 3 different bugs in the original PRs and have fixed them here.
Fix time.mktime() error handling on AIX for year before 1970.
Other changes:
* mktime(): rename variable 'buf' to 'tm'.
* _PyTime_localtime():
* Use "localtime" rather than "ctime" in the error message
(specific to AIX).
* Always initialize errno to 0 just in case if localtime_r()
doesn't set errno on error.
* On AIX, avoid abs() which is limited to int type.
* EINVAL constant is now always available.
bpo-36443, bpo-36202: Since Python 3.7.0, calling Py_DecodeLocale()
before Py_Initialize() produces mojibake if the LC_CTYPE locale is
coerced and/or if the UTF-8 Mode is enabled by the user
configuration. This change fix the issue by disabling LC_CTYPE
coercion and UTF-8 Mode by default. They must now be enabled
explicitly (opt-in) using the new _Py_PreInitialize() API with
_PyPreConfig.
When embedding Python, set coerce_c_locale and utf8_mode attributes
of _PyPreConfig to -1 to enable automatically these parameters
depending on the LC_CTYPE locale, environment variables and command
line arguments
Alternative: Setting Py_UTF8Mode to 1 always explicitly enables the
UTF-8 Mode.
Changes:
* _PyPreConfig_INIT now sets coerce_c_locale and utf8_mode to 0 by
default.
* _Py_InitializeFromArgs() and _Py_InitializeFromWideArgs() can now
be called with config=NULL.
* _PyCoreConfig_Write() now updates _PyRuntime.preconfig
* Remove _PyPreCmdline_Copy()
* _PyPreCmdline_Read() now accepts _PyPreConfig and _PyCoreConfig
optional configurations.
* Rename _PyPreConfig_ReadFromArgv() to _PyPreConfig_Read(). Simplify
the code.
* Calling _PyCoreConfig_Read() no longer adds the warning options
twice: don't add a warning option if it's already in the list.
* Rename _PyCoreConfig_ReadFromArgv() to _PyCoreConfig_Read().
* Rename config_from_cmdline() to _PyCoreConfig_ReadFromArgv().
* Add more assertions on _PyCoreConfig in _PyCoreConfig_Read().
* Move some functions.
* Make some config functions private.
* Make _PyPreConfig_GetEnv(), _PyCoreConfig_GetEnv() and
_PyCoreConfig_GetEnvDup() private
* _Py_get_env_flag() first parameter becomes "int use_environment"
* Add _Py_GetConfigsAsDict() function to get all configurations as a
dict.
* dump_config() of _testembed.c now dumps preconfig as a separated
key: call _Py_GetConfigsAsDict().
* Make _PyMainInterpreterConfig_AsDict() private.
* Initialize _PyPreConfig.dev_mode to -1.
* _PyPreConfig_Read(): coreconfig has the priority over preconfig.
* _PyCoreConfig_Read() now calls _PyPreCmdline_Read() internally.
* config_from_cmdline() now pass _PyPreCmdline to config_read().
* Add _PyPreCmdline_Copy().
Prepare code to move some _PyPreConfig parameters into _PyPreCmdline.
Changes:
* _PyCoreConfig_ReadFromArgv(): remove preconfig parameter,
use _PyRuntime.preconfig.
* Add _PyPreCmdline_GetPreConfig() (called by _PyPreConfig_Read()).
* Rename _PyPreCmdline_Init() to _PyPreCmdline_SetArgv()
* Factorize _Py_PreInitializeFromPreConfig() code: add
pyinit_preinit().
* _PyPreConfig_Read() now sets coerce_c_locale to 2 if it must be
coerced.
* Remove _PyCoreConfig_ReadPreConfig().
* _PyCoreConfig_Write() now copies updated preconfig into _PyRuntime.
* Add _PyRuntime.pre_initialized: set to 1 when Python
is pre-initialized
* Add _Py_PreInitialize() and _Py_PreInitializeFromPreConfig().
* _PyCoreConfig_Read() now calls _Py_PreInitialize().
* Move _PyPreConfig_GetGlobalConfig() and
_PyCoreConfig_GetGlobalConfig() calls from main.c to preconfig.c
and coreconfig.c.
Calling _PyRuntime_Initialize() after _PyRuntime_Finalize() now re-initializes
_PyRuntime structure. Previously, _PyRuntime_Initialize() did
nothing in that case.
* _PyPathConfig_ComputeSysPath0() now returns 0 if argv is empty.
* Cleanup also _PyPathConfig_ComputeSysPath0() code: move variables
definitions closer to where they are used.
At Python initialization, the current directory is no longer
prepended to sys.path if it has been removed.
Rename _PyPathConfig_ComputeArgv0() to
_PyPathConfig_ComputeSysPath0() to avoid confusion between argv[0]
and sys.path[0].
Python initialization now fails if decoding pybuilddir.txt
configuration file fails at startup.
_PyPathConfig_Calculate() now reports memory allocation failure and
decoding error on decoding pybuilddir.txt content from
UTF-8/surrogateescape.
The last parameter of _Py_wreadlink(), _Py_wrealpath() and
_Py_wgetcwd() is a length, not a size: number of characters including
the trailing NUL character.
Enhance also documentation of error conditions.
The function has no return value.
Fix the following warning on Windows:
python\ceval.c(180): warning C4098: 'PyEval_InitThreads':
'void' function returning a value
Replace messy _Py_wstrlist_xxx() functions with a new clean
_PyWstrList structure and new _PyWstrList_xxx() functions.
Changes:
* Add _PyCoreConfig.use_module_search_paths to decide if
_PyCoreConfig.module_search_paths should be computed or not, to
support empty search path list.
* _PyWstrList_Clear() sets length to 0 and items to NULL, whereas
_Py_wstrlist_clear() only freed memory.
* _PyWstrList_Append() returns an int, whereas _Py_wstrlist_append()
returned _PyInitError.
* _PyWstrList uses Py_ssize_t for the length, instead of int.
* Replace (int, wchar_t**) with _PyWstrList in:
* _PyPreConfig
* _PyCoreConfig
* _PyPreCmdline
* _PyCmdline
* Replace "int orig_argv; wchar_t **orig_argv;"
with "_PyWstrList orig_argv".
* _PyCmdline and _PyPreCmdline now also copy wchar_argv.
* Rename _PyArgv_Decode() to _PyArgv_AsWstrList().
* PySys_SetArgvEx() now pass the fixed (argc, argv) to
_PyPathConfig_ComputeArgv0() (don't pass negative argc or NULL
argv).
* _PyOS_GetOpt() uses Py_ssize_t
The value is a string for string and byte literals, None otherwise.
It is 'u' for u"..." literals, 'b' for b"..." literals, '' for "..." literals.
The 'r' (raw) prefix is ignored.
Does not apply to f-strings.
This appears sufficient to make mypy capable of using the stdlib ast module instead of typed_ast (assuming a mypy patch I'm working on).
WIP: I need to make the tests pass. @ilevkivskyi @serhiy-storchaka
https://bugs.python.org/issue36280
Fix an unlikely memory leak on conversion from string to float in the
function _Py_dg_strtod() used by float(str), complex(str),
pickle.load(), marshal.load(), etc.
Fix an unlikely memory leak in _Py_dg_strtod() on "undfl:" label:
rewrite memory management in this function to always release all
memory before exiting the function. Initialize variables to NULL, and
set them to NULL after calling Bfree() at the "cont:" label.
Note: Bfree(NULL) is well defined: it does nothing.
d_initial, the first state of a particular DFA in the parser has always been initialized to 0 in the old pgen as well as the new pgen. As this value is not used and the first state of each DFA is assumed to be the first element in the array representing it, remove d_initial from the parser to reduce complexity.
This adds a `feature_version` flag to `ast.parse()` (documented) and `compile()` (hidden) that allow tweaking the parser to support older versions of the grammar. In particular if `feature_version` is 5 or 6, the hacks for the `async` and `await` keyword from PEP 492 are reinstated. (For 7 or higher, these are unconditionally treated as keywords, but they are still special tokens rather than `NAME` tokens that the parser driver recognizes.)
https://bugs.python.org/issue35975
bpo-34247, bpo-36142: The PYTHONMALLOC environment variable has the
priority over PYTHONDEV env var and "-X dev" command line option.
For example, PYTHONMALLOC=malloc PYTHONDEVMODE=1 sets the memory
allocators to "malloc" (and not to "debug").
Add an unit test.
* _PyPreConfig_Read() now sets temporarily LC_CTYPE to the user
preferred locale, as _PyPreConfig_Write() will do permanentely.
* Fix _PyCoreConfig_Clear(): clear run_xxx attributes
* _Py_SetArgcArgv() doesn't have to be exported
* _PyCoreConfig_SetGlobalConfig() no longer applies preconfig
* _PyPreConfig_Write() now reallocates the pre-configuration with the
new memory allocator.
* It is no longer needed to force the "default raw memory allocator"
to clear pre-configuration and core configuration. Simplify the
code.
* _PyPreConfig_Write() now does nothing if called after
Py_Initialize(): no longer check if the allocator is the same.
* Remove _PyMem_GetDebugAllocatorsName(): dev mode sets again
allocator to "debug".
* _PyPreConfig_Write() now sets the memory allocator.
* _PyPreConfig_Write() gets a return type: _PyInitError.
* _Py_InitializeCore() now reads and writes the pre-configuration
(set the memory allocator, configure the locale) before reading and
writing the core configuration.
The development mode now uses the effective name of the debug memory
allocator ("pymalloc_debug" or "malloc_debug"). So the name doesn't
change after setting the memory allocator.
* Move 'allocator' and 'dev_mode' fields from _PyCoreConfig
to _PyPreConfig.
* Fix InitConfigTests of test_embed: dev_mode sets allocator to
"debug", add a new tests for env vars with dev mode enabled.
* Move following fields from _PyCoreConfig to _PyPreConfig:
* coerce_c_locale
* coerce_c_locale_warn
* legacy_windows_stdio
* utf8_mode
* _PyPreConfig_ReadFromArgv() is now responsible to choose the
filesystem encoding
* _PyPreConfig_Write() now sets the LC_CTYPE locale
* Add _PyPreConfig structure
* Move 'ignored' and 'use_environment' fields from _PyCoreConfig
to _PyPreConfig
* Add a new "_PyPreConfig preconfig;" field to _PyCoreConfig
* Revert "bpo-36097: Use only public C-API in the_xxsubinterpreters module (adding as necessary). (#12003)"
This reverts commit bcfa450f21.
* Revert "bpo-33608: Simplify ceval's DISPATCH by hoisting eval_breaker ahead of time. (gh-12062)"
This reverts commit bda918bf65.
* Revert "bpo-33608: Use _Py_AddPendingCall() in _PyCrossInterpreterData_Release(). (gh-12024)"
This reverts commit b05b711a2c.
* Revert "bpo-33608: Factor out a private, per-interpreter _Py_AddPendingCall(). (GH-11617)"
This reverts commit ef4ac967e2.
Use UTF-8 as the system encoding on VxWorks.
The main reason are:
1. The locale is frequently misconfigured.
2. Missing some functions to deal with locale in VxWorks C library.
Pgen is the oldest piece of technology in the CPython repository, building it requires various #if[n]def PGEN hacks in other parts of the code and it also depends more and more on CPython internals. This commit removes the old pgen C code and replaces it for a new version implemented in pure Python. This is a modified and adapted version of lib2to3/pgen2 that can generate grammar files compatibles with the current parser.
This commit also eliminates all the #ifdef and code branches related to pgen, simplifying the code and making it more maintainable. The regen-grammar step now uses $(PYTHON_FOR_REGEN) that can be any version of the interpreter, so the new pgen code maintains compatibility with older versions of the interpreter (this also allows regenerating the grammar with the current CI solution that uses Python3.5). The new pgen Python module also makes use of the Grammar/Tokens file that holds the token specification, so is always kept in sync and avoids having to maintain duplicate token definitions.
* Add _PyCoreConfig_ReadFromArgv() function which parses command line
options: move code from main.c to coreconfig.c.
* Add _PyCoreConfig_Write() to write the new configuration: coerce
the LC_CTYPE locale, set Py_xxx global configuration variables,
etc.
* _PyCoreConfig_ReadFromArgv() now only changes the LC_CTYPE locale
temporarily. _PyCoreConfig_Write() becomes responsible to set the
LC_CTYPE locale.
* Add _Py_SetArgcArgv() and _Py_ClearArgcArgv() functions
* Rename many "pymain_xxx()" functions
* Add "const" to some function parameters
* Reorganize main.c to declare functions in the order in which they
are called.
* Move fields from _PyMain to _PyCoreConfig:
* skip_first_line
* run_command
* run_module
* run_filename
* Replace _PyMain.stdin_is_interactive with a new
stdin_is_interactive(config) function
* Rename _PyMain to _PyArgv. Add "const _PyArgv *args" field
to _PyCmdline.
Add a new _Py_INIT_EXIT() macro to be able to exit Python with an
exitcode using _PyInitError API. Rewrite function calls by
pymain_main() to use _PyInitError.
Changes:
* Remove _PyMain.err and _PyMain.status field
* Add _Py_INIT_EXIT() macro and _PyInitError.exitcode field.
* Rename _Py_FatalInitError() to _Py_ExitInitError().
The whole coreconfig.h header is now excluded from Py_LIMITED_API.
Move functions definitions into a new internal pycore_coreconfig.h
header.
* Move Include/coreconfig.h to Include/cpython/coreconfig.h
* coreconfig.h header is now excluded from Py_LIMITED_API
* Move functions to pycore_coreconfig.h
Ensure that the main interpreter is active (in the main thread) for signal-handling operations. This is increasingly relevant as people use subinterpreters more.
https://bugs.python.org/issue35724
Trying to assign a value to __debug__ using the assignment operator is supposed to fail, but
a missing check for forbidden names when setting the context in the ast was preventing this behaviour.
Explicitly reinitialize this every eval *just in case* someone is
calling into an embedded Python where they don't care about an uncaught
KeyboardInterrupt exception (why didn't they leave
`config.install_signal_handlers` set to `0`?!?) but then later call
`Py_Main()` itself (which *checks* this flag and dies with a signal after
its interpreter exits). We don't want a previous embedded interpreter's
uncaught exception to trigger an unexplained signal exit from a future
`Py_Main()` based one.