A number of places in the code base (notably ceval.c and frameobject.c) rely on mapping variable names to indices in the frame "locals plus" array (AKA fast locals), and thus opargs. Currently the compiler indirectly encodes that information on the code object as the tuples co_varnames, co_cellvars, and co_freevars. At runtime the dependent code must calculate the proper mapping from those, which isn't ideal and impacts performance-sensitive sections. This is something we can easily address in the compiler instead.
This change addresses the situation by replacing internal use of co_varnames, etc. with a single combined tuple of names in locals-plus order, along with a minimal array mapping each to its kind (local vs. cell vs. free). These two new PyCodeObject fields, co_fastlocalnames and co_fastllocalkinds, are not exposed to Python code for now, but co_varnames, etc. are still available with the same values as before (though computed lazily).
Aside from the (mild) performance impact, there are a number of other benefits:
* there's now a clear, direct relationship between locals-plus and variables
* code that relies on the locals-plus-to-name mapping is simpler
* marshaled code objects are smaller and serialize/de-serialize faster
Also note that we can take this approach further by expanding the possible values in co_fastlocalkinds to include specific argument types (e.g. positional-only, kwargs). Doing so would allow further speed-ups in _PyEval_MakeFrameVector(), which is where args get unpacked into the locals-plus array. It would also allow us to shrink marshaled code objects even further.
https://bugs.python.org/issue43693
Moreover, Py_FrozenMain() relies on Py_InitializeFromConfig() to
handle the PYTHONUNBUFFERED environment variable and configure C
stdio streams like stdout (make the stream unbuffered).
Deprecate the following functions to configure the Python
initialization:
* PySys_AddWarnOption()
* PySys_AddWarnOptionUnicode()
* PySys_AddXOption()
* PySys_HasWarnOptions()
* Py_SetPath()
* Py_SetProgramName()
* Py_SetPythonHome()
* Py_SetStandardStreamEncoding()
* _Py_SetProgramFullPath()
Use the new PyConfig API of the Python Initialization Configuration
instead (PEP 587).
Add frozen modules to sys.stdlib_module_names. For example, add
"_frozen_importlib" and "_frozen_importlib_external" names.
Add "list_frozen" command to Programs/_testembed.
The path configuration is now computed in the "main" initialization.
The core initialization no longer computes it.
* Add _PyConfig_Read() function to read the configuration without
computing the path configuration.
* pyinit_core() no longer computes the path configuration: it is now
computed by init_interp_main().
* The path configuration output members of PyConfig are now optional:
* executable
* base_executable
* prefix
* base_prefix
* exec_prefix
* base_exec_prefix
* _PySys_UpdateConfig() now skips NULL strings in PyConfig.
* _testembed: Rename test_set_config() to test_init_set_config() for
consistency with other tests.
* Inline _PyInterpreterState_SetConfig(): replace it with
_PyConfig_Copy().
* Add _PyErr_SetFromPyStatus()
* Add _PyInterpreterState_GetConfigCopy()
* Add a new _PyInterpreterState_SetConfig() function.
* Add an unit which gets, modifies, and sets the config.
This commit removes the old parser, the deprecated parser module, the old parser compatibility flags and environment variables and all associated support code and documentation.
Export explicitly the Py_GetArgcArgv() function to the C API and
document the function. Previously, it was exported implicitly which
no longer works since Python is built with -fvisibility=hidden.
* Add PyConfig._orig_argv member.
* Py_InitializeFromConfig() no longer calls _PyConfig_Write() twice.
* PyConfig_Read() no longer initializes Py_GetArgcArgv(): it is now
_PyConfig_Write() responsibility.
* _PyConfig_Write() result type becomes PyStatus instead of void.
* Write an unit test on Py_GetArgcArgv().
An isolated subinterpreter cannot spawn threads, spawn a child
process or call os.fork().
* Add private _Py_NewInterpreter(isolated_subinterpreter) function.
* Add isolated=True keyword-only parameter to
_xxsubinterpreters.create().
* Allow again os.fork() in "non-isolated" subinterpreters.
* Rename PyConfig.use_peg to _use_peg_parser
* Document PyConfig._use_peg_parser and mark it a deprecated
* Mark -X oldparser option and PYTHONOLDPARSER env var as deprecated
in the documentation.
* Add use_old_parser() and skip_if_new_parser() to test.support
* Remove sys.flags.use_peg: use_old_parser() uses
_testinternalcapi.get_configs() instead.
* Enhance test_embed tests
* subprocess._args_from_interpreter_flags() copies -X oldparser
For now, we'll rely on the fact that the config structures aren't covered by the stable ABI.
We may revisit this in the future if we further explore the idea of offering a stable embedding API.
(cherry picked from commit bdace21b76)
Fix warnings options priority: PyConfig.warnoptions has the highest
priority, as stated in the PEP 587.
* Document options order in PyConfig.warnoptions documentation.
* Make PyWideStringList_INIT macro private: replace "Py" prefix
with "_Py".
* test_embed: add test_init_warnoptions().
Add a new struct_size field to PyPreConfig and PyConfig structures to
allow to modify these structures in the future without breaking the
backward compatibility.
* Replace private _config_version field with public struct_size field
in PyPreConfig and PyConfig.
* Public PyPreConfig_InitIsolatedConfig() and
PyPreConfig_InitPythonConfig()
return type becomes PyStatus, instead of void.
* Internal _PyConfig_InitCompatConfig(),
_PyPreConfig_InitCompatConfig(), _PyPreConfig_InitFromConfig(),
_PyPreConfig_InitFromPreConfig() return type becomes PyStatus,
instead of void.
* Remove _Py_CONFIG_VERSION
* Update the Initialization Configuration documentation.
Explicitly preinitializes with a Python preconfiguration to avoid
Py_SetPath() implicit preinitialization with a compat
preconfiguration.
Fix also test_init_setpath() and test_init_setpythonhome() on macOS:
use self.test_exe as the executable (and base_executable), rather
than shutil.which('python3').
* Add test_embed.test_init_setpath_config(): test Py_SetPath()
with PyConfig.
* test_init_setpath() and test_init_setpythonhome() no longer call
Py_SetProgramName(), but use the default program name.
* _PyPathConfig: isolated, site_import and base_executable
fields are now only available on Windows.
* If executable is set explicitly in the configuration, ignore
calculated base_executable: _PyConfig_InitPathConfig() copies
executable to base_executable.
* Complete path config documentation.
PyConfig_Read() is now responsible to handle early calls to
PySys_AddXOption() and PySys_AddWarnOption().
Options added by PySys_AddXOption() are now handled the same way than
PyConfig.xoptions and command line -X options.
For example, PySys_AddXOption(L"faulthandler") enables faulthandler
as expected.
Stop using "static PyConfig", PyConfig must now always use
dynamically allocated strings: use PyConfig_SetString(),
PyConfig_SetArgv() and PyConfig_Clear().
* _PyPreConfig_InitCompatConfig() sets utf8_mode to 0.
* Change Py_UTF8Mode default value to 0.
* Fix _PyPreConfig_Copy(): copy also _config_init attrbibute.
* _PyPreConfig_AsDict() exports _config_init
* Fix _PyPreConfig_GetGlobalConfig(): use Py_UTF8Mode if it's greater
than 0, even if utf8_mode >= 0.
* Add unit tests on environment variables using Python API.
* _PyPreConfig_GetGlobalConfig() and _PyCoreConfig_GetGlobalConfig()
now do nothing if the configuration was not initialized with
_PyPreConfig_InitCompatConfig() and _PyCoreConfig_InitCompatConfig()
* Remove utf8_mode=-2 special case: use utf8_mode=-1 instead.
* Fix _PyPreConfig_InitPythonConfig():
* isolated = 0 instead of -1
* use_environment = 1 instead of -1
* Rename _PyConfig_INIT to _PyConfig_INIT_COMPAT
* Rename _PyPreConfig_Init() to _PyPreConfig_InitCompatConfig()
* Rename _PyCoreConfig_Init() to _PyCoreConfig_InitCompatConfig()
* PyInterpreterState_New() now uses _PyCoreConfig_InitPythonConfig()
as default configuration, but it's very quickly overriden anyway.
* _freeze_importlib.c uses _PyCoreConfig_SetString() to set
program_name.
* Cleanup preconfig_init_utf8_mode(): cmdline is always non-NULL.
* Fix encoding and locale tests in test_embed.InitConfigTests.
* InitConfigTests now only computes EXPECTED_CONFIG once.
* Add tests for PYTHONWARNINGS and PYTHONPATH env vars
* Add _PyPreConfig.parse_argv
* Add _PyCoreConfig._config_init field and _PyCoreConfigInitEnum enum
type
* Initialization functions: reject preconfig=NULL and config=NULL
* Add config parameter to _PyCoreConfig_DecodeLocaleErr(): pass
config->argv to _Py_PreInitializeFromPyArgv(), to parse config
command line arguments in preinitialization.
* Add config parameter to _PyCoreConfig_SetString(). It now
preinitializes Python.
* _PyCoreConfig_SetPyArgv() now also preinitializes Python for wide
argv
* Fix _Py_PreInitializeFromCoreConfig(): don't pass args to
_Py_PreInitializeFromPyArgv() if config.parse_argv=0.
* Use "char * const *" and "wchar_t * const *" types for 'argv'
parameters and _PyArgv.argv.
* Add unit test on preinitialization from argv.
* _PyPreConfig.allocator type becomes int
* Add _PyPreConfig_InitFromPreConfig() and
_PyPreConfig_InitFromCoreConfig() helper functions
_PyPreConfig_InitPythonConfig() and _PyCoreConfig_InitPythonConfig()
no longer inherit their values from global configuration variables.
Changes:
* _PyPreCmdline_Read() now ignores -X dev and PYTHONDEVMODE
if dev_mode is already set.
* Inline _PyPreConfig_INIT macro into _PyPreConfig_Init() function.
* Inline _PyCoreConfig_INIT macro into _PyCoreConfig_Init() function.
* Replace _PyCoreConfig_Init() with _PyCoreConfig_InitPythonConfig()
in most tests of _testembed.c.
* Replace _PyCoreConfig_Init() with _PyCoreConfig_InitIsolatedConfig()
in _freeze_importlib.c.
* Move some initialization functions from the internal
to the private API.
* 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.
_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!
* 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().
Remove UNTESTED_CORE_CONFIG from test_embed.InitConfigTests: all core
config fields are now tested!
Changes:
* Test also dll_path on Windows
* Add run_main_config unit test: test config using _Py_RunMain().
_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 a new _testinternalcapi module to test the internal C API.
Move _Py_GetConfigsAsDict() function to the internal C API:
_testembed now uses _testinternalcapi to access the function.
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.
* 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.
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
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.
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
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().
test_embed.InitConfigTests tests more configuration variables.
Changes:
* InitConfigTests tests more core configuration variables:
* base_exec_prefix
* base_prefix
* exec_prefix
* home
* legacy_windows_fs_encoding
* legacy_windows_stdio
* module_search_path_env
* prefix
* "_testembed init_from_config" tests more variables:
* argv
* warnoptions
* xoptions
* InitConfigTests: add check_global_config(), check_core_config() and
check_main_config() subfunctions to cleanup the code. Move also
constants at the class level (ex: COPY_MAIN_CONFIG).
* Fix _PyCoreConfig_AsDict(): don't set stdio_encoding twice
* Use more macros in _PyCoreConfig_AsDict() and
_PyMainInterpreterConfig_AsDict() to reduce code duplication.
* Other minor cleanups.
* Fix _PyCoreConfig_SetGlobalConfig(): set also Py_FrozenFlag
* Fix _PyCoreConfig_AsDict(): export also xoptions
* Add _Py_GetGlobalVariablesAsDict() and _testcapi.get_global_config()
* test.pythoninfo: dump also global configuration variables
* _testembed now serializes global, core and main configurations
using JSON to reuse _Py_GetGlobalVariablesAsDict(),
_PyCoreConfig_AsDict() and _PyMainInterpreterConfig_AsDict(),
rather than duplicating code.
* test_embed.InitConfigTests now test much more configuration
variables
* Fix _PyMainInterpreterConfig_Copy():
copy 'install_signal_handlers' attribute
* Add _PyMainInterpreterConfig_AsDict()
* Add unit tests on the main interpreter configuration
to test_embed.InitConfigTests
* test.pythoninfo: log also main_config
* And pycore_lifecycle.h and pycore_pathconfig.h headers to
Include/internal/
* Move Py_BUILD_CORE specific code from coreconfig.h and
pylifecycle.h to pycore_pathconfig.h and pycore_lifecycle.h
* Move _Py_wstrlist_XXX() definitions and _PyPathConfig code
from pycore_state.h to pycore_pathconfig.h
* Move "Init" and "Fini" function definitions from pylifecycle.c to
pycore_lifecycle.h.
* Revert "bpo-34589: Add -X coerce_c_locale command line option (GH-9378)"
This reverts commit dbdee0073c.
* Revert "bpo-34589: C locale coercion off by default (GH-9073)"
This reverts commit 7a0791b699.
* Revert "bpo-34589: Make _PyCoreConfig.coerce_c_locale private (GH-9371)"
This reverts commit 188ebfa475.
Py_Initialize() and Py_Main() cannot enable the C locale coercion
(PEP 538) anymore: it is always disabled. It can now only be enabled
by the Python program ("python3).
test_embed: get_filesystem_encoding() doesn't have to set PYTHONUTF8
nor PYTHONCOERCECLOCALE, these variables are already set in the
parent.
_PyCoreConfig:
* Rename coerce_c_locale to _coerce_c_locale
* Rename coerce_c_locale_warn to _coerce_c_locale_warn
These fields are now private (name prefixed by "_").
Add support for the "surrogatepass" error handler in
PyUnicode_DecodeFSDefault() and PyUnicode_EncodeFSDefault()
for the UTF-8 encoding.
Changes:
* _Py_DecodeUTF8Ex() and _Py_EncodeUTF8Ex() now support the
surrogatepass error handler (_Py_ERROR_SURROGATEPASS).
* _Py_DecodeLocaleEx() and _Py_EncodeLocaleEx() now use
the _Py_error_handler enum instead of "int surrogateescape" to pass
the error handler. These functions now return -3 if the error
handler is unknown.
* Add unit tests on _Py_DecodeLocaleEx() and _Py_EncodeLocaleEx()
in test_codecs.
* Rename get_error_handler() to _Py_GetErrorHandler() and expose it
as a private function.
* _freeze_importlib doesn't need config.filesystem_errors="strict"
workaround anymore.
_PyCoreConfig_Read() is now responsible to choose the filesystem
encoding and error handler. Using Py_Main(), the encoding is now
chosen even before calling Py_Initialize().
_PyCoreConfig.filesystem_encoding is now the reference, instead of
Py_FileSystemDefaultEncoding, for the Python filesystem encoding.
Changes:
* Add filesystem_encoding and filesystem_errors to _PyCoreConfig
* _PyCoreConfig_Read() now reads the locale encoding for the file
system encoding.
* PyUnicode_EncodeFSDefault() and PyUnicode_DecodeFSDefaultAndSize()
now use the interpreter configuration rather than
Py_FileSystemDefaultEncoding and Py_FileSystemDefaultEncodeErrors
global configuration variables.
* Add _Py_SetFileSystemEncoding() and _Py_ClearFileSystemEncoding()
private functions to only modify Py_FileSystemDefaultEncoding and
Py_FileSystemDefaultEncodeErrors in coreconfig.c.
* _Py_CoerceLegacyLocale() now takes an int rather than
_PyCoreConfig for the warning.
Python now gets the locale encoding with C code to initialize the encoding
of standard streams like sys.stdout. Moreover, the encoding is now
initialized to the Python codec name to get a normalized encoding name and
to ensure that the codec is loaded. The change avoids importing
_bootlocale and _locale modules at startup by default.
When the PYTHONIOENCODING environment variable only contains an encoding,
the error handler is now is now set explicitly to "strict".
Rename also get_default_standard_stream_error_handler() to
get_stdio_errors().
Reduce the buffer to format the "cpXXX" string (Windows locale encoding).
bpo-31650, bpo-34170: Replace _Py_CheckHashBasedPycsMode with
_PyCoreConfig._check_hash_pycs_mode. Modify PyInit__imp() and
zipimport to get the parameter from the current interpreter core
configuration.
Remove Include/internal/import.h file.
* Config: Rename ignore_environment field to use_environment.
* _PyCoreConfig_Read(): if isolated is set, use_environment and
site_import are now always set to 0.
* Inline pymain_free_raw() into pymain_free()
* Move config_init_warnoptions() call into pymain_read_conf_impl()
* _PyCoreConfig_Read(): don't replace values if they are already set:
faulthandler, pycache_prefix, home.
* If _Py_InitializeCore() is called twice, the second call now copies
and apply (partially) the new configuration.
* Rename _Py_CommandLineDetails to _PyCmdline
* Move more code into pymain_init(). The core configuration created
by Py_Main() is new destroyed before running Python to reduce the
memory footprint.
* _Py_InitializeCore() now returns the created interpreter.
_Py_InitializeMainInterpreter() now expects an interpreter.
* Remove _Py_InitializeEx_Private(): _freeze_importlib now uses
_Py_InitializeFromConfig()
* _PyCoreConfig_InitPathConfig() now only computes the path
configuration if needed.
Py_Main() can again be called after Py_Initialize(), as in Python
3.6. The new configuration is ignored, except of
_PyMainInterpreterConfig.argv which is used to update sys.argv.
Eric Snow
Victor Stinner
Konge
Pablo Galindo
Sandro Mani
Victor Stinner
Steve Dower
Steve Dower
Zackery Spytz
Victor Stinner
Serhiy Storchaka
Nick Coghlan