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gh-146636: Improve ABI/feature selection, add new header for it (GH-148302)

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Improve ABI/feature selection, add new header for it.

Add a test that Python headers themselves don't use
Py_GIL_DISABLED in abi3t: abi3 and abi3t ought to be the
same except the _Py_OPAQUE_PYOBJECT differences.
This is done using the GCC-only poison pragma.

Co-authored-by: Victor Stinner <vstinner@python.org>
This commit is contained in:
Petr Viktorin 2026-04-23 11:52:13 +02:00 • committed by GitHub
parent 3b9397988d
commit ab41a347eb
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
10 changed files with 148 additions and 82 deletions
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22
Include/Python.h
View file

@ -9,10 +9,11 @@
// is not needed.
// Include Python header files
#include "patchlevel.h"
#include "pyconfig.h"
#include "pymacconfig.h"
// Include Python configuration headers
#include "patchlevel.h" // the Python version
#include "pyconfig.h" // information from configure
#include "pymacconfig.h" // overrides for pyconfig
#include "pyabi.h" // feature/ABI selection
// Include standard header files
@ -46,13 +47,11 @@
# endif
#endif
#if defined(Py_GIL_DISABLED)
# if defined(_MSC_VER)
# include <intrin.h> // __readgsqword()
# endif
# if defined(__MINGW32__)
# include <intrin.h> // __readgsqword()
#if !defined(Py_LIMITED_API)
# if defined(Py_GIL_DISABLED)
# if defined(_MSC_VER) || defined(__MINGW32__)
# include <intrin.h> // __readgsqword()
# endif
# endif
#endif // Py_GIL_DISABLED
@ -67,6 +66,7 @@ __pragma(warning(disable: 4201))
// Include Python header files
#include "pyport.h"
#include "exports.h"
#include "pymacro.h"
#include "pymath.h"
#include "pymem.h"

8
Include/exports.h
View file

@ -36,7 +36,7 @@
#define Py_LOCAL_SYMBOL
#endif
/* module init functions outside the core must be exported */
#if defined(Py_BUILD_CORE)
#if defined(_PyEXPORTS_CORE)
#define _PyINIT_EXPORTED_SYMBOL Py_EXPORTED_SYMBOL
#else
#define _PyINIT_EXPORTED_SYMBOL __declspec(dllexport)
@ -64,13 +64,13 @@
/* only get special linkage if built as shared or platform is Cygwin */
#if defined(Py_ENABLE_SHARED) || defined(__CYGWIN__)
# if defined(HAVE_DECLSPEC_DLL)
# if defined(Py_BUILD_CORE) && !defined(Py_BUILD_CORE_MODULE)
# if defined(_PyEXPORTS_CORE) && !defined(_PyEXPORTS_CORE_MODULE)
/* module init functions inside the core need no external linkage */
/* except for Cygwin to handle embedding */
# if !defined(__CYGWIN__)
# define _PyINIT_FUNC_DECLSPEC
# endif /* __CYGWIN__ */
# else /* Py_BUILD_CORE */
# else /* _PyEXPORTS_CORE */
/* Building an extension module, or an embedded situation */
/* public Python functions and data are imported */
/* Under Cygwin, auto-import functions to prevent compilation */
@ -80,7 +80,7 @@
# define PyAPI_FUNC(RTYPE) Py_IMPORTED_SYMBOL RTYPE
# endif /* !__CYGWIN__ */
# define PyAPI_DATA(RTYPE) extern Py_IMPORTED_SYMBOL RTYPE
# endif /* Py_BUILD_CORE */
# endif /* _PyEXPORTS_CORE */
# endif /* HAVE_DECLSPEC_DLL */
#endif /* Py_ENABLE_SHARED */

28
Include/patchlevel.h
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@ -61,32 +61,4 @@
#define PYTHON_ABI_VERSION 3
#define PYTHON_ABI_STRING "3"
/* Stable ABI for free-threaded builds (introduced in PEP 803)
is enabled by one of:
- Py_TARGET_ABI3T, or
- Py_LIMITED_API and Py_GIL_DISABLED.
"Output" macros to be used internally:
- Py_LIMITED_API (defines the subset of API we expose)
- _Py_OPAQUE_PYOBJECT (additionally hides what's ABI-incompatible between
free-threaded & GIL)
(Don't use Py_TARGET_ABI3T directly: it's currently only used to set these
2 macros. It's also available for users' convenience.)
*/
#if defined(Py_LIMITED_API) && defined(Py_GIL_DISABLED) \
&& !defined(Py_TARGET_ABI3T)
# define Py_TARGET_ABI3T Py_LIMITED_API
#endif
#if defined(Py_TARGET_ABI3T)
# define _Py_OPAQUE_PYOBJECT
# if !defined(Py_LIMITED_API)
# define Py_LIMITED_API Py_TARGET_ABI3T
# elif Py_LIMITED_API > Py_TARGET_ABI3T
// if both are defined, use the *lower* version,
// i.e. maximum compatibility
# undef Py_LIMITED_API
# define Py_LIMITED_API Py_TARGET_ABI3T
# endif
#endif
#endif //_Py_PATCHLEVEL_H

121
Include/pyabi.h Normal file
View file

@ -0,0 +1,121 @@
/* Macros that restrict available definitions and select implementations
* to match an ABI stability promise:
*
* - internal API/ABI (may change at any time) -- Py_BUILD_CORE*
* - general CPython API/ABI (may change in 3.x.0) -- default
* - Stable ABI: abi3, abi3t (long-term stable) -- Py_LIMITED_API,
* Py_TARGET_ABI3T, _Py_OPAQUE_PYOBJECT
* - Free-threading (incompatible with non-free-threading builds)
* -- Py_GIL_DISABLED
*/
#ifndef _Py_PYABI_H
#define _Py_PYABI_H
/* Defines to build Python and its standard library:
*
* - Py_BUILD_CORE: Build Python core. Gives access to Python internals; should
* not be used by third-party modules.
* - Py_BUILD_CORE_BUILTIN: Build a Python stdlib module as a built-in module.
* - Py_BUILD_CORE_MODULE: Build a Python stdlib module as a dynamic library.
*
* Py_BUILD_CORE_BUILTIN and Py_BUILD_CORE_MODULE imply Py_BUILD_CORE.
*
* On Windows, Py_BUILD_CORE_MODULE exports "PyInit_xxx" symbol, whereas
* Py_BUILD_CORE_BUILTIN does not.
*/
#if defined(Py_BUILD_CORE_BUILTIN) && !defined(Py_BUILD_CORE)
# define Py_BUILD_CORE
#endif
#if defined(Py_BUILD_CORE_MODULE) && !defined(Py_BUILD_CORE)
# define Py_BUILD_CORE
#endif
/* Check valid values for target ABI macros.
*/
#if defined(Py_LIMITED_API) && Py_LIMITED_API+0 < 3
// Empty Py_LIMITED_API used to work; redefine to
// Python 3.2 to be explicit.
# undef Py_LIMITED_API
# define Py_LIMITED_API 0x03020000
#endif
#if defined(Py_TARGET_ABI3T) && Py_TARGET_ABI3T+0 < 0x030f0000
# error "Py_TARGET_ABI3T must be 0x030f0000 (3.15) or above"
#endif
/* Stable ABI for free-threaded builds (abi3t, introduced in PEP 803)
* is enabled by one of:
* - Py_TARGET_ABI3T, or
* - Py_LIMITED_API and Py_GIL_DISABLED.
*
* These affect set the following, which Python.h should use internally:
* - Py_LIMITED_API (defines the subset of API we expose)
* - _Py_OPAQUE_PYOBJECT (additionally hides what's ABI-incompatible between
* free-threaded & GIL)
*
* (Don't use Py_TARGET_ABI3T directly. It's currently only used to set these
* 2 macros, and defined for users' convenience.)
*/
#if defined(Py_LIMITED_API) && defined(Py_GIL_DISABLED) \
&& !defined(Py_TARGET_ABI3T)
# define Py_TARGET_ABI3T Py_LIMITED_API
#endif
#if defined(Py_TARGET_ABI3T)
# define _Py_OPAQUE_PYOBJECT
# if !defined(Py_LIMITED_API)
# define Py_LIMITED_API Py_TARGET_ABI3T
# elif Py_LIMITED_API > Py_TARGET_ABI3T
// if both are defined, use the *lower* version,
// i.e. maximum compatibility
# undef Py_LIMITED_API
# define Py_LIMITED_API Py_TARGET_ABI3T
# endif
#else
# ifdef _Py_OPAQUE_PYOBJECT
// _Py_OPAQUE_PYOBJECT is a private macro; do not define it directly.
# error "Define Py_TARGET_ABI3T to target abi3t."
# endif
#endif
#if defined(Py_TARGET_ABI3T)
# if !defined(Py_GIL_DISABLED)
// Define Py_GIL_DISABLED for users' needs. Users check this macro to see
// whether they need extra synchronization.
# define Py_GIL_DISABLED
# endif
# if defined(_Py_IS_TESTCEXT)
// When compiling for abi3t, contents of Python.h should not depend
// on Py_GIL_DISABLED.
// We ask GCC to error if it sees the macro from this point on.
// Since users are free to the macro, and there's no way to undo the
// poisoning at the end of Python.h, we only do this in a test module
// (test_cext).
//
// Clang's poisoning is stricter than GCC's: it looks in `#elif`
// expressions after matching `#if`s. We disable it for now.
// We also provide an undocumented, unsupported opt-out macro to help
// porting to other compilers. Consider reaching out if you use it.
# if defined(__GNUC__) && !defined(__clang__) && !defined(_Py_NO_GCC_POISON)
# undef Py_GIL_DISABLED
# pragma GCC poison Py_GIL_DISABLED
# endif
# endif
#endif
/* The internal C API must not be used with the limited C API: make sure
* that Py_BUILD_CORE* macros are not defined in this case.
* But, keep the "original" values, under different names, for "exports.h"
*/
#ifdef Py_BUILD_CORE
# define _PyEXPORTS_CORE
#endif
#ifdef Py_BUILD_CORE_MODULE
# define _PyEXPORTS_CORE_MODULE
#endif
#ifdef Py_LIMITED_API
# undef Py_BUILD_CORE
# undef Py_BUILD_CORE_BUILTIN
# undef Py_BUILD_CORE_MODULE
#endif
#endif // _Py_PYABI_H

39
Include/pyport.h
View file

@ -58,34 +58,6 @@
#endif
/* Defines to build Python and its standard library:
*
* - Py_BUILD_CORE: Build Python core. Give access to Python internals, but
* should not be used by third-party modules.
* - Py_BUILD_CORE_BUILTIN: Build a Python stdlib module as a built-in module.
* - Py_BUILD_CORE_MODULE: Build a Python stdlib module as a dynamic library.
*
* Py_BUILD_CORE_BUILTIN and Py_BUILD_CORE_MODULE imply Py_BUILD_CORE.
*
* On Windows, Py_BUILD_CORE_MODULE exports "PyInit_xxx" symbol, whereas
* Py_BUILD_CORE_BUILTIN does not.
*/
#if defined(Py_BUILD_CORE_BUILTIN) && !defined(Py_BUILD_CORE)
# define Py_BUILD_CORE
#endif
#if defined(Py_BUILD_CORE_MODULE) && !defined(Py_BUILD_CORE)
# define Py_BUILD_CORE
#endif
#if defined(Py_TARGET_ABI3T)
# if !defined(Py_GIL_DISABLED)
// Define Py_GIL_DISABLED for users' needs. This macro is used to enable
// locking needed in for free-threaded interpreters builds.
# define Py_GIL_DISABLED
# endif
#endif
/**************************************************************************
Symbols and macros to supply platform-independent interfaces to basic
C language & library operations whose spellings vary across platforms.
@ -393,17 +365,6 @@ extern "C" {
# define Py_NO_INLINE
#endif
#include "exports.h"
#ifdef Py_LIMITED_API
// The internal C API must not be used with the limited C API: make sure
// that Py_BUILD_CORE macro is not defined in this case. These 3 macros are
// used by exports.h, so only undefine them afterwards.
# undef Py_BUILD_CORE
# undef Py_BUILD_CORE_BUILTIN
# undef Py_BUILD_CORE_MODULE
#endif
/* limits.h constants that may be missing */
#ifndef INT_MAX

5
Lib/test/test_cext/setup.py
View file

@ -18,6 +18,11 @@
# The purpose of test_cext extension is to check that building a C
# extension using the Python C API does not emit C compiler warnings.
'-Werror',
# Enable extra checks for header files, which:
# - need to be enabled somewhere inside Python headers (rather than
# before including Python.h)
# - should not be checked for user code
'-D_Py_IS_TESTCEXT',
]
# C compiler flags for GCC and clang

1
Makefile.pre.in
View file

@ -1214,6 +1214,7 @@ PYTHON_HEADERS= \
$(srcdir)/Include/osdefs.h \
$(srcdir)/Include/osmodule.h \
$(srcdir)/Include/patchlevel.h \
$(srcdir)/Include/pyabi.h \
$(srcdir)/Include/pyatomic.h \
$(srcdir)/Include/pybuffer.h \
$(srcdir)/Include/pycapsule.h \

2
Misc/NEWS.d/next/C_API/2026-04-09-14-45-44.gh-issue-148267.p84kG_.rst Normal file
View file

@ -0,0 +1,2 @@
Using :c:macro:`Py_LIMITED_API` on a non-Windows free-threaded build no
longer needs an extra :c:macro:`Py_GIL_DISABLED`.

1
PCbuild/pythoncore.vcxproj
View file

@ -359,6 +359,7 @@
<ClInclude Include="..\Include\osmodule.h" />
<ClInclude Include="..\Include\patchlevel.h" />
<ClInclude Include="..\Include\py_curses.h" />
<ClInclude Include="..\Include\pyabi.h" />
<ClInclude Include="..\Include\pyatomic.h" />
<ClInclude Include="..\Include\pybuffer.h" />
<ClInclude Include="..\Include\pycapsule.h" />

3
PCbuild/pythoncore.vcxproj.filters
View file

@ -156,6 +156,9 @@
<ClInclude Include="..\Include\py_curses.h">
<Filter>Include</Filter>
</ClInclude>
<ClInclude Include="..\Include\pyabi.h">
<Filter>Include</Filter>
</ClInclude>
<ClInclude Include="..\Include\pyatomic.h">
<Filter>Include</Filter>
</ClInclude>