https://github.com/python/cpython/commit/c3487c941dfa252bde7e69f9d953d4ca9a56408d
commit: c3487c941dfa252bde7e69f9d953d4ca9a56408d
branch: main
author: Jean-Christophe Fillion-Robin <jchris.filli...@kitware.com>
committer: zooba <steve.do...@microsoft.com>
date: 2025-03-10T17:40:17Z
summary:
gh-82909: Update PC/pyconfig.h to allow disabling pragma based auto-linking
(GH-19740)
Define Py_NO_LINK_LIB to build extension disabling pragma based auto-linking.
This is relevant when using build-system generator (e.g CMake) where the
linking is explicitly handled
files:
A Misc/NEWS.d/next/Build/2023-04-02-14-20-29.gh-issue-82909.LGcZJy.rst
M Doc/extending/windows.rst
M Doc/whatsnew/3.14.rst
M PC/pyconfig.h.in
diff --git a/Doc/extending/windows.rst b/Doc/extending/windows.rst
index e366d6cb9f79e3..56aa44e4e58c83 100644
--- a/Doc/extending/windows.rst
+++ b/Doc/extending/windows.rst
@@ -96,6 +96,13 @@ gives you access to spam's names, but does not create a
separate copy. On Unix,
linking with a library is more like ``from spam import *``; it does create a
separate copy.
+.. c:macro:: Py_NO_LINK_LIB
+
+ Turn off the implicit, ``#pragma``-based linkage with the Python
+ library, performed inside CPython header files.
+
+ .. versionadded:: 3.14
+
.. _win-dlls:
@@ -108,21 +115,46 @@ Using DLLs in Practice
Windows Python is built in Microsoft Visual C++; using other compilers may or
may not work. The rest of this section is MSVC++ specific.
-When creating DLLs in Windows, you must pass :file:`pythonXY.lib` to the
linker.
-To build two DLLs, spam and ni (which uses C functions found in spam), you
could
-use these commands::
+When creating DLLs in Windows, you can use the CPython library in two ways:
+
+1. By default, inclusion of :file:`PC/pyconfig.h` directly or via
+ :file:`Python.h` triggers an implicit, configure-aware link with the
+ library. The header file chooses :file:`pythonXY_d.lib` for Debug,
+ :file:`pythonXY.lib` for Release, and :file:`pythonX.lib` for Release with
+ the `Limited API <stable-application-binary-interface>`_ enabled.
+
+ To build two DLLs, spam and ni (which uses C functions found in spam), you
+ could use these commands::
+
+ cl /LD /I/python/include spam.c
+ cl /LD /I/python/include ni.c spam.lib
+
+ The first command created three files: :file:`spam.obj`, :file:`spam.dll`
+ and :file:`spam.lib`. :file:`Spam.dll` does not contain any Python
+ functions (such as :c:func:`PyArg_ParseTuple`), but it does know how to find
+ the Python code thanks to the implicitly linked :file:`pythonXY.lib`.
+
+ The second command created :file:`ni.dll` (and :file:`.obj` and
+ :file:`.lib`), which knows how to find the necessary functions from spam,
+ and also from the Python executable.
+
+2. Manually by defining :c:macro:`Py_NO_LINK_LIB` macro before including
+ :file:`Python.h`. You must pass :file:`pythonXY.lib` to the linker.
+
+ To build two DLLs, spam and ni (which uses C functions found in spam), you
+ could use these commands::
- cl /LD /I/python/include spam.c ../libs/pythonXY.lib
- cl /LD /I/python/include ni.c spam.lib ../libs/pythonXY.lib
+ cl /LD /DPy_NO_LINK_LIB /I/python/include spam.c ../libs/pythonXY.lib
+ cl /LD /DPy_NO_LINK_LIB /I/python/include ni.c spam.lib
../libs/pythonXY.lib
-The first command created three files: :file:`spam.obj`, :file:`spam.dll` and
-:file:`spam.lib`. :file:`Spam.dll` does not contain any Python functions (such
-as :c:func:`PyArg_ParseTuple`), but it does know how to find the Python code
-thanks to :file:`pythonXY.lib`.
+ The first command created three files: :file:`spam.obj`, :file:`spam.dll`
+ and :file:`spam.lib`. :file:`Spam.dll` does not contain any Python
+ functions (such as :c:func:`PyArg_ParseTuple`), but it does know how to find
+ the Python code thanks to :file:`pythonXY.lib`.
-The second command created :file:`ni.dll` (and :file:`.obj` and :file:`.lib`),
-which knows how to find the necessary functions from spam, and also from the
-Python executable.
+ The second command created :file:`ni.dll` (and :file:`.obj` and
+ :file:`.lib`), which knows how to find the necessary functions from spam,
+ and also from the Python executable.
Not every identifier is exported to the lookup table. If you want any other
modules (including Python) to be able to see your identifiers, you have to say
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index 2402fb23c86b85..054cfb177f268b 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -1415,6 +1415,10 @@ Build changes
* GNU Autoconf 2.72 is now required to generate :file:`configure`.
(Contributed by Erlend Aasland in :gh:`115765`.)
+* ``#pragma``-based linking with ``python3*.lib`` can now be switched off
+ with :c:expr:`Py_NO_LINK_LIB`. (Contributed by Jean-Christophe
+ Fillion-Robin in :gh:`82909`.)
+
.. _whatsnew314-pep761:
PEP 761: Discontinuation of PGP signatures
diff --git
a/Misc/NEWS.d/next/Build/2023-04-02-14-20-29.gh-issue-82909.LGcZJy.rst
b/Misc/NEWS.d/next/Build/2023-04-02-14-20-29.gh-issue-82909.LGcZJy.rst
new file mode 100644
index 00000000000000..0de47cf768c223
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2023-04-02-14-20-29.gh-issue-82909.LGcZJy.rst
@@ -0,0 +1,2 @@
+``#pragma``-based linking with ``python3*.lib`` can now be switched off with
+:c:expr:`Py_NO_LINK_LIB`. Patch by Jean-Christophe Fillion-Robin.
diff --git a/PC/pyconfig.h.in b/PC/pyconfig.h.in
index f4f57c5d270028..9e70303868e5de 100644
--- a/PC/pyconfig.h.in
+++ b/PC/pyconfig.h.in
@@ -311,9 +311,13 @@ Py_NO_ENABLE_SHARED to find out. Also support
MS_NO_COREDLL for b/w compat */
#ifdef MS_COREDLL
# if !defined(Py_BUILD_CORE) && !defined(Py_BUILD_CORE_BUILTIN)
/* not building the core - must be an ext */
-# if defined(_MSC_VER)
+# if defined(_MSC_VER) && !defined(Py_NO_LINK_LIB)
/* So MSVC users need not specify the .lib
file in their Makefile */
+ /* Define Py_NO_LINK_LIB to build extension disabling
pragma
+ based auto-linking.
+ This is relevant when using build-system generator
(e.g CMake) where
+ the linking is explicitly handled */
# if defined(Py_GIL_DISABLED)
# if defined(_DEBUG)
# pragma comment(lib,"python314t_d.lib")
@@ -331,7 +335,7 @@ Py_NO_ENABLE_SHARED to find out. Also support
MS_NO_COREDLL for b/w compat */
# pragma comment(lib,"python314.lib")
# endif /* _DEBUG */
# endif /* Py_GIL_DISABLED */
-# endif /* _MSC_VER */
+# endif /* _MSC_VER && !Py_NO_LINK_LIB */
# endif /* Py_BUILD_CORE */
#endif /* MS_COREDLL */
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