****************
Configure Python
****************
.. _configure-options:
Configure Options
=================
List all ``./configure`` script options using::
./configure --help
See also the :file:`Misc/SpecialBuilds.txt` in the Python source distribution.
General Options
---------------
.. cmdoption:: --enable-loadable-sqlite-extensions
Support loadable extensions in the :mod:`_sqlite` extension module (default
is no).
See the :meth:`sqlite3.Connection.enable_load_extension` method of the
:mod:`sqlite3` module.
.. versionadded:: 3.6
.. cmdoption:: --disable-ipv6
Disable IPv6 support (enabled by default if supported), see the
:mod:`socket` module.
.. cmdoption:: --enable-big-digits=[15|30]
Define the size in bits of Python :class:`int` digits: 15 or 30 bits.
By default, the digit size is 30.
Define the ``PYLONG_BITS_IN_DIGIT`` to ``15`` or ``30``.
See :data:`sys.int_info.bits_per_digit <sys.int_info>`.
.. cmdoption:: --with-cxx-main
.. cmdoption:: --with-cxx-main=COMPILER
Compile the Python ``main()`` function and link Python executable with C++
compiler: ``$CXX``, or *COMPILER* if specified.
.. cmdoption:: --with-suffix=SUFFIX
Set the Python executable suffix to *SUFFIX*.
The default suffix is ``.exe`` on Windows and macOS (``python.exe``
executable), ``.js`` on Emscripten node, ``.html`` on Emscripten browser,
``.wasm`` on WASI, and an empty string on other platforms (``python``
executable).
.. versionchanged:: 3.11
The default suffix on WASM platform is one of ``.js``, ``.html``
or ``.wasm``.
.. cmdoption:: --with-tzpath=<list of absolute paths separated by pathsep>
Select the default time zone search path for :data:`zoneinfo.TZPATH`.
See the :ref:`Compile-time configuration
<zoneinfo_data_compile_time_config>` of the :mod:`zoneinfo` module.
Default: ``/usr/share/zoneinfo:/usr/lib/zoneinfo:/usr/share/lib/zoneinfo:/etc/zoneinfo``.
See :data:`os.pathsep` path separator.
.. versionadded:: 3.9
.. cmdoption:: --without-decimal-contextvar
Build the ``_decimal`` extension module using a thread-local context rather
than a coroutine-local context (default), see the :mod:`decimal` module.
See :data:`decimal.HAVE_CONTEXTVAR` and the :mod:`contextvars` module.
.. versionadded:: 3.9
.. cmdoption:: --with-dbmliborder=<list of backend names>
Override order to check db backends for the :mod:`dbm` module
A valid value is a colon (``:``) separated string with the backend names:
* ``ndbm``;
* ``gdbm``;
* ``bdb``.
.. cmdoption:: --without-c-locale-coercion
Disable C locale coercion to a UTF-8 based locale (enabled by default).
Don't define the ``PY_COERCE_C_LOCALE`` macro.
See :envvar:`PYTHONCOERCECLOCALE` and the :pep:`538`.
.. cmdoption:: --with-platlibdir=DIRNAME
Python library directory name (default is ``lib``).
Fedora and SuSE use ``lib64`` on 64-bit platforms.
See :data:`sys.platlibdir`.
.. versionadded:: 3.9
.. cmdoption:: --with-wheel-pkg-dir=PATH
Directory of wheel packages used by the :mod:`ensurepip` module
(none by default).
Some Linux distribution packaging policies recommend against bundling
dependencies. For example, Fedora installs wheel packages in the
``/usr/share/python-wheels/`` directory and don't install the
:mod:`ensurepip._bundled` package.
.. versionadded:: 3.10
.. cmdoption:: --with-pkg-config=[check|yes|no]
Whether configure should use :program:`pkg-config` to detect build
dependencies.
* ``check`` (default): :program:`pkg-config` is optional
* ``yes``: :program:`pkg-config` is mandatory
* ``no``: configure does not use :program:`pkg-config` even when present
.. versionadded:: 3.11
.. cmdoption:: --enable-pystats
Turn on internal statistics gathering.
The statistics will be dumped to a arbitrary (probably unique) file in
``/tmp/py_stats/``, or ``C:\temp\py_stats\`` on Windows.
Use ``Tools/scripts/summarize_stats.py`` to read the stats.
.. versionadded:: 3.11
WebAssembly Options
-------------------
.. cmdoption:: --with-emscripten-target=[browser|node]
Set build flavor for ``wasm32-emscripten``.
* ``browser`` (default): preload minimal stdlib, default MEMFS.
* ``node``: NODERAWFS and pthread support.
.. versionadded:: 3.11
.. cmdoption:: --enable-wasm-dynamic-linking
Turn on dynamic linking support for WASM.
Dynamic linking enables ``dlopen``. File size of the executable
increases due to limited dead code elimination and additional features.
.. versionadded:: 3.11
.. cmdoption:: --enable-wasm-pthreads
Turn on pthreads support for WASM.
.. versionadded:: 3.11
Install Options
---------------
.. cmdoption:: --disable-test-modules
Don't build nor install test modules, like the :mod:`test` package or the
:mod:`_testcapi` extension module (built and installed by default).
.. versionadded:: 3.10
.. cmdoption:: --with-ensurepip=[upgrade|install|no]
Select the :mod:`ensurepip` command run on Python installation:
* ``upgrade`` (default): run ``python -m ensurepip --altinstall --upgrade``
command.
* ``install``: run ``python -m ensurepip --altinstall`` command;
* ``no``: don't run ensurepip;
.. versionadded:: 3.6
Performance options
-------------------
Configuring Python using ``--enable-optimizations --with-lto`` (PGO + LTO) is
recommended for best performance.
.. cmdoption:: --enable-optimizations
Enable Profile Guided Optimization (PGO) using :envvar:`PROFILE_TASK`
(disabled by default).
The C compiler Clang requires ``llvm-profdata`` program for PGO. On
macOS, GCC also requires it: GCC is just an alias to Clang on macOS.
Disable also semantic interposition in libpython if ``--enable-shared`` and
GCC is used: add ``-fno-semantic-interposition`` to the compiler and linker
flags.
.. versionadded:: 3.6
.. versionchanged:: 3.10
Use ``-fno-semantic-interposition`` on GCC.
.. envvar:: PROFILE_TASK
Environment variable used in the Makefile: Python command line arguments for
the PGO generation task.
Default: ``-m test --pgo --timeout=$(TESTTIMEOUT)``.
.. versionadded:: 3.8
.. cmdoption:: --with-lto=[full|thin|no|yes]
Enable Link Time Optimization (LTO) in any build (disabled by default).
The C compiler Clang requires ``llvm-ar`` for LTO (``ar`` on macOS), as well
as an LTO-aware linker (``ld.gold`` or ``lld``).
.. versionadded:: 3.6
.. versionadded:: 3.11
To use ThinLTO feature, use ``--with-lto=thin`` on Clang.
.. cmdoption:: --with-computed-gotos
Enable computed gotos in evaluation loop (enabled by default on supported
compilers).
.. cmdoption:: --without-pymalloc
Disable the specialized Python memory allocator :ref:`pymalloc <pymalloc>`
(enabled by default).
See also :envvar:`PYTHONMALLOC` environment variable.
.. cmdoption:: --without-doc-strings
Disable static documentation strings to reduce the memory footprint (enabled
by default). Documentation strings defined in Python are not affected.
Don't define the ``WITH_DOC_STRINGS`` macro.
See the ``PyDoc_STRVAR()`` macro.
.. cmdoption:: --enable-profiling
Enable C-level code profiling with ``gprof`` (disabled by default).
.. _debug-build:
Python Debug Build
------------------
A debug build is Python built with the :option:`--with-pydebug` configure
option.
Effects of a debug build:
* Display all warnings by default: the list of default warning filters is empty
in the :mod:`warnings` module.
* Add ``d`` to :data:`sys.abiflags`.
* Add :func:`sys.gettotalrefcount` function.
* Add :option:`-X showrefcount <-X>` command line option.
* Add :envvar:`PYTHONTHREADDEBUG` environment variable.
* Add support for the ``__lltrace__`` variable: enable low-level tracing in the
bytecode evaluation loop if the variable is defined.
* Install :ref:`debug hooks on memory allocators <default-memory-allocators>`
to detect buffer overflow and other memory errors.
* Define ``Py_DEBUG`` and ``Py_REF_DEBUG`` macros.
* Add runtime checks: code surrounded by ``#ifdef Py_DEBUG`` and ``#endif``.
Enable ``assert(...)`` and ``_PyObject_ASSERT(...)`` assertions: don't set
the ``NDEBUG`` macro (see also the :option:`--with-assertions` configure
option). Main runtime checks:
* Add sanity checks on the function arguments.
* Unicode and int objects are created with their memory filled with a pattern
to detect usage of uninitialized objects.
* Ensure that functions which can clear or replace the current exception are
not called with an exception raised.
* Check that deallocator functions don't change the current exception.
* The garbage collector (:func:`gc.collect` function) runs some basic checks
on objects consistency.
* The :c:macro:`Py_SAFE_DOWNCAST()` macro checks for integer underflow and
overflow when downcasting from wide types to narrow types.
See also the :ref:`Python Development Mode <devmode>` and the
:option:`--with-trace-refs` configure option.
.. versionchanged:: 3.8
Release builds and debug builds are now ABI compatible: defining the
``Py_DEBUG`` macro no longer implies the ``Py_TRACE_REFS`` macro (see the
:option:`--with-trace-refs` option), which introduces the only ABI
incompatibility.
Debug options
-------------
.. cmdoption:: --with-pydebug
:ref:`Build Python in debug mode <debug-build>`: define the ``Py_DEBUG``
macro (disabled by default).
.. cmdoption:: --with-trace-refs
Enable tracing references for debugging purpose (disabled by default).
Effects:
* Define the ``Py_TRACE_REFS`` macro.
* Add :func:`sys.getobjects` function.
* Add :envvar:`PYTHONDUMPREFS` environment variable.
This build is not ABI compatible with release build (default build) or debug
build (``Py_DEBUG`` and ``Py_REF_DEBUG`` macros).
.. versionadded:: 3.8
.. cmdoption:: --with-assertions
Build with C assertions enabled (default is no): ``assert(...);`` and
``_PyObject_ASSERT(...);``.
If set, the ``NDEBUG`` macro is not defined in the :envvar:`OPT` compiler
variable.
See also the :option:`--with-pydebug` option (:ref:`debug build
<debug-build>`) which also enables assertions.
.. versionadded:: 3.6
.. cmdoption:: --with-valgrind
Enable Valgrind support (default is no).
.. cmdoption:: --with-dtrace
Enable DTrace support (default is no).
See :ref:`Instrumenting CPython with DTrace and SystemTap
<instrumentation>`.
.. versionadded:: 3.6
.. cmdoption:: --with-address-sanitizer
Enable AddressSanitizer memory error detector, ``asan`` (default is no).
.. versionadded:: 3.6
.. cmdoption:: --with-memory-sanitizer
Enable MemorySanitizer allocation error detector, ``msan`` (default is no).
.. versionadded:: 3.6
.. cmdoption:: --with-undefined-behavior-sanitizer
Enable UndefinedBehaviorSanitizer undefined behaviour detector, ``ubsan``
(default is no).
.. versionadded:: 3.6
Linker options
--------------
.. cmdoption:: --enable-shared
Enable building a shared Python library: ``libpython`` (default is no).
.. cmdoption:: --without-static-libpython
Do not build ``libpythonMAJOR.MINOR.a`` and do not install ``python.o``
(built and enabled by default).
.. versionadded:: 3.10
Libraries options
-----------------
.. cmdoption:: --with-libs='lib1 ...'
Link against additional libraries (default is no).
.. cmdoption:: --with-system-expat
Build the :mod:`pyexpat` module using an installed ``expat`` library
(default is no).
.. cmdoption:: --with-system-ffi
Build the :mod:`_ctypes` extension module using an installed ``ffi``
library, see the :mod:`ctypes` module (default is system-dependent).
.. cmdoption:: --with-system-libmpdec
Build the ``_decimal`` extension module using an installed ``mpdec``
library, see the :mod:`decimal` module (default is no).
.. versionadded:: 3.3
.. cmdoption:: --with-readline=editline
Use ``editline`` library for backend of the :mod:`readline` module.
Define the ``WITH_EDITLINE`` macro.
.. versionadded:: 3.10
.. cmdoption:: --without-readline
Don't build the :mod:`readline` module (built by default).
Don't define the ``HAVE_LIBREADLINE`` macro.
.. versionadded:: 3.10
.. cmdoption:: --with-libm=STRING
Override ``libm`` math library to *STRING* (default is system-dependent).
.. cmdoption:: --with-libc=STRING
Override ``libc`` C library to *STRING* (default is system-dependent).
.. cmdoption:: --with-openssl=DIR
Root of the OpenSSL directory.
.. versionadded:: 3.7
.. cmdoption:: --with-openssl-rpath=[no|auto|DIR]
Set runtime library directory (rpath) for OpenSSL libraries:
* ``no`` (default): don't set rpath;
* ``auto``: auto-detect rpath from :option:`--with-openssl` and
``pkg-config``;
* *DIR*: set an explicit rpath.
.. versionadded:: 3.10
Security Options
----------------
.. cmdoption:: --with-hash-algorithm=[fnv|siphash13|siphash24]
Select hash algorithm for use in ``Python/pyhash.c``:
* ``siphash13`` (default);
* ``siphash24``;
* ``fnv``.
.. versionadded:: 3.4
.. versionadded:: 3.11
``siphash13`` is added and it is the new default.
.. cmdoption:: --with-builtin-hashlib-hashes=md5,sha1,sha256,sha512,sha3,blake2
Built-in hash modules:
* ``md5``;
* ``sha1``;
* ``sha256``;
* ``sha512``;
* ``sha3`` (with shake);
* ``blake2``.
.. versionadded:: 3.9
.. cmdoption:: --with-ssl-default-suites=[python|openssl|STRING]
Override the OpenSSL default cipher suites string:
* ``python`` (default): use Python's preferred selection;
* ``openssl``: leave OpenSSL's defaults untouched;
* *STRING*: use a custom string
See the :mod:`ssl` module.
.. versionadded:: 3.7
.. versionchanged:: 3.10
The settings ``python`` and *STRING* also set TLS 1.2 as minimum
protocol version.
macOS Options
-------------
See ``Mac/README.rst``.
.. cmdoption:: --enable-universalsdk
.. cmdoption:: --enable-universalsdk=SDKDIR
Create a universal binary build. *SDKDIR* specifies which macOS SDK should
be used to perform the build (default is no).
.. cmdoption:: --enable-framework
.. cmdoption:: --enable-framework=INSTALLDIR
Create a Python.framework rather than a traditional Unix install. Optional
*INSTALLDIR* specifies the installation path (default is no).
.. cmdoption:: --with-universal-archs=ARCH
Specify the kind of universal binary that should be created. This option is
only valid when :option:`--enable-universalsdk` is set.
Options:
* ``universal2``;
* ``32-bit``;
* ``64-bit``;
* ``3-way``;
* ``intel``;
* ``intel-32``;
* ``intel-64``;
* ``all``.
.. cmdoption:: --with-framework-name=FRAMEWORK
Specify the name for the python framework on macOS only valid when
:option:`--enable-framework` is set (default: ``Python``).
Cross Compiling Options
-----------------------
Cross compiling, also known as cross building, can be used to build Python
for another CPU architecture or platform. Cross compiling requires a Python
interpreter for the build platform. The version of the build Python must match
the version of the cross compiled host Python.
.. cmdoption:: --build=BUILD
configure for building on BUILD, usually guessed by :program:`config.guess`.
.. cmdoption:: --host=HOST
cross-compile to build programs to run on HOST (target platform)
.. cmdoption:: --with-build-python=path/to/python
path to build ``python`` binary for cross compiling
.. versionadded:: 3.11
.. cmdoption:: CONFIG_SITE=file
An environment variable that points to a file with configure overrides.
Example *config.site* file::
# config.site-aarch64
ac_cv_buggy_getaddrinfo=no
ac_cv_file__dev_ptmx=yes
ac_cv_file__dev_ptc=no
Cross compiling example::
CONFIG_SITE=config.site-aarch64 ../configure \
--build=x86_64-pc-linux-gnu \
--host=aarch64-unknown-linux-gnu \
--with-build-python=../x86_64/python
Python Build System
===================
Main files of the build system
------------------------------
* :file:`configure.ac` => :file:`configure`;
* :file:`Makefile.pre.in` => :file:`Makefile` (created by :file:`configure`);
* :file:`pyconfig.h` (created by :file:`configure`);
* :file:`Modules/Setup`: C extensions built by the Makefile using
:file:`Module/makesetup` shell script;
* :file:`setup.py`: C extensions built using the :mod:`distutils` module.
Main build steps
----------------
* C files (``.c``) are built as object files (``.o``).
* A static ``libpython`` library (``.a``) is created from objects files.
* ``python.o`` and the static ``libpython`` library are linked into the
final ``python`` program.
* C extensions are built by the Makefile (see :file:`Modules/Setup`)
and ``python setup.py build``.
Main Makefile targets
---------------------
* ``make``: Build Python with the standard library.
* ``make platform:``: build the ``python`` program, but don't build the
standard library extension modules.
* ``make profile-opt``: build Python using Profile Guided Optimization (PGO).
You can use the configure :option:`--enable-optimizations` option to make
this the default target of the ``make`` command (``make all`` or just
``make``).
* ``make buildbottest``: Build Python and run the Python test suite, the same
way than buildbots test Python. Set ``TESTTIMEOUT`` variable (in seconds)
to change the test timeout (1200 by default: 20 minutes).
* ``make install``: Build and install Python.
* ``make regen-all``: Regenerate (almost) all generated files;
``make regen-stdlib-module-names`` and ``autoconf`` must be run separately
for the remaining generated files.
* ``make clean``: Remove built files.
* ``make distclean``: Same than ``make clean``, but remove also files created
by the configure script.
C extensions
------------
Some C extensions are built as built-in modules, like the ``sys`` module.
They are built with the ``Py_BUILD_CORE_BUILTIN`` macro defined.
Built-in modules have no ``__file__`` attribute::
>>> import sys
>>> sys
<module 'sys' (built-in)>
>>> sys.__file__
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: module 'sys' has no attribute '__file__'
Other C extensions are built as dynamic libraries, like the ``_asyncio`` module.
They are built with the ``Py_BUILD_CORE_MODULE`` macro defined.
Example on Linux x86-64::
>>> import _asyncio
>>> _asyncio
<module '_asyncio' from '/usr/lib64/python3.9/lib-dynload/_asyncio.cpython-39-x86_64-linux-gnu.so'>
>>> _asyncio.__file__
'/usr/lib64/python3.9/lib-dynload/_asyncio.cpython-39-x86_64-linux-gnu.so'
:file:`Modules/Setup` is used to generate Makefile targets to build C extensions.
At the beginning of the files, C extensions are built as built-in modules.
Extensions defined after the ``*shared*`` marker are built as dynamic libraries.
The :file:`setup.py` script only builds C extensions as shared libraries using
the :mod:`distutils` module.
The :c:macro:`PyAPI_FUNC()`, :c:macro:`PyAPI_API()` and
:c:macro:`PyMODINIT_FUNC()` macros of :file:`Include/pyport.h` are defined
differently depending if the ``Py_BUILD_CORE_MODULE`` macro is defined:
* Use ``Py_EXPORTED_SYMBOL`` if the ``Py_BUILD_CORE_MODULE`` is defined
* Use ``Py_IMPORTED_SYMBOL`` otherwise.
If the ``Py_BUILD_CORE_BUILTIN`` macro is used by mistake on a C extension
built as a shared library, its ``PyInit_xxx()`` function is not exported,
causing an :exc:`ImportError` on import.
Compiler and linker flags
=========================
Options set by the ``./configure`` script and environment variables and used by
``Makefile``.
Preprocessor flags
------------------
.. envvar:: CONFIGURE_CPPFLAGS
Value of :envvar:`CPPFLAGS` variable passed to the ``./configure`` script.
.. versionadded:: 3.6
.. envvar:: CPPFLAGS
(Objective) C/C++ preprocessor flags, e.g. ``-I<include dir>`` if you have
headers in a nonstandard directory ``<include dir>``.
Both :envvar:`CPPFLAGS` and :envvar:`LDFLAGS` need to contain the shell's
value for setup.py to be able to build extension modules using the
directories specified in the environment variables.
.. envvar:: BASECPPFLAGS
.. versionadded:: 3.4
.. envvar:: PY_CPPFLAGS
Extra preprocessor flags added for building the interpreter object files.
Default: ``$(BASECPPFLAGS) -I. -I$(srcdir)/Include $(CONFIGURE_CPPFLAGS) $(CPPFLAGS)``.
.. versionadded:: 3.2
Compiler flags
--------------
.. envvar:: CC
C compiler command.
Example: ``gcc -pthread``.
.. envvar:: MAINCC
C compiler command used to build the ``main()`` function of programs like
``python``.
Variable set by the :option:`--with-cxx-main` option of the configure
script.
Default: ``$(CC)``.
.. envvar:: CXX
C++ compiler command.
Used if the :option:`--with-cxx-main` option is used.
Example: ``g++ -pthread``.
.. envvar:: CFLAGS
C compiler flags.
.. envvar:: CFLAGS_NODIST
:envvar:`CFLAGS_NODIST` is used for building the interpreter and stdlib C
extensions. Use it when a compiler flag should *not* be part of the
distutils :envvar:`CFLAGS` once Python is installed (:issue:`21121`).
In particular, :envvar:`CFLAGS` should not contain:
* the compiler flag ``-I`` (for setting the search path for include files).
The ``-I`` flags are processed from left to right, and any flags in
:envvar:`CFLAGS` would take precedence over user- and package-supplied ``-I``
flags.
* hardening flags such as ``-Werror`` because distributions cannot control
whether packages installed by users conform to such heightened
standards.
.. versionadded:: 3.5
.. envvar:: EXTRA_CFLAGS
Extra C compiler flags.
.. envvar:: CONFIGURE_CFLAGS
Value of :envvar:`CFLAGS` variable passed to the ``./configure``
script.
.. versionadded:: 3.2
.. envvar:: CONFIGURE_CFLAGS_NODIST
Value of :envvar:`CFLAGS_NODIST` variable passed to the ``./configure``
script.
.. versionadded:: 3.5
.. envvar:: BASECFLAGS
Base compiler flags.
.. envvar:: OPT
Optimization flags.
.. envvar:: CFLAGS_ALIASING
Strict or non-strict aliasing flags used to compile ``Python/dtoa.c``.
.. versionadded:: 3.7
.. envvar:: CCSHARED
Compiler flags used to build a shared library.
For example, ``-fPIC`` is used on Linux and on BSD.
.. envvar:: CFLAGSFORSHARED
Extra C flags added for building the interpreter object files.
Default: ``$(CCSHARED)`` when :option:`--enable-shared` is used, or an empty
string otherwise.
.. envvar:: PY_CFLAGS
Default: ``$(BASECFLAGS) $(OPT) $(CONFIGURE_CFLAGS) $(CFLAGS) $(EXTRA_CFLAGS)``.
.. envvar:: PY_CFLAGS_NODIST
Default: ``$(CONFIGURE_CFLAGS_NODIST) $(CFLAGS_NODIST) -I$(srcdir)/Include/internal``.
.. versionadded:: 3.5
.. envvar:: PY_STDMODULE_CFLAGS
C flags used for building the interpreter object files.
Default: ``$(PY_CFLAGS) $(PY_CFLAGS_NODIST) $(PY_CPPFLAGS) $(CFLAGSFORSHARED)``.
.. versionadded:: 3.7
.. envvar:: PY_CORE_CFLAGS
Default: ``$(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE``.
.. versionadded:: 3.2
.. envvar:: PY_BUILTIN_MODULE_CFLAGS
Compiler flags to build a standard library extension module as a built-in
module, like the :mod:`posix` module.
Default: ``$(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE_BUILTIN``.
.. versionadded:: 3.8
.. envvar:: PURIFY
Purify command. Purify is a memory debugger program.
Default: empty string (not used).
Linker flags
------------
.. envvar:: LINKCC
Linker command used to build programs like ``python`` and ``_testembed``.
Default: ``$(PURIFY) $(MAINCC)``.
.. envvar:: CONFIGURE_LDFLAGS
Value of :envvar:`LDFLAGS` variable passed to the ``./configure`` script.
Avoid assigning :envvar:`CFLAGS`, :envvar:`LDFLAGS`, etc. so users can use
them on the command line to append to these values without stomping the
pre-set values.
.. versionadded:: 3.2
.. envvar:: LDFLAGS_NODIST
:envvar:`LDFLAGS_NODIST` is used in the same manner as
:envvar:`CFLAGS_NODIST`. Use it when a linker flag should *not* be part of
the distutils :envvar:`LDFLAGS` once Python is installed (:issue:`35257`).
In particular, :envvar:`LDFLAGS` should not contain:
* the compiler flag ``-L`` (for setting the search path for libraries).
The ``-L`` flags are processed from left to right, and any flags in
:envvar:`LDFLAGS` would take precedence over user- and package-supplied ``-L``
flags.
.. envvar:: CONFIGURE_LDFLAGS_NODIST
Value of :envvar:`LDFLAGS_NODIST` variable passed to the ``./configure``
script.
.. versionadded:: 3.8
.. envvar:: LDFLAGS
Linker flags, e.g. ``-L<lib dir>`` if you have libraries in a nonstandard
directory ``<lib dir>``.
Both :envvar:`CPPFLAGS` and :envvar:`LDFLAGS` need to contain the shell's
value for setup.py to be able to build extension modules using the
directories specified in the environment variables.
.. envvar:: LIBS
Linker flags to pass libraries to the linker when linking the Python
executable.
Example: ``-lrt``.
.. envvar:: LDSHARED
Command to build a shared library.
Default: ``@LDSHARED@ $(PY_LDFLAGS)``.
.. envvar:: BLDSHARED
Command to build ``libpython`` shared library.
Default: ``@BLDSHARED@ $(PY_CORE_LDFLAGS)``.
.. envvar:: PY_LDFLAGS
Default: ``$(CONFIGURE_LDFLAGS) $(LDFLAGS)``.
.. envvar:: PY_LDFLAGS_NODIST
Default: ``$(CONFIGURE_LDFLAGS_NODIST) $(LDFLAGS_NODIST)``.
.. versionadded:: 3.8
.. envvar:: PY_CORE_LDFLAGS
Linker flags used for building the interpreter object files.
.. versionadded:: 3.8
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