3. Configurer Python
********************


3.1. Build Requirements
=======================

Features required to build CPython:

* A C11 compiler. Optional C11 features are not required.

* Support for IEEE 754 floating point numbers and floating point
  Not-a-Number (NaN).

* Support for threads.

* OpenSSL 1.1.1 or newer for the "ssl" and "hashlib" modules.

* On Windows, Microsoft Visual Studio 2017 or later is required.

Modifié dans la version 3.5: On Windows, Visual Studio 2015 or later
is required.

Modifié dans la version 3.6: Selected C99 features are now required,
like "<stdint.h>" and "static inline" functions.

Modifié dans la version 3.7: Thread support and OpenSSL 1.0.2 are now
required.

Modifié dans la version 3.10: OpenSSL 1.1.1 is now required.

Modifié dans la version 3.11: C11 compiler, IEEE 754 and NaN support
are now required. On Windows, Visual Studio 2017 or later is required.

See also **PEP 7** "Style Guide for C Code" and **PEP 11** "CPython
platform support".


3.2. Generated files
====================

To reduce build dependencies, Python source code contains multiple
generated files. Commands to regenerate all generated files:

   make regen-all
   make regen-stdlib-module-names
   make regen-limited-abi
   make regen-configure

The "Makefile.pre.in" file documents generated files, their inputs,
and tools used to regenerate them. Search for "regen-*" make targets.


3.2.1. configure script
-----------------------

The "make regen-configure" command regenerates the "aclocal.m4" file
and the "configure" script using the "Tools/build/regen-configure.sh"
shell script which uses an Ubuntu container to get the same tools
versions and have a reproducible output.

The container is optional, the following command can be run locally:

   autoreconf -ivf -Werror

The generated files can change depending on the exact "autoconf-
archive", "aclocal" and "pkg-config" versions.


3.3. Options de configuration
=============================

Il est possible d'obtenir toutes les options de "./configure" avec :

   ./configure --help

Voir aussi le fichier "Misc/SpecialBuilds.txt" dans la distribution
des sources Python.


3.3.1. Options générales
------------------------

--enable-loadable-sqlite-extensions

   Support loadable extensions in the "_sqlite" extension module
   (default is no) of the "sqlite3" module.

   Voir la méthode  "sqlite3.Connection.enable_load_extension()" du
   module "sqlite3".

   Added in version 3.6.

--disable-ipv6

   Désactive la prise en charge d'IPv6 (activé par défaut si géré),
   voir le module "socket".

--enable-big-digits=[15|30]

   Définit la taille en bits des chiffres Python "int" : 15 ou 30
   bits.

   La valeur par défaut est "30" bits.

   Définit "PYLONG_BITS_IN_DIGIT" à "15" ou "30".

   Voir "sys.int_info.bits_per_digit".

--with-suffix=SUFFIX

   Définit à *SUFFIX* le suffixe de l'exécutable Python.

   Le suffixe par défaut est ".exe" sur Windows et macOS (exécutable
   "python.exe"), ".js" pour Emscripten ("node"), ".html" pour
   Emscripten (navigateur), ".wasm" pour WASI, et une chaîne vide sur
   les autres plateformes (exécutable "python").

   Modifié dans la version 3.11: les suffixes par défaut pour la
   plateforme WASM sont maintenant ".js", ".html" et ".wasm".

--with-tzpath=<list of absolute paths separated by pathsep>

   Select the default time zone search path for "zoneinfo.TZPATH". See
   the Compile-time configuration of the "zoneinfo" module.

   Par défaut : "/usr/share/zoneinfo:/usr/lib/zoneinfo:/usr/share/lib
   /zoneinfo:/etc/zoneinfo".

   Voir le séparateur de chemins "os.pathsep".

   Added in version 3.9.

--without-decimal-contextvar

   Compile le module d'extension "_decimal" en utilisant un contexte
   local au fil d'exécution plutôt qu'un contexte local de coroutine
   (défaut). Voir le module "decimal".

   See "decimal.HAVE_CONTEXTVAR" and the "contextvars" module.

   Added in version 3.9.

--with-dbmliborder=<list of backend names>

   Change l'ordre de détection des implémentations de base de données
   pour le module "dbm".

   Une valeur valide est une chaîne de noms d'implémentations séparés
   par des deux-points (":") :

   * "ndbm" ;

   * "gdbm" ;

   * "bdb".

--without-c-locale-coercion

   Désactive le forçage des paramètres régionaux C pour un paramètre
   régional basé sur UTF-8 (activé par défaut).

   Ne pas définir la macro "PY_COERCE_C_LOCALE".

   Voir "PYTHONCOERCECLOCALE" et la **PEP 538**.

--without-freelists

   Disable all freelists except the empty tuple singleton.

   Added in version 3.11.

--with-platlibdir=DIRNAME

   Nom du dossier de bibliothèques Python (par défaut : "lib").

   Fedora et SuSE utilisent "lib64" sur les systèmes 64-bit.

   Voir "sys.platlibdir".

   Added in version 3.9.

--with-wheel-pkg-dir=PATH

   Dossier de paquets *wheel* utilisé par le module "ensurepip" (par
   défaut : aucun).

   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
   "ensurepip._bundled" package.

   Added in version 3.10.

--with-pkg-config=[check|yes|no]

   Est-ce que *configure* doit utiliser **pkg-config** pour détecter
   les dépendances de construction.

   * "check" (par défaut) : **pkg-config** est optionnel

   * "yes" : **pkg-config** est obligatoire

   * "no" : *configure* n'utilise pas **pkg-config** même s'il est
     présent

   Added in version 3.11.

--enable-pystats

   Active la collecte des statistiques internes.

   The statistics will be dumped to a arbitrary (probably unique) file
   in "/tmp/py_stats/", or "C:\temp\py_stats\" on Windows. If that
   directory does not exist, results will be printed on stdout.

   Utilisez "Tools/scripts/summarize_stats.py" pour lire les
   statistiques.

   Added in version 3.11.


3.3.2. Options de WebAssembly
-----------------------------

--with-emscripten-target=[browser|node]

   Définit la version de construction pour "wasm32-emscripten".

   * "browser" (par défaut) : précharge une version minimale de la
     *stdlib*, par défaut MEMFS.

   * "node": NODERAWFS et la gestion des *pthread*.

   Added in version 3.11.

--enable-wasm-dynamic-linking

   Active la gestion d'édition de liens dynamique pour WASM

   L'édition de liens dynamique autorise "dlopen". La taille du
   fichier exécutable augmente en raison de l'élimination moindre du
   code mort et des fonctionnalités supplémentaires.

   Added in version 3.11.

--enable-wasm-pthreads

   Active la gestion des *pthreads* pour WASM.

   Added in version 3.11.


3.3.3. Options d'installation
-----------------------------

--prefix=PREFIX

   Install architecture-independent files in PREFIX. On Unix, it
   defaults to "/usr/local".

   This value can be retrieved at runtime using "sys.prefix".

   As an example, one can use "--prefix="$HOME/.local/"" to install a
   Python in its home directory.

--exec-prefix=EPREFIX

   Install architecture-dependent files in EPREFIX, defaults to "--
   prefix".

   This value can be retrieved at runtime using "sys.exec_prefix".

--disable-test-modules

   Don't build nor install test modules, like the "test" package or
   the "_testcapi" extension module (built and installed by default).

   Added in version 3.10.

--with-ensurepip=[upgrade|install|no]

   Sélectionne la commande "ensurepip" exécutée à l'installation de
   Python :

   * "upgrade" (défaut) : exécute la commande "python -m ensurepip
     --altinstall --upgrade" ;

   * "install" : exécute la commande "python -m ensurepip
     --altinstall" ;

   * "no" : n'exécute pas *ensurepip*.

   Added in version 3.6.


3.3.4. Options de performance
-----------------------------

Configuring Python using "--enable-optimizations --with-lto" (PGO +
LTO) is recommended for best performance. The experimental "--enable-
bolt" flag can also be used to improve performance.

--enable-optimizations

   Active l'optimisation guidée par profilage (*Profile Guided
   Optimization*, PGO) en utilisant "PROFILE_TASK" (désactivé par
   défaut).

   L'utilisation de PGO avec le compilateur C Clang nécessite "llvm-
   profdata". Sur macOS, GCC est juste un alias vers Clang et partage
   donc cette contrainte.

   Désactive également l'interposition sémantique dans *libpython* si
   GCC est utilisé avec "--enable-shared" : ajoute l'option "-fno-
   semantic-interposition" à la compilation et à l'édition des liens.

   Note:

     During the build, you may encounter compiler warnings about
     profile data not being available for some source files. These
     warnings are harmless, as only a subset of the code is exercised
     during profile data acquisition. To disable these warnings on
     Clang, manually suppress them by adding "-Wno-profile-instr-
     unprofiled" to "CFLAGS".

   Added in version 3.6.

   Modifié dans la version 3.10: Utilisation de "-fno-semantic-
   interposition" avec GCC.

PROFILE_TASK

   Variable d'environnement utilisée dans le "Makefile" : arguments
   Python utilisés pour la tâche de préparation de la PGO.

   Par défaut : "-m test --pgo --timeout=$(TESTTIMEOUT)".

   Added in version 3.8.

--with-lto=[full|thin|no|yes]

   Active l'optimisation à l'édition des liens (*Link Time
   Optimization*, LTO) à la compilation (désactivé par défaut).

   Le compilateur C Clang nécessite "llvm-ar" pour la LTO ("ar" sur
   macOS), ainsi qu'un éditeur de liens implémentant la LTO ("ld.gold"
   ou "lld").

   Added in version 3.6.

   Added in version 3.11: Pour avoir la fonctionnalité ThinLTO,
   utilisez "--with-lto=thin" avec Clang.

   Modifié dans la version 3.12: Use ThinLTO as the default
   optimization policy on Clang if the compiler accepts the flag.

--enable-bolt

   Enable usage of the BOLT post-link binary optimizer (disabled by
   default).

   BOLT is part of the LLVM project but is not always included in
   their binary distributions. This flag requires that "llvm-bolt" and
   "merge-fdata" are available.

   BOLT is still a fairly new project so this flag should be
   considered experimental for now. Because this tool operates on
   machine code its success is dependent on a combination of the build
   environment + the other optimization configure args + the CPU
   architecture, and not all combinations are supported. BOLT versions
   before LLVM 16 are known to crash BOLT under some scenarios. Use of
   LLVM 16 or newer for BOLT optimization is strongly encouraged.

   The "BOLT_INSTRUMENT_FLAGS" and "BOLT_APPLY_FLAGS" **configure**
   variables can be defined to override the default set of arguments
   for **llvm-bolt** to instrument and apply BOLT data to binaries,
   respectively.

   Added in version 3.12.

--with-computed-gotos

   Autorise les *gotos* calculés dans les boucles (activé par défaut
   pour les compilateurs qui le gèrent).

--without-pymalloc

   Désactive l'allocateur spécialisé de mémoire de Python pymalloc
   (activé par défaut).

   Voir aussi la variable d'environnement "PYTHONMALLOC".

--without-doc-strings

   Désactive les chaînes de documentation statiques pour réduire
   l'empreinte mémoire (activé par défaut). Les chaînes définies dans
   Python ne sont pas affectées.

   Ne définit pas la macro "WITH_DOC_STRINGS".

   Voir la macro "PyDoc_STRVAR()".

--enable-profiling

   Active le profilage du code C avec "gprof" (désactivé par défaut).

--with-strict-overflow

   Add "-fstrict-overflow" to the C compiler flags (by default we add
   "-fno-strict-overflow" instead).


3.3.5. Compilation de Python en mode débogage
---------------------------------------------

Une compilation de Python en mode débogage se fait avec l'option de
configuration "--with-pydebug".

Effets du mode débogage :

* Affichage de tous les avertissements par défaut : le filtre par
  défaut des avertissements est vide dans le module "warnings".

* Ajout de "d" à "sys.abiflags".

* Add "sys.gettotalrefcount()" function.

* Ajout de l'option de ligne de commande "-X showrefcount".

* Add "-d" command line option and "PYTHONDEBUG" environment variable
  to debug the parser.

* Prise en charge de la variable "__ltrace__" : si la variable est
  définie, active le traçage de bas niveau dans la boucle d'évaluation
  du code intermédiaire.

* Installation des debug hooks on memory allocators pour détecter les
  débordements de mémoire tampon et autres erreurs de mémoire.

* Définition des macros "Py_DEBUG" et "Py_REF_DEBUG".

* Ajout de vérifications à l'exécution : codes entourés de "#ifdef
  Py_DEBUG" et "#endif". Active les assertions "assert(...)" et
  "_PyObject_ASSERT(...)" : ne définit pas la macro "NDEBUG" (voir
  aussi l'option de configuration "--with-assertions"). Les
  principales vérifications à l'exécution :

  * Ajout des contrôles d'intégrité sur les arguments de fonction.

  * Les objets "unicode" et "int" sont créés avec un motif particulier
    à l'initialisation de leur mémoire afin de détecter l'usage
    d'objets non initialisés.

  * S'assurer que les fonctions qui peuvent effacer ou remplacer
    l'exception courante ne sont pas appelées avec une exception
    levée.

  * S'assurer que les fonctions qui désallouent ne changent pas
    l'exception en cours.

  * Le ramasse-miettes (la fonction "gc.collect()") effectue quelques
    tests basiques relatifs à la cohérence des objets.

  * The "Py_SAFE_DOWNCAST()" macro checks for integer underflow and
    overflow when downcasting from wide types to narrow types.

Voir aussi le mode de développement Python et l'option de
configuration "--with-trace-refs".

Modifié dans la version 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 "--with-trace-refs" option), which
introduces the only ABI incompatibility.


3.3.6. Debug options
--------------------

--with-pydebug

   Build Python in debug mode: define the "Py_DEBUG" macro (disabled
   by default).

--with-trace-refs

   Enable tracing references for debugging purpose (disabled by
   default).

   Effects:

   * Define the "Py_TRACE_REFS" macro.

   * Add "sys.getobjects()" function.

   * Add "PYTHONDUMPREFS" environment variable.

   This build is not ABI compatible with release build (default build)
   or debug build ("Py_DEBUG" and "Py_REF_DEBUG" macros).

   Added in version 3.8.

--with-assertions

   Build with C assertions enabled (default is no): "assert(...);" and
   "_PyObject_ASSERT(...);".

   If set, the "NDEBUG" macro is not defined in the "OPT" compiler
   variable.

   See also the "--with-pydebug" option (debug build) which also
   enables assertions.

   Added in version 3.6.

--with-valgrind

   Enable Valgrind support (default is no).

--with-dtrace

   Enable DTrace support (default is no).

   See Instrumenting CPython with DTrace and SystemTap.

   Added in version 3.6.

--with-address-sanitizer

   Enable AddressSanitizer memory error detector, "asan" (default is
   no).

   Added in version 3.6.

--with-memory-sanitizer

   Enable MemorySanitizer allocation error detector, "msan" (default
   is no).

   Added in version 3.6.

--with-undefined-behavior-sanitizer

   Enable UndefinedBehaviorSanitizer undefined behaviour detector,
   "ubsan" (default is no).

   Added in version 3.6.


3.3.7. Linker options
---------------------

--enable-shared

   Enable building a shared Python library: "libpython" (default is
   no).

--without-static-libpython

   Do not build "libpythonMAJOR.MINOR.a" and do not install "python.o"
   (built and enabled by default).

   Added in version 3.10.


3.3.8. Libraries options
------------------------

--with-libs='lib1 ...'

   Link against additional libraries (default is no).

--with-system-expat

   Build the "pyexpat" module using an installed "expat" library
   (default is no).

--with-system-libmpdec

   Build the "_decimal" extension module using an installed "mpdec"
   library, see the "decimal" module (default is no).

   Added in version 3.3.

--with-readline=editline

   Use "editline" library for backend of the "readline" module.

   Define the "WITH_EDITLINE" macro.

   Added in version 3.10.

--without-readline

   Don't build the "readline" module (built by default).

   Don't define the "HAVE_LIBREADLINE" macro.

   Added in version 3.10.

--with-libm=STRING

   Override "libm" math library to *STRING* (default is system-
   dependent).

--with-libc=STRING

   Override "libc" C library to *STRING* (default is system-
   dependent).

--with-openssl=DIR

   Root of the OpenSSL directory.

   Added in version 3.7.

--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 "--with-openssl" and "pkg-config";

   * *DIR*: set an explicit rpath.

   Added in version 3.10.


3.3.9. Security Options
-----------------------

--with-hash-algorithm=[fnv|siphash13|siphash24]

   Select hash algorithm for use in "Python/pyhash.c":

   * "siphash13" (default);

   * "siphash24";

   * "fnv".

   Added in version 3.4.

   Added in version 3.11: "siphash13" is added and it is the new
   default.

--with-builtin-hashlib-hashes=md5,sha1,sha256,sha512,sha3,blake2

   Built-in hash modules:

   * "md5";

   * "sha1";

   * "sha256";

   * "sha512";

   * "sha3" (with shake);

   * "blake2".

   Added in version 3.9.

--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 "ssl" module.

   Added in version 3.7.

   Modifié dans la version 3.10: The settings "python" and *STRING*
   also set TLS 1.2 as minimum protocol version.


3.3.10. macOS Options
---------------------

See "Mac/README.rst".

--enable-universalsdk

--enable-universalsdk=SDKDIR

   Create a universal binary build. *SDKDIR* specifies which macOS SDK
   should be used to perform the build (default is no).

--enable-framework

--enable-framework=INSTALLDIR

   Create a Python.framework rather than a traditional Unix install.
   Optional *INSTALLDIR* specifies the installation path (default is
   no).

--with-universal-archs=ARCH

   Specify the kind of universal binary that should be created. This
   option is only valid when "--enable-universalsdk" is set.

   Options:

   * "universal2";

   * "32-bit";

   * "64-bit";

   * "3-way";

   * "intel";

   * "intel-32";

   * "intel-64";

   * "all".

--with-framework-name=FRAMEWORK

   Specify the name for the python framework on macOS only valid when
   "--enable-framework" is set (default: "Python").


3.3.11. 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.

--build=BUILD

   configure for building on BUILD, usually guessed by
   **config.guess**.

--host=HOST

   cross-compile to build programs to run on HOST (target platform)

--with-build-python=path/to/python

   path to build "python" binary for cross compiling

   Added in version 3.11.

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


3.4. Python Build System
========================


3.4.1. Main files of the build system
-------------------------------------

* "configure.ac" => "configure";

* "Makefile.pre.in" => "Makefile" (created by "configure");

* "pyconfig.h" (created by "configure");

* "Modules/Setup": C extensions built by the Makefile using
  "Module/makesetup" shell script;


3.4.2. 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 "Modules/Setup").


3.4.3. 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 "--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.


3.4.4. 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'

"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 "PyAPI_FUNC()", "PyAPI_DATA()" and "PyMODINIT_FUNC" macros of
"Include/exports.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 "ImportError" on import.


3.5. Compiler and linker flags
==============================

Options set by the "./configure" script and environment variables and
used by "Makefile".


3.5.1. Preprocessor flags
-------------------------

CONFIGURE_CPPFLAGS

   Value of "CPPFLAGS" variable passed to the "./configure" script.

   Added in version 3.6.

CPPFLAGS

   (Objective) C/C++ preprocessor flags, e.g. "-I*include_dir*" if you
   have headers in a nonstandard directory *include_dir*.

   Both "CPPFLAGS" and "LDFLAGS" need to contain the shell's value to
   be able to build extension modules using the directories specified
   in the environment variables.

BASECPPFLAGS

   Added in version 3.4.

PY_CPPFLAGS

   Extra preprocessor flags added for building the interpreter object
   files.

   Default: "$(BASECPPFLAGS) -I. -I$(srcdir)/Include
   $(CONFIGURE_CPPFLAGS) $(CPPFLAGS)".

   Added in version 3.2.


3.5.2. Compiler flags
---------------------

CC

   C compiler command.

   Example: "gcc -pthread".

CXX

   C++ compiler command.

   Example: "g++ -pthread".

CFLAGS

   C compiler flags.

CFLAGS_NODIST

   "CFLAGS_NODIST" is used for building the interpreter and stdlib C
   extensions.  Use it when a compiler flag should *not* be part of
   "CFLAGS" once Python is installed (gh-65320).

   In particular, "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 "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.

   Added in version 3.5.

COMPILEALL_OPTS

   Options passed to the "compileall" command line when building PYC
   files in "make install". Default: "-j0".

   Added in version 3.12.

EXTRA_CFLAGS

   Extra C compiler flags.

CONFIGURE_CFLAGS

   Value of "CFLAGS" variable passed to the "./configure" script.

   Added in version 3.2.

CONFIGURE_CFLAGS_NODIST

   Value of "CFLAGS_NODIST" variable passed to the "./configure"
   script.

   Added in version 3.5.

BASECFLAGS

   Base compiler flags.

OPT

   Optimization flags.

CFLAGS_ALIASING

   Strict or non-strict aliasing flags used to compile
   "Python/dtoa.c".

   Added in version 3.7.

CCSHARED

   Compiler flags used to build a shared library.

   For example, "-fPIC" is used on Linux and on BSD.

CFLAGSFORSHARED

   Extra C flags added for building the interpreter object files.

   Default: "$(CCSHARED)" when "--enable-shared" is used, or an empty
   string otherwise.

PY_CFLAGS

   Default: "$(BASECFLAGS) $(OPT) $(CONFIGURE_CFLAGS) $(CFLAGS)
   $(EXTRA_CFLAGS)".

PY_CFLAGS_NODIST

   Default: "$(CONFIGURE_CFLAGS_NODIST) $(CFLAGS_NODIST)
   -I$(srcdir)/Include/internal".

   Added in version 3.5.

PY_STDMODULE_CFLAGS

   C flags used for building the interpreter object files.

   Default: "$(PY_CFLAGS) $(PY_CFLAGS_NODIST) $(PY_CPPFLAGS)
   $(CFLAGSFORSHARED)".

   Added in version 3.7.

PY_CORE_CFLAGS

   Default: "$(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE".

   Added in version 3.2.

PY_BUILTIN_MODULE_CFLAGS

   Compiler flags to build a standard library extension module as a
   built-in module, like the "posix" module.

   Default: "$(PY_STDMODULE_CFLAGS) -DPy_BUILD_CORE_BUILTIN".

   Added in version 3.8.

PURIFY

   Purify command. Purify is a memory debugger program.

   Default: empty string (not used).


3.5.3. Linker flags
-------------------

LINKCC

   Linker command used to build programs like "python" and
   "_testembed".

   Default: "$(PURIFY) $(CC)".

CONFIGURE_LDFLAGS

   Value of "LDFLAGS" variable passed to the "./configure" script.

   Avoid assigning "CFLAGS", "LDFLAGS", etc. so users can use them on
   the command line to append to these values without stomping the
   pre-set values.

   Added in version 3.2.

LDFLAGS_NODIST

   "LDFLAGS_NODIST" is used in the same manner as "CFLAGS_NODIST".
   Use it when a linker flag should *not* be part of "LDFLAGS" once
   Python is installed (gh-65320).

   In particular, "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 "LDFLAGS" would take precedence over user- and
     package-supplied "-L" flags.

CONFIGURE_LDFLAGS_NODIST

   Value of "LDFLAGS_NODIST" variable passed to the "./configure"
   script.

   Added in version 3.8.

LDFLAGS

   Linker flags, e.g. "-L*lib_dir*" if you have libraries in a
   nonstandard directory *lib_dir*.

   Both "CPPFLAGS" and "LDFLAGS" need to contain the shell's value to
   be able to build extension modules using the directories specified
   in the environment variables.

LIBS

   Linker flags to pass libraries to the linker when linking the
   Python executable.

   Example: "-lrt".

LDSHARED

   Command to build a shared library.

   Default: "@LDSHARED@ $(PY_LDFLAGS)".

BLDSHARED

   Command to build "libpython" shared library.

   Default: "@BLDSHARED@ $(PY_CORE_LDFLAGS)".

PY_LDFLAGS

   Default: "$(CONFIGURE_LDFLAGS) $(LDFLAGS)".

PY_LDFLAGS_NODIST

   Default: "$(CONFIGURE_LDFLAGS_NODIST) $(LDFLAGS_NODIST)".

   Added in version 3.8.

PY_CORE_LDFLAGS

   Linker flags used for building the interpreter object files.

   Added in version 3.8.
