cpython/PCbuild

Quick Start Guide

-----------------



1.  Install Microsoft Visual Studio 2015, any edition.

2.  Install Subversion, and make sure 'svn.exe' is on your PATH.

3.  Run "build.bat -e" to build Python in 32-bit Release configuration.

4.  (Optional, but recommended) Run the test suite with "rt.bat -q".





Building Python using Microsoft Visual C++

------------------------------------------



This directory is used to build CPython for Microsoft Windows NT version

6.0 or higher (Windows Vista, Windows Server 2008, or later) on 32 and 64

bit platforms.  Using this directory requires an installation of

Microsoft Visual C++ 2015 (MSVC 14.0) of any edition.  The specific

requirements are as follows:



Visual Studio Express 2015 for Desktop

Visual Studio Professional 2015

    Either edition is sufficient for building all configurations except

    for Profile Guided Optimization.

    The Python build solution pcbuild.sln makes use of Solution Folders,

    which this edition does not support.  Any time pcbuild.sln is opened

    or reloaded by Visual Studio, a warning about Solution Folders will

    be displayed, which can be safely dismissed with no impact on your

    ability to build Python.

    Required for building 64-bit Debug and Release configuration builds

Visual Studio Premium 2015

    Required for building Release configuration builds that make use of

    Profile Guided Optimization (PGO), on either platform.



All you need to do to build is open the solution "pcbuild.sln" in Visual

Studio, select the desired combination of configuration and platform,

then build with "Build Solution".  You can also build from the command

line using the "build.bat" script in this directory; see below for

details.  The solution is configured to build the projects in the correct

order.



The solution currently supports two platforms.  The Win32 platform is

used to build standard x86-compatible 32-bit binaries, output into the

win32 sub-directory.  The x64 platform is used for building 64-bit AMD64

(aka x86_64 or EM64T) binaries, output into the amd64 sub-directory.

The Itanium (IA-64) platform is no longer supported.  See the "Building

for AMD64" section below for more information about 64-bit builds.



Four configuration options are supported by the solution:

Debug

    Used to build Python with extra debugging capabilities, equivalent

    to using ./configure --with-pydebug on UNIX.  All binaries built

    using this configuration have "_d" added to their name:

    python35_d.dll, python_d.exe, parser_d.pyd, and so on.  Both the

    build and rt (run test) batch files in this directory accept a -d

    option for debug builds.  If you are building Python to help with

    development of CPython, you will most likely use this configuration.

PGInstrument, PGUpdate

    Used to build Python in Release configuration using PGO, which

    requires Premium Edition of Visual Studio.  See the "Profile

    Guided Optimization" section below for more information.  Build

    output from each of these configurations lands in its own

    sub-directory of this directory.  The official Python releases may

    be built using these configurations.

Release

    Used to build Python as it is meant to be used in production

    settings, though without PGO.





Building Python using the build.bat script

----------------------------------------------



In this directory you can find build.bat, a script designed to make

building Python on Windows simpler.  This script will use the env.bat

script to detect one of Visual Studio 2015, 2013, 2012, or 2010, any of

which may be used to build Python, though only Visual Studio 2015 is

officially supported.



By default, build.bat will build Python in Release configuration for

the 32-bit Win32 platform.  It accepts several arguments to change

this behavior:



   -c <configuration>  Set the configuration (see above)

   -d                  Shortcut for "-c Debug"

   -p <platform>       Set the platform to build for ("Win32" or "x64")

   -r                  Rebuild instead of just building

   -t <target>         Set the target (Build, Rebuild, Clean or CleanAll)

   -e                  Use get_externals.bat to fetch external sources

   -M                  Don't build in parallel

   -v                  Increased output messages



Up to 9 MSBuild switches can also be passed, though they must be passed

after specifying any of the above switches.  For example, use:



   build.bat -e -d /fl



to do a debug build with externals fetched as needed and write detailed

build logs to a file.  If the MSBuild switch requires an equal sign

("="), the entire switch must be quoted:



   build.bat -e -d "/p:ExternalsDir=P:\cpython-externals"



There may also be other situations where quotes are necessary.





C Runtime

---------



Visual Studio 2015 uses version 14 of the C runtime (MSVCRT14).  The

executables no longer use the "Side by Side" assemblies used in previous

versions of the compiler.  This simplifies distribution of applications.



The run time libraries are available under the VC/Redist folder of your

Visual Studio distribution. For more info, see the Readme in the

VC/Redist folder.





Sub-Projects

------------



The CPython project is split up into several smaller sub-projects which

are managed by the pcbuild.sln solution file.  Each sub-project is

represented by a .vcxproj and a .vcxproj.filters file starting with the

name of the sub-project.  These sub-projects fall into a few general

categories:



The following sub-projects represent the bare minimum required to build

a functioning CPython interpreter.  If nothing else builds but these,

you'll have a very limited but usable python.exe:

pythoncore

    .dll and .lib

python

    .exe

make_buildinfo, make_versioninfo

    helpers to provide necessary information to the build process



These sub-projects provide extra executables that are useful for running

CPython in different ways:

pythonw

    pythonw.exe, a variant of python.exe that doesn't open a Command

    Prompt window

pylauncher

    py.exe, the Python Launcher for Windows, see

        http://docs.python.org/3/using/windows.html#launcher

pywlauncher

    pyw.exe, a variant of py.exe that doesn't open a Command Prompt

    window

_testembed

    _testembed.exe, a small program that embeds Python for testing

    purposes, used by test_capi.py



These are miscellaneous sub-projects that don't really fit the other

categories:

_freeze_importlib

    _freeze_importlib.exe, used to regenerate Python\importlib.h after

    changes have been made to Lib\importlib\_bootstrap.py

bdist_wininst

    ..\Lib\distutils\command\wininst-14.0[-amd64].exe, the base

    executable used by the distutils bdist_wininst command

python3dll

    python3.dll, the PEP 384 Stable ABI dll

xxlimited

    builds an example module that makes use of the PEP 384 Stable ABI,

    see Modules\xxlimited.c



The following sub-projects are for individual modules of the standard

library which are implemented in C; each one builds a DLL (renamed to

.pyd) of the same name as the project:

_ctypes

_ctypes_test

_decimal

_elementtree

_hashlib

_msi

_multiprocessing

_overlapped

_socket

_testcapi

_testbuffer

_testimportmultiple

pyexpat

select

unicodedata

winsound



The following Python-controlled sub-projects wrap external projects.

Note that these external libraries are not necessary for a working

interpreter, but they do implement several major features.  See the

"Getting External Sources" section below for additional information

about getting the source for building these libraries.  The sub-projects

are:

_bz2

    Python wrapper for version 1.0.6 of the libbzip2 compression library

    Homepage:

        http://www.bzip.org/

_lzma

    Python wrapper for the liblzma compression library, using pre-built

    binaries of XZ Utils version 5.0.5

    Homepage:

        http://tukaani.org/xz/

_ssl

    Python wrapper for version 1.0.1j of the OpenSSL secure sockets

    library, which is built by ssl.vcxproj

    Homepage:

        http://www.openssl.org/



    Building OpenSSL requires nasm.exe (the Netwide Assembler), version

    2.10 or newer from

        http://www.nasm.us/

    to be somewhere on your PATH.  More recent versions of OpenSSL may

    need a later version of NASM. If OpenSSL's self tests don't pass,

    you should first try to update NASM and do a full rebuild of

    OpenSSL.  get_externals.py also downloads a snapshot of NASM, and the

    libeay and ssleay sub-projects use that version of nasm.exe.



    The libeay/ssleay sub-projects expect your OpenSSL sources to have

    already been configured and be ready to build.  If you get your sources

    from svn.python.org as suggested in the "Getting External Sources"

    section below, the OpenSSL source will already be ready to go.  If

    you want to build a different version, you will need to run



       PCbuild\prepare_ssl.py path\to\openssl-source-dir



    That script will prepare your OpenSSL sources in the same way that

    those available on svn.python.org have been prepared.  Note that

    Perl must be installed and available on your PATH to configure

    OpenSSL.  ActivePerl is recommended and is available from

        http://www.activestate.com/activeperl/



    The libeay and ssleay sub-projects will build the modules of OpenSSL

    required by _ssl and _hashlib and may need to be manually updated when

    upgrading to a newer version of OpenSSL or when adding new

    functionality to _ssl or _hashlib. They will not clean up their output

    with the normal Clean target; CleanAll should be used instead.

_sqlite3

    Wraps SQLite 3.8.3.1, which is itself built by sqlite3.vcxproj

    Homepage:

        http://www.sqlite.org/

_tkinter

    Wraps version 8.6.1 of the Tk windowing system.

    Homepage:

        http://www.tcl.tk/



    Tkinter's dependencies are built by the tcl.vcxproj and tk.vcxproj

    projects.  The tix.vcxproj project also builds the Tix extended

    widget set for use with Tkinter.



    Those three projects install their respective components in a

    directory alongside the source directories called "tcltk" on

    Win32 and "tcltk64" on x64.  They also copy the Tcl and Tk DLLs

    into the current output directory, which should ensure that Tkinter

    is able to load Tcl/Tk without having to change your PATH.



    The tcl, tk, and tix sub-projects do not clean their builds with

    the normal Clean target; if you need to rebuild, you should use the

    CleanAll target or manually delete their builds.





Getting External Sources

------------------------



The last category of sub-projects listed above wrap external projects

Python doesn't control, and as such a little more work is required in

order to download the relevant source files for each project before they

can be built.  However, a simple script is provided to make this as

painless as possible, called "get_externals.bat" and located in this

directory.  This script extracts all the external sub-projects from

    http://svn.python.org/projects/external

via Subversion (so you'll need svn.exe on your PATH) and places them

in ..\externals (relative to this directory).



It is also possible to download sources from each project's homepage,

though you may have to change folder names or pass the names to MSBuild

as the values of certain properties in order for the build solution to

find them.  This is an advanced topic and not necessarily fully

supported.





Building for AMD64

------------------



The build process for AMD64 / x64 is very similar to standard builds,

you just have to set x64 as platform. In addition, the HOST_PYTHON

environment variable must point to a Python interpreter (at least 2.4),

to support cross-compilation from Win32.





Profile Guided Optimization

---------------------------



The solution has two configurations for PGO. The PGInstrument

configuration must be built first. The PGInstrument binaries are linked

against a profiling library and contain extra debug information. The

PGUpdate configuration takes the profiling data and generates optimized

binaries.



The build_pgo.bat script automates the creation of optimized binaries.

It creates the PGI files, runs the unit test suite or PyBench with the

PGI python, and finally creates the optimized files.



See

    http://msdn.microsoft.com/en-us/library/e7k32f4k(VS.100).aspx

for more on this topic.





Static library

--------------



The solution has no configuration for static libraries. However it is

easy to build a static library instead of a DLL. You simply have to set

the "Configuration Type" to "Static Library (.lib)" and alter the

preprocessor macro "Py_ENABLE_SHARED" to "Py_NO_ENABLE_SHARED". You may

also have to change the "Runtime Library" from "Multi-threaded DLL

(/MD)" to "Multi-threaded (/MT)".





Visual Studio properties

------------------------



The PCbuild solution makes use of Visual Studio property files (*.props)

to simplify each project. The properties can be viewed in the Property

Manager (View -> Other Windows -> Property Manager) but should be

carefully modified by hand.



The property files used are:

 * python (versions, directories and build names)

 * pyproject (base settings for all projects)

 * openssl (used by libeay and ssleay projects)

 * tcltk (used by _tkinter, tcl, tk and tix projects)



The pyproject property file defines all of the build settings for each

project, with some projects overriding certain specific values. The GUI

doesn't always reflect the correct settings and may confuse the user

with false information, especially for settings that automatically adapt

for diffirent configurations.





Your Own Extension DLLs

-----------------------



If you want to create your own extension module DLL (.pyd), there's an

example with easy-to-follow instructions in ..\PC\example\; read the

file readme.txt there first.