Building Boost with both Python 2 and 3 libraries on Windows 10

[AndroXD]

I'm on Windows 10 x64, I already unpacked "boost_1_69_0.7z" and ran "bootstrap.bat", however, when I compile it with "b2 toolset=msvc-14.16 --build-type=complete --abbreviate-paths architecture=x86 address-model=64 install -j4 --with-python python=2.7 --with-python python=3.6" I get this error message: "error: legal values: "3.6"". How do I compile more Python libraries? In case that's not possible, how do I choose which Python version I want to use? In case I cannot choose anything else than "3.6" then why that command line option exists at all if there's no choice? Thanks, I hope a solution exists.

[swatanabe]

AMDG

On 5/18/19 11:08 PM, AndroXD wrote:

I'm on Windows 10 x64, I already unpacked "boost_1_69_0.7z" and ran "bootstrap.bat", however, when I compile it with "b2 toolset=msvc-14.16 --build-type=complete --abbreviate-paths architecture=x86 address-model=64 install -j4 --with-python python=2.7 --with-python python=3.6" I get this error message: "error: legal values: "3.6"". How do I compile more Python libraries? In case that's not possible, how do I choose which Python version I want to use? In case I cannot choose anything else than "3.6" then why that command line option exists at all if there's no choice? Thanks, I hope a solution exists.

You need to configure both versions in project-config.jam (or user-config.jam). The default setup for python only finds a single version.

In Christ, Steven Watanabe

[cspanier]

I have the same issue with Boost 1.73 and tracked down the problem to a bug in src/tools/python.jam, where local rule configure prematurely selects a Python interpreter without checking for an explicitly selected version (using "python=X.Y" command line argument).

Context: Windows 10 x64 Python2.7 installed in C:\Python27 Python3.8 installed in C;\Python38 The PATH environment variable first lists Python 3.8, then 2.7: PATH=(...);C:\Python38\Scripts\;C:\Python38\;C:\Python27\Scripts\;C:\Python27\;(...)

A user-config.jam in Boost's root folder (no other user-config in any other folder on my system) containing:

using python : 2.7 : C:/Python27 ;
using python : 3.8 : C:/Python38 ;

I'm calling Boost build using the following arguments:

./b2
	--debug-configuration
	--layout=versioned
	--build-type=complete
	--without-mpi
	--without-graph_parallel
	python=2.7
	toolset=msvc-14.2
	architecture=x86
	address-model=64
	binary-format=pe
	threading=multi
	link=static,shared
	define=BOOST_USE_WINAPI_VERSION=0x0A00
	-sZLIB_INCLUDE=C:\\3rdparty\\x86_64-windows-vc142/include
	-sZLIB_LIBPATH=C:\\3rdparty\\x86_64-windows-vc142/lib
	-sBZIP2_INCLUDE=C:\\3rdparty\\x86_64-windows-vc142/include
	-sBZIP2_LIBPATH=C:\\3rdparty\\x86_64-windows-vc142/lib
	-sICU_PATH=C:\\3rdparty\\x86_64-windows-vc142
	--prefix=C:\\3rdparty\\x86_64-windows-vc142
	install
	-j32

The (relevant) output I get is this:

...
notice: [python-cfg] Configuring python...
notice: [python-cfg] Registry indicates Python 2.7 installed at "C:\Python27\"
notice: [python-cfg] Checking interpreter command "python"...
notice: [python-cfg] running command 'DIR /-C /A:S "C:\Python38\python.exe" 2>&1'
notice: [python-cfg] running command 'python -c "from sys import *; print('version=%d.%d\nplatform=%s\nprefix=%s\nexec_prefix=%s\nexecutable=%s' % (version_info[0],version_info[1],platform,prefix,exec_prefix,executable))" 2>&1'
notice: [python-cfg] ...requested configuration matched!
notice: [python-cfg] Details of this Python configuration:
notice: [python-cfg]   interpreter command: "python"
notice: [python-cfg]   include path: "C:\Python38\Include"
notice: [python-cfg]   library path: "C:\Python38\libs"
notice: [python-cfg]   DLL search path: "C:\Python38"
notice: [python-cfg] Checking for NumPy...
notice: [python-cfg] running command 'python -c "import sys; sys.stderr = sys.stdout; import numpy; print(numpy.get_include())"'
notice: [python-cfg] NumPy disabled. Reason:
notice: [python-cfg]   python -c "import sys; sys.stderr = sys.stdout; import numpy; print(numpy.get_include())" aborted with
notice: [python-cfg]   Traceback (most recent call last):
  File "<string>", line 1, in <module>
ModuleNotFoundError: No module named 'numpy'
C:/3rdparty/packages/boost_1_73_0_orig/tools/build/src/build\feature.jam:491: in feature.validate-value-string from module feature
error: "2.7" is not a known value of feature <python>
error: legal values: "3.8"

Adding a few extra lines debug output in src/tools/python.jam I noticed that on line 724 cmds-to-try = [ candidate-interpreters $(version) : $(prefix) : $(target-os) ] ; gets assigned python C:\Python38\python C:\Python27\python. This list is tested one by one on line 763 until the first command is accepted. This test seem to ignore my command line argument python=2.7, so the first Python interpreter on Path (which happens to be the 3.8 one) is selected. Later an error is thrown stating "2.7" is not a known value and only "3.8" is accepted.

I've added an extra test on line 785 to only accept selected Python versions (if one is explicitly selected) like so:

-                if $(cmd)
+                requested-version = [ MATCH python=(.*) : [ modules.peek : ARGV ] ] ;
+                if $(cmd) && ( ! ( $(requested-version) ) || ( $(sys.version) = $(requested-version) ) )

and now it is working as expected and as described in the documentation:

...
notice: [python-cfg] Configuring python...
notice: [python-cfg] Registry indicates Python 2.7 installed at "C:\Python27\"
notice: [python-cfg] Checking interpreter command "python"...
notice: [python-cfg] running command 'DIR /-C /A:S "C:\Python38\python.exe" 2>&1'
notice: [python-cfg] running command 'python -c "from sys import *; print('version=%d.%d\nplatform=%s\nprefix=%s\nexec_prefix=%s\nexecutable=%s' % (version_info[0],version_info[1],platform,prefix,exec_prefix,executable))" 2>&1'
notice: [python-cfg] Checking interpreter command "C:\Python27\python"...
notice: [python-cfg] running command 'DIR /-C /A:S "C:\Python27\python.exe" 2>&1'
notice: [python-cfg] running command 'C:\Python27\python -c "from sys import *; print('version=%d.%d\nplatform=%s\nprefix=%s\nexec_prefix=%s\nexecutable=%s' % (version_info[0],version_info[1],platform,prefix,exec_prefix,executable))" 2>&1'
notice: [python-cfg] ...requested configuration matched!
notice: [python-cfg] Details of this Python configuration:
notice: [python-cfg]   interpreter command: "C:\Python27\python"
notice: [python-cfg]   include path: "C:\Python27\Include"
notice: [python-cfg]   library path: "C:\Python27\libs"
notice: [python-cfg]   DLL search path: "C:\Python27"
notice: [python-cfg] Checking for NumPy...
notice: [python-cfg] running command 'C:\Python27\python -c "import sys; sys.stderr = sys.stdout; import numpy; print(numpy.get_include())"'
notice: [python-cfg] NumPy disabled. Reason:
notice: [python-cfg]   C:\Python27\python -c "import sys; sys.stderr = sys.stdout; import numpy; print(numpy.get_include())" aborted with
notice: [python-cfg]   Traceback (most recent call last):
  File "<string>", line 1, in <module>
ImportError: No module named numpy
Performing configuration checks

    - default address-model    : 32-bit
    - default architecture     : x86
...

Am I missing something or is this indeed a bug?

[cspanier]

Another note: src/tools/python.jam line 396 builds a list of versions to search for in Windows registry:

# Build a list of versions from 3.4 down to 1.5. Because bjam can not enumerate
# registry sub-keys, we have no way of finding a version with a 2-digit minor
# version, e.g. 2.10 -- let us hope that never happens.
#
.version-countdown = ;
for local v in [ numbers.range 15 34 ]
{
    .version-countdown = [ SUBST $(v) (.)(.*) $1.$2 ] $(.version-countdown) ;
}

This code hasn't been updated in a while, because meanwhile we've reached Python 3.8. Changing the upper bound from 34 to 38 (or 39) successfully finds the 3.8 interpreter, but didn't solve the error described above.

notice: [python-cfg] Registry indicates Python 3.8 installed at "C:\Python38\"
notice: [python-cfg] Registry indicates Python 2.7 installed at "C:\Python27\"

Nevertheless, this loop should also be updated.

[stale[bot]]

Thank you for your contributions. Main development of B2 has moved to https://github.com/bfgroup/b2 This issue has been automatically marked as "transition" to indicate the potential for needing transition to the new B2 development project.