Boost logo

Boost-Build :

Subject: [Boost-build] Python build fails with 1.64.RC1 on Windows
From: Sophonet (boost_at_[hidden])
Date: 2017-03-28 11:38:53

Hi list,

a few months ago, I have reported a bug in boost build which was
introduced between 1.61 and 1.62 and screwed up python building when
using user-config.jam - specific python versions (order of python
versions was not recognized anymore, and only the first python
configuration in user-config.jam was picked for building). See here:

In boost 1.63, probably to a related issue, an additional problem
occurred even when the correct python version was the first entry in
user-config.jam. In that case, the installation could not find the
boost3 numpy library when installing (which indeed did not exist). I
have heard from other people that building boost 1.63 with numpy would
work if user-config.jam does not exist (which I have not checked

After 1.63 release, I have noticed some changes in the boost-python
specific build chain (related to However, when trying
1.64.RC1, boost python does actually not build at all anymore (I am
using python 3.6), even if user-config.jam is deleted and even if
explicitly saying --with-python.

There are two things.

1. When building b2, an error message appears:

'powershell' is not recognized as an internal or external command,
operable program or batch file.

...but building continues


   a) user-config.jam is not present: There is no activity at all to
build boost python, and even installation just stays silent and does
nothing without any error message.

   b) user-config.jam is present, and even if the first python entry
matches the correct version (3.6 in my case), nothing happens, but a few
more lines appear on the screen:

     - hardlinks supported : yes (cached)
error: No best alternative for libs/python/build/boost_python3
     next alternative: required properties: <python>3.6
     next alternative: required properties: <python>3.6
...found 1 target...
...updating 1 target...

I hope that it would be easy to fix these problems before the final 1.64
release - since the first problems occured, as mentioned above, already
in 1.62, which is more than half a year ago.

If there are any hints where I can help, please post to this list -
unfortunately, I am not that experienced in boost build's jam.

Thanks a lot,


Boost-Build list run by bdawes at, david.abrahams at, gregod at, cpdaniel at, john at