Build is incompatible with SCons 3 / Python 3

[Uwe Klotz]

After upgrading to Fedora 27 and SCons 3.0.0 the build aborts immediately with the following error:

scons: Reading SConscript files ...
ModuleNotFoundError: No module named 'util':
  File "/home/uk/Projects/Mixxx/mixxx/SConstruct", line 29:
    from build import mixxx, features, depends
  File "/home/uk/Projects/Mixxx/mixxx/build/mixxx.py", line 15:
    import util

Real blocker, I'm currently not able to build Mixxx. Any ideas?

[Daniel Schürmann (daschuer)]

https://stackoverflow.com/questions/12172791/changes-in-import-statement-python3

does
from . import util
helps?

[Sean M. Pappalardo (pegasus-renegadetech)]

What happens if you remove/comment out the 'import util' line in mixxx.py?

[Uwe Klotz (uklotzde-deactivatedaccount)]

Thanks, imports fixed:

from .<optional-subfolder> import <package>

But now the next blocker appeared:

ERROR:root:Couldn't determine platform. os.name: posix sys.platform: linux
Exception: invalid target platform:
  File "/home/uk/Projects/Mixxx/mixxx/SConstruct", line 72:
    toolchain, available_features)
  File "/home/uk/Projects/Mixxx/mixxx/build/mixxx.py", line 46:
    raise Exception("invalid target platform")

[Uwe Klotz (uklotzde-deactivatedaccount)]

Next one fixed. But there are still print errors:

  File "/home/uk/Projects/Mixxx/mixxx/build/qt4.py", line 192

    print "scons: qt4: Scanning '%s' (header of '%s')" % (str(h), str(cpp))

SyntaxError: invalid syntax

[Sean M. Pappalardo (pegasus-renegadetech)]

Critical is for _application_ show-stopper bugs (i.e. crashes in the middle of a set doing normal things.)

[Uwe Klotz (uklotzde-deactivatedaccount)]

...many legacy print statements :(

[Be (be.ing)]

If the application can't build at all, nothing about the application matters, therefore this is critical.

[Daniel Schürmann (daschuer)]

This should be already fixed in master:
https://github.com/mixxxdj/mixxx/pull/1361

[Uwe Klotz (uklotzde-deactivatedaccount)]

https://github.com/mixxxdj/mixxx/pull/1381

Giving up now.

[Uwe Klotz (uklotzde-deactivatedaccount)]

TODO: build/osx/OSConsX.py still contains many legacy print statements as a simple grep reveals.

[Sébastien BLAISOT (sblaisot)]

@Be I disagree. we curently have everything we need to build the application with scons 2.x on CI and build server.

so this is not critical project-wide. This is only critical for developpers that updated to a bleeding-edge scons 3.

mixxx build prerequisites are stuck to scons 2.x.

it is important to fix mixxx build to work with scons 3 but this is not a release blocker.

[Conner Phillips (lindybalboa)]

@uklotzde, despite the print statements being fixed to be python3 compatible, the scons binary still needs to be called using python2 because of the util module. I agree it is a messed up situation and all of the python files need a close inspection to get them up to python3 standards.

In the mean time, with python3 as my environmental python, I can succesfully use this code to compile mixxx:

python2 /usr/bin/scons ...+ whatever flags you choose

[Uwe Klotz (uklotzde-deactivatedaccount)]

Will not be fixed for Mixxx 2.1.

A temporary workaround is documented in the Wiki:
https://mixxx.org/wiki/doku.php/compiling_on_linux

[bdbaddog (bill-baddogconsulting)]

SCons 3.0.1 fixed the issue with requiring python3 style print statements when running scons with python 2.7.x.

Are there other issues?

[RJ Skerry-Ryan (rryan)]

works fine on osx now
https://github.com/mixxxdj/mixxx/commit/73d02e58bcd55ac4e0c3ce6047b28057629ddd7e

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/8973