Bug 2863

Mathias, I tried './waf configure' on a Python 3.6.3 (Ubuntu 17.10) system and the existing code works for me.  Can you provide more info about how it is breaking for you?

Sure,

The issue occurs when pygccxml is installed (not sure if pybindgen is needed to reproduce the bug).

The following stacktrace occurs then:

$ ./waf configure -d debug --enable-examples --enable-tests
Setting top to                           : /home/mettinger/SNS3/ns-3-dev-git 
Setting out to                           : /home/mettinger/SNS3/ns-3-dev-git/build 
Checking for 'gcc' (C compiler)          : /usr/bin/gcc 
Checking for cc version                  : 7.2.1 
Checking for 'g++' (C++ compiler)        : /usr/bin/g++ 
Checking for compilation flag -Wl,--soname=foo support : ok 
Checking for compilation flag -std=c++11 support       : ok 
Checking for program 'python'                          : /usr/bin/python 
Checking for python version                            : (3, 6, 4, 'final', 0) 
python-config                                          : /usr/bin/python-config 
Asking python-config for pyembed '--cflags --libs --ldflags' flags : yes 
Testing pyembed configuration                                      : yes 
Asking python-config for pyext '--cflags --libs --ldflags' flags   : yes 
Testing pyext configuration                                        : yes 
Checking for compilation flag -fvisibility=hidden support          : ok 
Checking for compilation flag -Wno-array-bounds support            : ok 
Checking for pybindgen location                                    : not found 
Checking for python module 'pybindgen'                             : 0.18.0 
Checking for pybindgen version                                     : 0.18.0 
Checking for code snippet                                          : yes 
Checking for types uint64_t and unsigned long equivalence          : no 
Checking for code snippet                                          : no 
Checking for types uint64_t and unsigned long long equivalence     : yes 
Checking for the apidefs that can be used for Python bindings      : gcc-LP64 
Checking for internal GCC cxxabi                                   : complete 
Checking for python module 'pygccxml'                              : 1.9.1 
  File "<string>", line 1
    import pygccxml; print pygccxml.__version__
                                  ^
SyntaxError: invalid syntax
Traceback (most recent call last):
  File "/home/mettinger/SNS3/ns-3-dev-git/.waf3-1.8.19-b1fc8f7baef51bd2db4c2971909a568d/waflib/Scripting.py", line 110, in waf_entry_point
    run_commands()
  File "/home/mettinger/SNS3/ns-3-dev-git/.waf3-1.8.19-b1fc8f7baef51bd2db4c2971909a568d/waflib/Scripting.py", line 171, in run_commands
    ctx=run_command(cmd_name)
  File "/home/mettinger/SNS3/ns-3-dev-git/.waf3-1.8.19-b1fc8f7baef51bd2db4c2971909a568d/waflib/Scripting.py", line 162, in run_command
    ctx.execute()
  File "/home/mettinger/SNS3/ns-3-dev-git/.waf3-1.8.19-b1fc8f7baef51bd2db4c2971909a568d/waflib/Configure.py", line 87, in execute
    super(ConfigurationContext,self).execute()
  File "/home/mettinger/SNS3/ns-3-dev-git/.waf3-1.8.19-b1fc8f7baef51bd2db4c2971909a568d/waflib/Context.py", line 93, in execute
    self.recurse([os.path.dirname(g_module.root_path)])
  File "/home/mettinger/SNS3/ns-3-dev-git/.waf3-1.8.19-b1fc8f7baef51bd2db4c2971909a568d/waflib/Context.py", line 134, in recurse
    user_function(self)
  File "/home/mettinger/SNS3/ns-3-dev-git/wscript", line 464, in configure
    conf.recurse('bindings/python')
  File "/home/mettinger/SNS3/ns-3-dev-git/.waf3-1.8.19-b1fc8f7baef51bd2db4c2971909a568d/waflib/Context.py", line 134, in recurse
    user_function(self)
  File "/home/mettinger/SNS3/ns-3-dev-git/bindings/python/wscript", line 281, in configure
    pygccxml_version_str = pygccxml_version_str.lstrip('v')
TypeError: a bytes-like object is required, not 'str'

To comment further on, the issue is twofold:

 1. The -c argument to the python invokation is not a valid Python 3 program (print keyword vs. print function); and
 2. The returned value of subprocess.Popen.communicate is a couple of bytes object in Python 3.

I chose to "import pygccxml" rather than fixing the subprocess call as it seems to me that there is no benefit in using subprocess here. But I don't know the rationale of using subprocess at all in the first place so I may be wrong. An other way to fix it would be to make more like the pybindgen check (lines 192 to 196) by:

 1. Using the print function for the -c argument of the python call (which would make no difference when using Python 2); and
 2. Using maybe_decode on the stdout stream of the subprocess call.

Either way, whatever the solution chosen is, it should be a good idea to have the pybindgen and pygccxml checks match for easier maintenance.

fixed in 13391:8548005c28b1