[Scons-users] Determining source of scons crash

[Bill Deegan]

Can you repro with a small example?
--taskmastertrace=trace.log can provide some useful information.

You could wrap the line 624 in a try except and have it pop into the
debugger in the except.

On Fri, Apr 24, 2020 at 9:31 AM Luke Robison <lukerobison at gmail.com> wrote:

> I'm trying to track down a crash I have triggered in scons (both 3.0.1 and
> 3.1.2).  This crash only happens when I ask scons to build my entire output
> directory (it will happily compile if my command-line target is
> build-variant/my_prog.exe, but giving it the target build-variant causes
> the crash).
>
> AttributeError: 'NoneType' object has no attribute 'get_build_env':
>   File "/usr/lib/scons/SCons/Script/Main.py", line 1376:
>     _exec_main(parser, values)
>   File "/usr/lib/scons/SCons/Script/Main.py", line 1339:
>     _main(parser)
>   File "/usr/lib/scons/SCons/Script/Main.py", line 1103:
>     nodes = _build_targets(fs, options, targets, target_top)
>   File "/usr/lib/scons/SCons/Script/Main.py", line 1313:
>     jobs.run(postfunc = jobs_postfunc)
>   File "/usr/lib/scons/SCons/Job.py", line 111:
>     self.job.start()
>   File "/usr/lib/scons/SCons/Job.py", line 229:
>     task.executed()
>   File "/usr/lib/scons/SCons/Script/Main.py", line 237:
>     SCons.Taskmaster.OutOfDateTask.executed(self)
>   File "/usr/lib/scons/SCons/Taskmaster.py", line 312:
>     t.push_to_cache()
>   File "/usr/lib/scons/SCons/Node/FS.py", line 2910:
>     self.get_build_env().get_CacheDir().push(self)
>   File "/usr/lib/scons/SCons/Node/__init__.py", line 624:
>     result = self.get_executor().get_build_env()
>
> I have two questions:
> 1) How can I go about debugging this?  I found --debug=pdb to be usless
> here, as I end up in Main.py calling _build_targets rather than where the
> error occurs.  Similarly, I can't do --tree, since python crashes before it
> gets to that point.  Modifying the scons source with print statements has
> been my way forward for now.
> 2) Is it considered a bug to have scons crash like this (even if I may
> have fed it something bad?)
>
> After adding some prints to the scons code, It seems one of my compiled
> header outputs (code is Fortran, so the compiled header is foo.mod) is the
> "self" here, and self.get_executor() returns "None", and then python fails
> on trying to call None.get_build_env().  This crash happens immediately
> after building the relevant SharedObject file (foo.os) from the source
> (foo.f90).  It doesn't happen for all files, but it happens predictably on
> some, and those tend to have no dependencies themselves. Re-running the
> build enough times will eventually let it complete.
>
> Any suggestions greatly appreciated.
>
> Luke
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