Pants bundling with wrong version of Python?

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Grant Wu

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Jun 9, 2015, 7:43:15 PM6/9/15

to pants...@googlegroups.com

Hello!

Grant here. Member of a team of avid Pants-wearers. Running into an issue for which I've failed to find a solution.

I have Python code that uses 'raise...from' syntax as outlined here. And here is a Gist containing some test code I'm trying to run.

A file named "test.py" containing only the contents of the above Gist fails to run / bundle with Pants. Error:

"Exception message: invalid syntax (test.py, line 4)"

The same test.py runs successfully when invoked with Python3.4.3, and gives the expected syntax error with Python2.

Here is my pants.ini. I'm specifying "interpreter_requirement: CPython>=3.4,<3.5".

I'm specifying a version of Python that should support 'raise...from', so I can't figure out why Pants is giving me a syntax error. I'm wondering if there's something else I need to do to tell Pants which version of Python I'm using.

Am I missing something? Thanks so much in advance for your help.

Best,

Grant Wu

John Sirois

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Jun 9, 2015, 8:11:22 PM6/9/15

to Grant Wu, pants-devel

Nope - this is a bug.

I did a minimal repo like so:

1.) Setup a pants python repo:

===

jsirois@gill ~ $ mkdir /tmp/test

jsirois@gill ~ $ cd /tmp/test

jsirois@gill /tmp/test $ virtualenv -p python2 build-support/pants.venv

...

jsirois@gill /tmp/test $ source build-support/pants.venv/bin/activate

(pants.venv)jsirois@gill /tmp/test $ pip install pantsbuild.pants

...

(pants.venv)jsirois@gill /tmp/test $ cat << EOF > pants.ini

> [python-setup]

> interpreter_requirement: CPython>=3.4,<3.5

> EOF

2.) Setup your case:

===

(pants.venv)jsirois@gill /tmp/test $ cat << EOF > main.py

> try:

> print(1 / 0)

> except Exception as exc:

> raise RuntimeError("Something bad happened") from exc

> EOF

(pants.venv)jsirois@gill /tmp/test $ cat << EOF > BUILD

> python_binary(

> name='main',

> source='main.py'

> )

> EOF

3.) Repro the run ... not quite so fast

===

(pants.venv)jsirois@gill /tmp/test $ pants run :main

...

17:50:25 00:00 [resolve]

17:50:25 00:00 [ivy]

Failed to resolve target for tool: //:nailgun-server.

This target was obtained from option nailgun-server in scope resolve.ivy.

You probably need to add this target to your tools BUILD file(s), usually located in the workspace root.

FAILURE

...

URG - tracked here: https://github.com/pantsbuild/pants/issues/940

4.) Add the nailgun tool dep:

===

(pants.venv)^jsirois@gill /tmp/test $ cat << EOF > BUILD.tools

> jar_library(

> name='nailgun-server',

> jars=[

> jar('com.martiansoftware', 'nailgun-server', '0.9.1')

> ]

> )

> EOF

5.) Really do the repro:

===

(pants.venv)jsirois@gill /tmp/test $ pants binary :main --print-exception-stacktrace

...

17:52:22 00:00 [binary]

17:52:22 00:00 [python-binary-create]

Detected interpreter /home/jsirois/.pyenv/versions/3.4.2/bin/python3.4: CPython-3.4.2

Detected interpreter /usr/bin/python3.4: CPython-3.4.3fatal: Not a git repository (or any parent up to mount point /tmp)

Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set).

17:52:23 00:01 [chroot]

FAILURE

Exception caught:

File "/tmp/test/build-support/pants.venv/bin/pants", line 9, in <module>

load_entry_point('pantsbuild.pants==0.0.32', 'console_scripts', 'pants')()

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/bin/pants_exe.py", line 81, in main

_run(exiter)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/bin/pants_exe.py", line 74, in _run

result = goal_runner.run()

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/bin/goal_runner.py", line 174, in run

result = self._do_run()

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/bin/goal_runner.py", line 230, in _do_run

return engine.execute(context, self.goals)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/engine/engine.py", line 26, in execute

self.attempt(context, goals)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/engine/round_engine.py", line 212, in attempt

goal_executor.attempt(explain)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/engine/round_engine.py", line 45, in attempt

task.execute()

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/backend/python/tasks/python_binary_create.py", line 38, in execute

self.create_binary(binary)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/backend/python/tasks/python_binary_create.py", line 51, in create_binary

with self.temporary_chroot(interpreter=interpreter, pex_info=pexinfo, targets=[binary], platforms=binary.platforms) as chroot:

File "/usr/lib64/python2.7/contextlib.py", line 17, in __enter__

return self.gen.next()

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/backend/python/tasks/python_task.py", line 104, in temporary_chroot

chroot.dump()

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/backend/python/python_chroot.py", line 178, in dump

self._dump_library(lib)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/backend/python/python_chroot.py", line 112, in _dump_library

copy_to_chroot(library.target_base, relpath, self._builder.add_source)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pants/backend/python/python_chroot.py", line 107, in copy_to_chroot

add_function(src, path)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pex/pex_builder.py", line 136, in add_source

pyc_object = CodeMarshaller.from_py(fp.read(), env_filename)

File "/tmp/test/build-support/pants.venv/lib/python2.7/site-packages/pex/marshaller.py", line 70, in from_py

code = compile(py.replace('\r\n', '\n').replace('\r', '\n'), filename, 'exec')

Exception message: invalid syntax (main.py, line 4)

I've filed all this here for more investigation: https://github.com/pantsbuild/pants/issues/1658