Travis: generalize matrix to cover python versions as well as gcc versions

[davidmalcolm]

Ideally we'd test for the matrix of all supported gcc versions vs all supported Python versions.

(Help with this would be appreciated!)

[vries]

I've looked into this, and got as far as #147.

I managed to specify a 2 by 2 matrix using dimensions env and python:

os:
- linux

addons:
  apt:
    sources:
      - ubuntu-toolchain-r-test
    packages:
      - g++-4.8 gcc-4.8-plugin-dev g++-8 gcc-8-plugin-dev

env:
  - MATRIX_EVAL="CC=gcc-4.8 && CXX=g++-4.8"
  - MATRIX_EVAL="CC=gcc-8 && CXX=g++-8"

language: python
python:
  - "2.7"
  - "3.6"

before_install:
  - eval "${MATRIX_EVAL}"

install:
  - pip install six pygments graphviz lxml

script: make CC=$CC CXX=$CXX

So, there are 4 builds, and I run into two errors:

• 4.8/8 and 2.7: Runs into "ImportError: cannot import name _remove_dead_weakref"
• 4.8/8 and 3.6: Runs into "/usr/bin/ld: cannot find -lpython3.6m" when linking python.so

Both seem be problems with the virtualenv that is setup for python, but I don't know how to fix these.

[vries]

So, there are 4 builds, and I run into two errors:

* 4.8/8 and 2.7: Runs into "ImportError: cannot import name _remove_dead_weakref"

* 4.8/8 and 3.6: Runs into "/usr/bin/ld: cannot find -lpython3.6m" when linking python.so

Both seem be problems with the virtualenv that is setup for python, but I don't know how to fix these.

I think I managed to fix/workaround this.

On my opensuse leap laptop, we have:

$ python-config --ldflags
-lpython2.7 -lpthread -ldl -lutil -lm -Xlinker -export-dynamic
$ python2-config --ldflags
-lpython2.7 -lpthread -ldl -lutil -lm -Xlinker -export-dynamic
$ python3-config --ldflags
 -L/usr/lib64 -lpython3.6m -lpthread -ldl  -lutil -lm  -Xlinker -export-dynamic

but if I start up an virtualenv with python3, I get:

$ virtualenv -p python3 tmp
Already using interpreter /usr/bin/python3
Using base prefix '/usr'
New python executable in /home/vries/tmp/bin/python3
Also creating executable in /home/vries/tmp/bin/python
Installing setuptools, pip, wheel...done.
$ . ./tmp/bin/activate
(tmp) $ python-config --ldflags
-lpython3.6m -lpthread -ldl -lutil -lm -Xlinker -export-dynamic

So, it seems the virtualenv drops the " -L/usr/lib64" for some reason.

The patch below adds it back, and allows us have a reasonable testrun:

diff --git a/Makefile b/Makefile
index daa7419..d83404a 100644
--- a/Makefile
+++ b/Makefile
@@ -98,7 +98,8 @@ PYTHON_CONFIG=python-config
 #PYTHON_CONFIG=python3.3dm-config
 
 PYTHON_INCLUDES=$(shell $(PYTHON_CONFIG) --includes)
-PYTHON_LIBS=$(shell $(PYTHON_CONFIG) --libs)
+PYTHON_LIBPL=$(shell $(PYTHON) -c "import sysconfig; print(sysconfig.get_config_var('LIBPL'))")
+PYTHON_LIBS=$(shell $(PYTHON_CONFIG) --ldflags; $(PYTHON_CONFIG) --libs; echo "-L$(PYTHON_LIBPL)"; )
 
 # Support having multiple named plugins
 # e.g. "python2.7" "python3.2mu" "python 3.2dmu" etc:

[vries]

@davidmalcolm

Please take a look at:

• https://travis-ci.com/vries/gcc-python-plugin/builds/86787194
• https://github.com/vries/gcc-python-plugin/tree/travis-yml-python-v12

Can you take it from here?

Thanks,
Tom