More than One Compiler and Then The End

22 Aug 2015

At this point I have been able to configure Ubuntu 12.04 to compile my small C++11 library, I have also been able to configure Travis to automatically compile the library from the github source. Travis allows you to configure more than one compiler, which sounds fantastic from my perspective. Unfortunately, why they allow you to test your code against multiple versions of Python (ref) they do not (yet) allow you to easily configure multiple C++ compiler versions.

This is not too difficult in practice, you simply need to override the CXX and CC environment variable settings to your liking. In my case I modified the compiler section in the .travis.yml file to look like this:

compiler:
  - clang
  - gcc

Then I modified the before_script section to include:

before_script:
  - uname -a
....
..
  - if [ "x$CC" == "xgcc" ]; then CXX=g++-4.9; CC=gcc-4.9; fi
  - if [ "x$CC" == "xclang" ]; then CXX=clang++-3.6; CC=clang-3.6; fi
  - export CC
  - export CXX  

The full configuration file is here

Future Changes

The solution described above for testing multiple compilers is not very scalable. It seems the state of the art is to use the new container-based build infrastructure in Travis, and build a matrix of configurations as described here, or if you want an even more sophisticated example look at this one.

I will probably need such an approach when I start testing builds with code coverage, without it, with optimizations and without them, with different memory checking tools (ASAN, TSAN, etc). But for the time being I am satisfied that I can continue to code and have something running the tests for me.

Taking Stock

I started this series of posts to investigate if it was possible to setup C++11 builds using any of the hosted continuous integration solutions out there. Though I did not show my attempts at using other CI frameworks, all the ones I tried use Ubuntu 12.04 as their base platform, so the first step was to install the necessary tools for C++11 on said platform. Once that problem is resolved, using Travis CI, which appears to be the most popular product, proved relatively easy. In a scale of 1-10 where 1 is booting Android and 10 is configuring sendmail using the original .cf file, I rate this a 2.

The biggest feature I miss from Travis CI is some kind of report to show what specific tests broke or were fixed in each change. The are no plans to implement such a feature (ref). This feature is so important that I may look into using a completely different continuous integration solution, such as Circle CI).