So, it is always tempting to be at the latest greatest of some software. For example, Sun (Solaris) Studio 12 update 3 is freely available to download. But sometimes the latest will leave you with some head scratching.
Some Python modules require a C compiler in order to provide a faster runtime, or even to install at all. Numpy is one such module. It provides superb capabilities in Python, but even doing:
# pip install numpy
It will still invoke the C compiler. Due to how the Python interpreter was compiled on OpenIndiana, by using the latest compiler (installed, say, in /opt/solarisstudio12.3), your install will fail. Using the Sun Studio in the opensolaris.org repository (yes, the old 12.1), things work great, as it is installed in /opt/sunstudio12.1
So if you encounter a failed install of a Python module under OpenIndiana, there is a good chance you hit the above problem.