Compiling Open Babel with MinGW on Windows

If you want to compile on Windows using GCC, you have two alternatives: Cygwin's GCC and MinGW's. The one from Cygwin is easier to use (easier installation) but has the disadvantage that the resulting software does not run natively on Windows, various system calls go through Cygwin's emulation layer which slows things down. Here I'll show how to compile Open Babel with MinGW.

Installing MinGW

I've previously found this a bit confusing. This time I did a manual installation by creating a folder C:\MinGW, and then downloading all the relevant dlls on the installation page. To do this quickly just middle click on several links, wait a few seconds, and then hit Save on all the dialog boxes. Once they are all downloaded, move them to C:\MinGW and unzip them there.

Installing MSYS

No need to install MSYS (a kind of build environment for MinGW) for a project such as Open Babel that uses CMake to build. Why do I mention it then? Because the MinGW page talks all about it.

Compiling Open Babel

1. Add C:\MinGW\bin to the PATH
2. Get Cygwin's stuff off the PATH (if it's there). This is most easily accomplished by renaming C:\Cygwin to C:\oldCygwin or so.
3. Configure CMake to create makefiles for MinGW. I had some problems (at runtime) with a shared library version, so I went with the static one:

cmake -G "MinGW Makefiles" ../openbabel-2.3.2 -DWITH_INCHI=FALSE -DBUILD_SHARED=FALSE

4. Build it with MinGW's make.

mingw32-make

Hmmm...I wonder if it's as fast as the MSVC-compiled version we distribute?