Autotools, more properly known as the GNU Build System is a set of shell script-based utilities that automate parts of the configuration and compilation process for software that is distributed as source. The autotools are, in my opinion, a bit over-complex and fragile, but they remain the most portable and standardized way of allowing software to be compiled on UNIX-like (and especially Linux) systems.

One of the parts of autotools, called autoconf, is responsible for creating the “configure script” for a source package. If you’ve ever built a piece of free software from source, you have almost certainly encountered the following venerable triumvirate of commands:

sudo make install

That first command runs the script that is the output of autoconf, and it is responsible for detecting the capabilities and details of the system that the software is being compiled on. It, for example, will check that a sufficiently-recent compiler is available, and what system headers are necessary for various semi-standardized functions that the program uses. One other major function of the configure script is to detect whether or not libraries that the software depends on are available on the system.

The library detection mechanism, however, is biased heavily towards libraries written in C. Since C is of course the lingua franca of the UNIX world, this is understandable. Without cajoling, it really won’t detect libraries written in anything else, unless they have C bindings, and that includes C++. What then do you do if you have a C++ library that you wish to detect using autoconf? If you’re interested in the answer to this question, you probably already know what the problem is, and here I will give two workable solutions.

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