Friday, August 19, 2005

GNU autotools lessons learned

Along the way to autoconfiscating portions of our Windows to Linux port for my company's desktop softare, I discovered the autoreconf gem. It handles most of what I had stuffed into a autogen.sh script.

One nit. I have some custom macros in an m4/ subdirectory which add support for --enable-debug, --enable-profile and --enable-release flags to ./configure. (Why aren't these standard, or at least the macros standard?) autoreconf supports an -I m4 option to pass these to autoconf and autoheader, but not to aclocal.

Drat!

However, thanks to GNU Automake by Example, I found that I can put a ACLOCAL_AMFLAGS = -I m4 line in the top-level Makefile.am to pass -I m4 to aclocal. This is an unfortunate code duplication, but better than simply having the feature broken.

I also discovered autoupdate which brought my configure.ac file up to current standards. Nifty.

Lastly, I saw that autoreconf is actually quite clever. If I have never run ./configure, the --make option does nothing as it does not know how I wish to configure the project (the install directory, for example). However once I have run ./configure, autoreconf reuses the settings from that first run for subsequent runs of ./configure and then dashes off with make afterwards.

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