16.4.1 Testing C++ Implementations with Autoconf

Of the GNU Autotools, perhaps the most valuable contribution to the portability of your C++ programs will come from Autoconf. All of the portability issues raised in 16.2 Changeable C++ can be detected using Autoconf macros.

Luc Maisonobe has written a large suite of macros for this purpose and they can be found in the Autoconf macro archive (see section 23.5.1 Autoconf macro archive). If any of these macros become important enough, they may become incorporated into the core Autoconf release. These macros perform their tests by compiling small fragments of C++ code to ensure that the compiler accepts them. As a side effect, these macros typically use AC_DEFINE to define preprocessor macros of the form HAVE_feature, which may then be exploited through conditional compilation.