BRL-CAD on AIX README
=====================

Building BRL-CAD under AIX is fairly straightforward using a correctly
installed version on the GCC compiler.  If, however, you are using the
IBM Visual Age compiler, then there are additional manual compilation
steps that will be necessary.  In particular, the IBM compiler and
associated standard C library headers are inconsistent with respect to
ANSI/POSIX compliance compiler options.

The IBM compiler supports a variety of compliance options, the two of
particular relevance to building BRL-CAD (in terms of being the close
to obtaining a functional compile) are the strict compliance
(-qlanglvl=stdc89) or "extended" compliance (-qlanglvl=extc89) modes.
Problems encountered in our build environment using strict compliance
does mostly work though we ran into errors in the standard C library
headers.

Using the "extended" complaince mode resolved the standard C library
header issues, but introduces problems in the compilation of BRL-CAD
as the compiler then disables the provision of the __STDC__
preprocessor symbol.  BRL-CAD then defaults back to K&R mode, which
the compiler verbosely refuses to compile.  The "quick fix" that has
been used in the past is to simply swap the compiler between the two
modes as when one fails (e.g. strict), the other usually succeeds
(e.g. extended).  Barring that working, you can use extended mode and
define __STDC__ manually.
