From: Aaron Patterson <aaron@...>
Date: 2009-06-19T07:00:50+09:00
Subject: mkmf.rb questions

I am a very sad panda right now.  I need some help with mkmf.rb.

I have a header file "foo.h" that is in /usr/include.

I have a list of other directories where a newer version of foo.h might
live.  For example, it is possible that I have a newer version of foo.h
installed in either /opt/local/include, /usr/local/include, or some other
directory.

Is there a way with mkmf to detect the newer version of foo.h under one
of the directories in my list?

I'm using find_header(), and the first thing it tries is compiling with
no extra gcc flags.  Since foo.h was already under /usr/include,
find_header() returns true and does not modify the include paths *even
though* I've told it to search other directories.

On top of that, even if I gave gcc a specific -I flag, it will still
return true because the header file is in /usr/include.

What is the "best" way to solve the problem?  I'm tempted to just try
File.exists? for the header file under each possible include directory,
then mucking with the -I flags myself.

Thanks!

-- 
Aaron Patterson
http://tenderlovemaking.com/