[Boost-build] Auto-select the 'best' gcc available?

Subject: [Boost-build] Auto-select the 'best' gcc available?
From: alexrichardson_at_[hidden]
Date: 2008-11-07 11:57:48

I am attempting to replace a home-grown build system with boost.build. I  
have just a couple days of experience with boost.build, so I am very new.

One of the features of the previous system was that it would auto-select  
the version of gcc to use on a machine by using the first version that  
showed up on a list. (Most of the build machines have mutliple versions of  
gcc installed.) So, the build system would have a list such as:

gcc-4.3
gcc-4.1
gcc-3.4

The build system would first attempt to use gcc-4.3, if it was not  
available on the machine, it would try 4.1, etc... I would like to get  
similar functionality from boost.build. My naive approach was to create a  
site-config.jam file with something along the lines of:

using gcc : 4.3 : gcc-4.3 ;
using gcc : 4.2 : gcc-4.2 ;
using gcc : 4.1 : gcc-4.1 ;

This seemed to result in the system trying to build the project 3 times,  
once for each gcc version. Also, the 'list' of gcc versions needs to be  
specified on a per-project basis. Ie for some projects, gcc-3.x is  
the 'best' compiler, because gcc 4.x will not work.

So in summary: Is there a way to specify something along the lines of:

if gcc-4.3 exists, use it
else if gcc-4.2 exists, use it,
else if gcc-4.1 exists, use it, etc.....