MacPorts should require the latest Xcode

[Ryan Schmidt]

Here's a message from the -users list just now:

On Jul 28, 2007, at 18:39, Chris Waterson wrote:

> Hey, I had the same problem.  It turns out I was using an older  
> version of Xtools (specifically, version 2.3).  After upgrading to  
> Xtools 2.4.1, things worked fine.  (The specific trouble, which you  
> can see if you get rid of the "-j2" option in the makefile, is that  
> they've changed some of the defines in the header files that the  
> boehm-gc needs.)

Problems caused by old Xcode versions are reported by users with some  
regularity. I suppose we could add something to the FAQ, but users  
don't always read the FAQ, and the first step of the first section of  
the installation guide already reads: "Download and install the  
latest version of Xcode Tools—do not install an older version from  
the OS X 10.4 install disk or some ports may fail to install."

We should not allow users to run into this problem. Can we please  
modify MacPorts base to issue a fatal error and refuse to do anything  
unless the latest Xcode (2.4.1 on 10.4.x, 1.5.x on 10.3.x) is  
installed? I think this would be a good idea. When new versions of  
Xcode are released, we can update base as needed.