GCC 4.0 vs. 3.5

[Robert Dewar]

I am also in favor of the switch to GCC 4. The time for a major version
switch is when the technology changes in a way that is likely to have
a significant user impact. A large internal change qualifies for this!
Also the change in Fortgran approach is sure to have a signbificant
user impact.

GNAT too will represent a very significant change internally, given the
swith to function at a time and tree-ssa. As for the external interface,
GNAT is *always* changing rapidly in terms of addition of new technology
and features.