NetBSD-6 firefox requires gcc 4.6, why not build 4.8?

[David Brownlee <abs%absd.org@localhost>]

In order to build firefox on netbsd-6 gcc 4.6 or later is required.

Currently gcc 4.6 does not build on netbsd-6

/var/obj/pkg/lang/gcc46/work/gcc-4.6.4/libiberty/alloca.c: In function
'C_alloca':
/var/obj/pkg/lang/gcc46/work/gcc-4.6.4/libiberty/alloca.c:200:5:
warning: implicit declaration of function 'XNEWVEC'
[-Wimplicit-function-declaration]
/var/obj/pkg/lang/gcc46/work/gcc-4.6.4/libiberty/alloca.c:200:43:
error: expected expression before 'char'
Makefile:504: recipe for target 'alloca.o' failed

However, that does raise an interesting point - if an application
requires a version of gcc newer than that shipped with a given system,
why not default to building the highest supported gcc version, rather
than the lowest?

If I'm going to have to build a gcc on netbsd-6, it probably makes
more sense to build 4.8 rather than 4.6, on the grounds that something
else I build later might need 4.8, and one would hope 4.8 would be
generating at least a good code as 4.6...

What do people think?

David