I don't understand the "gcc" and "gcc3" compiler modules

[Gb]

Hello,

It seems that if I install "gcc" (currently ver 4.2.2),
"gcc3" (3.4.6) gets uninstalled; the other way around is also true.

This may be intentional because "gcc" is defined as "sustained solo",
if I understood correctly.

All this may be fine, but then what is the purpose of the various
GCC_3_4/GCC_4_1/GCC_4_2 menu items in "lunar optimize",
if all I can have is a single compiler version at a time?

Moreover, what is the reason behind having a "GCC3_PREFIX" variable
in the BUILD script of the "qemu" module to select "gcc3" specifically,
if it can be either "the sole compiler" or "not installed"?
There seems to be no selection involved.

And how can be the "qemu" module useful if I want to keep "gcc" (4.2.2)
as the installed compiler?

I am probably confused.
I think I didn't understand the lunar compiler management very well.
Could you please explain this to me?

Thanks,
Gb