GPL-only code with GPL GNAT?

[vlc <just.another.spam.account@googlemail.com>]

Hi *,

I read in another thread that it would be only allowed to write GPL
code with GNAT. I also remember to have read something like this on
AdaCore's web site for the GPS - GPL version.

I always thought that the GNAT was based on gcc (at least gnatmake is
calling gcc on my PC). With gcc, I can write closed source code, it is
even allowed to link CSS with glibc - there is an extra exception from
the LGPL for glibc made by the FSF.

Does this not hold true with GNAT? And where is the limitation? In the
compiler or in the libraries? I cannot imagine that the GPL puts
restrictions on the compiled code based on the compiler. Maybe the
libraries are dual-licensed under GPL (which allows only linking
against GPL'ed code) and a proprietary license one has to buy?

Thanks a lot for any clearification!