fatal error: file gnat1drv.ali is incorrectly formatted

[Duncan Sands]

> The failure you got is building gnat1, not the run time library.
> I'd suggest doing a make clean and a clean build again.

Hi Arnaud, the problem occurs because the bootstrap is (wrongly) using
something from the --prefix directory given during configuration (an old
version of the compiler lives there).  If that directory is empty there is
no problem.  I'm trying to work out what exactly is going on.

D.