[Ada] Bootstrapping mainline GNAT fails (with workaround and root cause: makefile bug)

[Florian Weimer]

Andreas Jaeger <aj@suse.de> writes:

>> I'm not sure if anyone cares, but that's definitely a regression from GCC
>> 2.95.x.  I've been building GCC in a subdirectory of the source directory
>> for years.
>
> AFAIK A (new, empty) subdirectory of the source dir should work - what
> is not supported is building directly in the source dir.  If this is
> broken, it should get fixed,

install.texi reads:

| First, we @strong{highly} recommend that GCC be built into a
| separate directory than the sources which does @strong{not} reside
| within the source tree.  This is how we generally build GCC; building
| where @var{srcdir} == @var{objdir} should still work, but doesn't
| get extensive testing; building where @var{objdir} is a subdirectory
| of @var{srcdir} is unsupported.

That's why I didn't care about the breakage in the Ada run-time
library when OBJDIR is a subdirectory of SRCDIR.