Query on building Gnat-4.9 from source.

[Brian Drummond <brian@shapes.demon.co.uk>]

In the past I have only built my own compilers from upstream sources,
rather than "the Debian way".

Now I have found an issue with a Debian (but not upstream) Gnat build
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=749574
and thought to take a look at the Debian sources...
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apt-get -t testing source gnat-4.9
su
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apt-get -t testing build-dep gnat-4.9
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Selected version '4.9.0-1' (testing) for gnat-4.9
The following packages have unmet dependencies:
 gnat : Depends: gnat-4.6 (>= 4.6.4-2) but it is not going to be
installed
E: Build-dependencies for gnat-4.9 could not be satisfied.
-----------------------------------------------

Now it seems that (having installed gnat-4.9) I shouldn't need to
install a gnat-4.6 version in order to rebuild gnat-4.9 from source : so
if you'll forgive a newbie question, what am I doing wrong here?

- Brian