Re: GCC conflict on Ubuntu for mixed Ada/C++ project

[Ludovic Brenta <ludovic@ludovic-brenta.org>]

zeta_no <olivier_henley@hotmail.com> writes:
> Hi to all,
>
> With the distribution of GNAT GPL form Adacore Libre comes some code
> examples like "ada_cpp" that presents mixed Ada/C++ projetcs.  My
> problem is the following: In GPS, for the project to build, we need
> GPRBUILD which uses GCC and the -gnat05 option.  Well, using GPRBUILD,
> the ouput of a BUILD ALL tells me that GCC 4.4 installed by Ubuntu was
> triggered, not GCC 4.3 coming with the GNAT distro.  How do I tell GPS
> and GPRBUILD to use the good GCC? The problem is on the Ubuntu side or
> GPRBUILD?
>
> We have to admit that my setup is ugly.  I use GPS and GPRBUILD from
> Adacore, but GNAT from Ubuntu.  That's not all.  I don't know why, but
> by using GNAT from Ubuntu, the second example from ada_cpp,
> animals.gpr, does not compile at all. I get the following error
> mesage:
>
> cannot import abstract subprogram "Number_Of_Teeth" declared at line
> 5.
> cannot imp...
>
> If someone could help me with my problem of GNAT versioning to resolve
> the good use of GCC, I would really appreciate.  Just to confirm, I
> did exported /usr/gnat/bin into my PATH env. variable.

Out of curiosity I reproduced your problem on Debian with the following
packages installed:

ii  gnat           4.4+1          The GNU Ada compiler
ii  gnat-4.4       4.4.4-2        The GNU Ada compiler
ii  gnat-4.4-base  4.4.4-2        The GNU Compiler Collection (gnat base packa
ii  gprbuild       1.3.0-1        a multi-language extensible build tool
ii  gprbuild-doc   1.3.0-1        a multi-language extensible build tool

What I did:

$ cp -a /usr/share/doc/gprbuild-doc/examples/ada_cpp .
$ cd ada_cpp
$ make
gprconfig --batch --config Ada,,sjlj  --config C++ -o default.cgpr
Creating configuration file: default.cgpr
gprbuild animals.gpr
gcc-4.4 -c -g -gnat05 -gnatwA main.adb
animals.ads:33:24: cannot import abstract subprogram "Number_Of_Teeth" declared at line 5
animals.ads:36:24: cannot import abstract subprogram "Set_Owner" declared at line 10
gprbuild: *** compilation phase failed
make: *** [all] Error 4

As you can see, this has nothing to to with GPS, gnatmake or gprbuild
and everything to do with gnat-4.4.

The version of gprbuild that Stephe packaged for Debian is identical to
that in GNAT GPL 2009, which has new functionality to help interfacing
Ada with C++.  gnat-4.4 lacks some of these features; it can iterface
with C++ but in more limited ways.  One interesting feature that is new
in GNAT GPL 2009 is the ability to generate an Ada spec file from C++
header files (i.e. g++ -fdump-ada-spec file.h).

If you want to use these latest features, you should use a clean
installation of GNAT GPL 2009; make sure you set your $PATH correctly to
see the GNAT GPL compiler and NOT the Ubuntu compiler.

-- 
Ludovic Brenta.