Re: [gentoo-dev] Changes in toolchain.eclass to enable Ada

[Michał Górny]

On Wed, 21 Dec 2016 23:00:47 +0100
Alfredo Tupone <tupone@g.o> wrote:

> I would like to revive the Ada support in gentoo.
>
> One ada compiler is produced by AdaCore and is provided in three
> versions, in the order starting from the best supported :
>
> 1) GnatPro, available with a contract support.
>
> 2) Gnat-GPL that can only build GPL-3 product
>
> 3) The gnat included in the gcc tree that is GPL-3 with exception.
>
> Gnat-GPL is very like the gnat in the gcc-tree so it can be built in
> the same way of sys-devel/gcc
>
> To be compiled from source the gcc compiler needs a C, C++, and Ada
> Compiler. I will provide one with the gnat-gpl-bin tar that could be
> installed under /opt . When the gcc is properly compiled we don't need
> it any more.

Do I correctly understand that this is also true for gnat-gpl? Is there
any Ada compiler that could be used to bootstrap Ada on platforms that
lack prebuilt binaries?

> I would like to start including, in the gentoo tree, GNAT-GPL
> built in the same way as sys-devel-gcc and selectable with gcc-config

1. Does this mean that GNAT-GPL build will include building a C
compiler? If yes, will the C compiler be installed?

2. Will it be possible to combine GNAT-GPL with a different version of
regular gcc C/C++ compilers?

> As for instance gnat-gpl-2014 is based on gcc-4.7.4 they cannot coexist
> and gnat-gpl-2014 will block sys-devel/gcc-4.7.4

Block the whole sys-devel/ or just sys-devel/gcc[ada]?

> As a reference I have my overlay on https://github.com/atupone/overlay
> and a pull request at https://github.com/gentoo/gentoo/pull/3186
>
> To start I need to change the toolchain.eclass
>
> -	tc_version_is_at_least 4.7 && IUSE+=" go"
> +	tc_version_is_at_least 4.7 && IUSE+=" go ada"
>
> -	# We do NOT want 'ADA support' in here!
> -	# is_ada && GCC_LANG+=",ada"
> +	# We do want 'ADA support' here!
> +	is_ada && GCC_LANG+=",ada"
>
> -	for x in cpp gcc g++ c++ gcov g77 gcj gcjh gfortran gccgo ; do
> +	for x in cpp gcc g++ c++ gcov g77 gcj gcjh gfortran gccgo gnatbind; do
>
> Thats all for that.
>
> Then, to not change the behaviour of the gcc-compiler, we could mask the
> ada use flag for sys-devel/gcc, at least temporarily
>
> ---------------------
>
> I would like to have comments on that, particularly because:
> a) it is going to add a use flag to sys-devel/gcc that will bring gcc
> to be rebuilt on most system,

That's a minor problem. Toolchain people do this on us all the time,
so...

> b) the gnat-gpl, if selected with gcc-config, can be used to recompile
> all the system, and maybe is not so good ?

I don't really understand what you mean here. But it's probably related
to the questions I asked above.

-- 
Best regards,
Michał Górny
<http://dev.gentoo.org/~mgorny/>