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From: mockturtle on 17 Sep 2009 08:38
Dear all,
I have a question that I am afraid is awfully trivial, but I spent
half a morning without finding any answer.

My setup: I am working with GPS and I have an Ada procedure (say
Interface_to_Addr in foo.adb) that needs to call a small C function
(char *interface_to_ip (char*)) defined in interface_to_ip.c. So, in
my Ada code I wrote

function interface_to_ip(interf : chars_ptr) return chars_ptr;
pragma Import(C, interface_to_ip);

Everything compiles fine, but when it is time to link, the linker
complains (correctly) that it cannot find "interface_to_ip". The
problem is that the compiler does not know that interface_to_ip is in
interface_to_ip.c, or, in other words, it does not know that foo.adb
depends on interface_to_ip.c.

Currently I solved by adding the line

pragma Linker_Options("../../interface_to_ip.o");

and by compiling "by hand" interface_to_ip.c to interface_to_ip.o, but
this solution is *UGLY*.

Everything would be fine if I could tell to the compiler that foo.adb
depends on interface_to_ip.c, but I do not know how to do it. I
looked under the GPS "Project" menu, browsed the GNAT user & reference
manuals (although not in the deepest detail) and googled for a while,
but I could not find an answer.

Thank you in advance for your help.
From: Ludovic Brenta on 17 Sep 2009 09:07
mockturtle wrote on comp.lang.ada:
> Dear all,
> I have a question that I am afraid is awfully trivial, but I spent
> half a morning without finding any answer.
>
> My setup: I am working with GPS and I have an Ada procedure (say
> Interface_to_Addr in foo.adb) that needs to call a small C function
> (char *interface_to_ip (char*)) defined in interface_to_ip.c.  So, in
> my Ada code I wrote
>
>    function interface_to_ip(interf : chars_ptr)  return chars_ptr;
>    pragma Import(C, interface_to_ip);
>
> Everything compiles fine, but when it is time to link, the linker
> complains (correctly) that it cannot find "interface_to_ip".  The
> problem is that the compiler does not know that interface_to_ip is in
> interface_to_ip.c, or, in other words, it does not know that foo.adb
> depends on interface_to_ip.c.
>
> Currently I solved by adding the line
>
>     pragma Linker_Options("../../interface_to_ip.o");
>
> and by compiling "by hand" interface_to_ip.c to interface_to_ip.o, but
> this solution is *UGLY*.
>
> Everything would be fine if I could tell to the compiler that foo.adb
> depends on interface_to_ip.c, but I do not know how to do it.  I
> looked under the GPS "Project" menu, browsed the GNAT user & reference
> manuals (although not in the deepest detail) and googled for a while,
> but I could not find an answer.
>
> Thank you in advance for your help.

I normally use a Makefile to compile in such situations but there are
two alternatives: gprmake and its successor, gprbuild. In GPS, you can
specify that your project is multi-language; this will cause it to
call the proper tool (instead of gnatmake, which is for Ada-only
projects). I cannot be more specific as I don't use GPS myself.
Hopefully the project manager interface in GPS should be intuitive
enough.

--
Ludovic Brenta.
From: Dmitry A. Kazakov on 17 Sep 2009 09:29
On Thu, 17 Sep 2009 05:38:43 -0700 (PDT), mockturtle wrote:

> Dear all,
> I have a question that I am afraid is awfully trivial, but I spent
> half a morning without finding any answer.
>
> My setup: I am working with GPS and I have an Ada procedure (say
> Interface_to_Addr in foo.adb) that needs to call a small C function
> (char *interface_to_ip (char*)) defined in interface_to_ip.c. So, in
> my Ada code I wrote
>
> function interface_to_ip(interf : chars_ptr) return chars_ptr;
> pragma Import(C, interface_to_ip);
>
> Everything compiles fine, but when it is time to link, the linker
> complains (correctly) that it cannot find "interface_to_ip". The
> problem is that the compiler does not know that interface_to_ip is in
> interface_to_ip.c, or, in other words, it does not know that foo.adb
> depends on interface_to_ip.c.
>
> Currently I solved by adding the line
>
> pragma Linker_Options("../../interface_to_ip.o");
>
> and by compiling "by hand" interface_to_ip.c to interface_to_ip.o, but
> this solution is *UGLY*.
>
> Everything would be fine if I could tell to the compiler that foo.adb
> depends on interface_to_ip.c, but I do not know how to do it. I
> looked under the GPS "Project" menu, browsed the GNAT user & reference
> manuals (although not in the deepest detail) and googled for a while,
> but I could not find an answer.

The project file (*.gpr) has "package Linker". You can put linker options
there for example:

package Linker is
for Default_Switches ("ada")
use ("-g", "-lgmem", <...further options...>);
end Linker;

Alternatively, and probably better solution, would be to include the C
source into the project. AFAIK GPS supports C. In that case you should be
able to handle interface_to_ip.c exactly as you do Ada files.

BTW, never use GPS->Project->Edit Project Properties. Notepad is your
friend! (:-))

--
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de
From: mockturtle on 17 Sep 2009 09:32
On Sep 17, 3:07 pm, Ludovic Brenta <ludo...(a)ludovic-brenta.org> wrote:
> mockturtle wrote on comp.lang.ada:
>
>
>
>
>
> > Dear all,
> > I have a question that I am afraid is awfully trivial, but I spent
> > half a morning without finding any answer.
>
> > My setup: I am working with GPS and I have an Ada procedure (say
> > Interface_to_Addr in foo.adb) that needs to call a small C function
> > (char *interface_to_ip (char*)) defined in interface_to_ip.c.  So, in
> > my Ada code I wrote
>
> >    function interface_to_ip(interf : chars_ptr)  return chars_ptr;
> >    pragma Import(C, interface_to_ip);
>
> > Everything compiles fine, but when it is time to link, the linker
> > complains (correctly) that it cannot find "interface_to_ip".  The
> > problem is that the compiler does not know that interface_to_ip is in
> > interface_to_ip.c, or, in other words, it does not know that foo.adb
> > depends on interface_to_ip.c.
>
> > Currently I solved by adding the line
>
> >     pragma Linker_Options("../../interface_to_ip.o");
>
> > and by compiling "by hand" interface_to_ip.c to interface_to_ip.o, but
> > this solution is *UGLY*.
>
> > Everything would be fine if I could tell to the compiler that foo.adb
> > depends on interface_to_ip.c, but I do not know how to do it.  I
> > looked under the GPS "Project" menu, browsed the GNAT user & reference
> > manuals (although not in the deepest detail) and googled for a while,
> > but I could not find an answer.
>
> > Thank you in advance for your help.
>
> I normally use a Makefile to compile in such situations but there are
> two alternatives: gprmake and its successor, gprbuild. In GPS, you can
> specify that your project is multi-language; this will cause it to
> call the proper tool (instead of gnatmake, which is for Ada-only

I did. If I open with an editor the .gpr file created by GPS I find
the line

for Languages use ("Ada", "C");

> projects). I cannot be more specific as I don't use GPS myself.
> Hopefully the project manager interface in GPS should be intuitive
> enough.

Unfortunately I was not able to find any way to "logically connect"
the two files.
I must say that I am maybe using an old version (GPS 4.0.2 from
Help->About), maybe this is easier in the current version. (For
several reasons,
I would avoid updating if possible)

>
> --
> Ludovic Brenta.

From: Ludovic Brenta on 17 Sep 2009 10:49
mockturtle wrote on comp.lang.ada:
> On Sep 17, 3:07 pm, Ludovic Brenta <ludo...(a)ludovic-brenta.org> wrote:
>> I normally use a Makefile to compile in such situations but there are
>> two alternatives: gprmake and its successor, gprbuild. In GPS, you can
>> specify that your project is multi-language; this will cause it to
>> call the proper tool (instead of gnatmake, which is for Ada-only
>
> I did.  If I open with an editor the .gpr file created by GPS I find
> the line
>
>    for Languages use ("Ada", "C");

From memory, this is necessary but not sufficient; you also have to
tick a check box somewhere to tell GPS that your project file is multi-
language. This is confusing, I know, and I learned the hard way :)

--
Ludovic Brenta.


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