Licensing Questions

Licensing Questions

[aditya siram]

Hi all,
Having looked at the Alioth benchmarks I'm looking into Ada as an alternative to C++ but I'm totally confused by the licensing. 

It seems like there's two entities GNU and ADACore both offering the a compiler/runtime but with different restrictions so please excuse these simple questions:
- How are the two products different? Are they just the same codebase with different support models? 
- Can I develop commercial closed-source libraries and software using the GNU version of GNAT?
- Will there be compatibility issues between GNU GNAT and Adacore GNAT beyond missing Ada 2012 features?
- Is AdaCore the only company working on GNAT right now?
- Are there performance differences between the two compilers?

Thanks!
-deech

Re: Licensing Questions

[Niklas Holsti]

On 12-10-20 20:18 , aditya siram wrote:
> Hi all,
> Having looked at the Alioth benchmarks I'm looking into Ada as an alternative to C++ but I'm totally confused by the licensing. 
> 
> It seems like there's two entities GNU and ADACore both offering the a compiler/runtime but with different restrictions so please excuse these simple questions:
> - How are the two products different? Are they just the same codebase with different support models? 
> - Can I develop commercial closed-source libraries and software using the GNU version of GNAT?
> - Will there be compatibility issues between GNU GNAT and Adacore GNAT beyond missing Ada 2012 features?
> - Is AdaCore the only company working on GNAT right now?
> - Are there performance differences between the two compilers?
> 
> Thanks!
> -deech
> 


-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
      .      @       .

Re: Licensing Questions

[Yannick Duchêne (Hibou57)]

Le Sat, 20 Oct 2012 19:18:18 +0200, aditya siram <aditya.siram@gmail.com>  
a écrit:

> Hi all,
> Having looked at the Alioth benchmarks I'm looking into Ada as an  
> alternative to C++ but I'm totally confused by the licensing.
Good choice!

Ludovic Brenta will give you better replies than I, but here we go…

> It seems like there's two entities GNU and ADACore both offering the a  
> compiler/runtime but with different restrictions so please excuse these  
> simple questions:
> - How are the two products different? Are they just the same codebase  
> with different support models?
Same code base, but different support models, indeed.

   * FSF GNAT comes with no support, and a delay of about
     one year lagging behind GNAT Pro/GNAT GPL ;
   * GNAT GPL comes with no support, but benefits from more
     reactive updates than FSF GNAT, while still lagging behind GNAT Pro ;
   * GNAT Pro comes with full support and a very reactive team of long
     time experienced professional Ada developpers.

> - Can I develop commercial closed-source libraries and software using  
> the GNU version of GNAT?

   * With FSF GNAT which comes with the runtime library exception: yes (*)
   * With GNAT GPL: no
   * With GNAT Pro: yes (**)

(*) Beware that some some other conditions may make your applications  
covered by the GPL.
(**) It will even give you the right to use the otherwise GPL additional  
libraries, for any purpose you want, either commercial, open, closed  
source.

> - Will there be compatibility issues between GNU GNAT and Adacore GNAT  
> beyond missing Ada 2012 features?

FSF GNAT is lagging, but that's a matter of delay and patience. GNAT GPL  
is more up to date. GNAT Pro is a lot more up to date than the two  
formers. There are compatibility issues with AUnit (AUnit is to Ada, what  
JUnit is to Java), and both are incompatible.


> - Is AdaCore the only company working on GNAT right now?
As far as I know, yes, except there are people working on GNAT FSF too.

> - Are there performance differences between the two compilers?

No. Except if you need support for no‑runtime variant or any other kind of  
specific runtime meeting specific requirement, then you will need GNAT  
Pro. Otherwise, both provides comparable performances.


-- 
“Syntactic sugar causes cancer of the semi-colons.” [1]
“Structured Programming supports the law of the excluded muddle.” [1]
[1]: Epigrams on Programming — Alan J. — P. Yale University

Re: Licensing Questions

[Niklas Holsti]

On 12-10-20 20:18 , aditya siram wrote:
> Hi all, Having looked at the Alioth benchmarks I'm looking into Ada
> as an alternative to C++ but I'm totally confused by the licensing.

I'll take a shot at answering you. I'm not a lawyer, and my
understanding may be incorrect or incomplete, but here is how I
understand it.

> It seems like there's two entities GNU and ADACore both offering the
> a compiler/runtime but with different restrictions

The GNAT compiler is available with three different licensing schemes:

- GNAT Pro from AdaCore. Expensive, but you can distribute your Ada
programs in binary form (for free or for a price) without distributing
source. And you get support from AdaCore.

- GNAT GPL from AdaCore. Free beer, but with pure GPL, so can be used
only for developing GPL programs.

- GNAT from the Free Software Foundation (FSF; I think this is what you
call "GNU GNAT"). Free beer, and the compiler itself is under GPL, but
the programs that you develop with the compiler are not, because the
libraries use a modified version of GPL that lets you use the libraries
in non-GPL programs.

I use FSF GNAT to compile SW for which I sell binary-only licences in
the traditional fashion.

> so please excuse these simple questions:

> - How are the two products different? Are they just the same codebase
> with different support models?

The codebase is roughly the same; GNAT Pro is most advanced and is
frequently updated. GNAT GPL is a a snapshot of GNAT Pro taken yearly
(more or less). FSF GNAT is maintained by the community but receives
updates from AdaCore (tracking GNAT Pro) now and then.

> - Can I develop commercial closed-source libraries and software using
> the GNU version of GNAT?

With the FSF GNAT, yes. The Debian platform has excellent support for
FSF GNAT, thanks mainly to Ludovic Brenta. For MS Windows, MinGW
provides FSF GNAT (as I understand it). It seems to work, too.

> - Will there be compatibility issues between GNU GNAT and Adacore
> GNAT beyond missing Ada 2012 features?

On the Ada source-code level, for application programs, I don't expect
any compatibility problems.

On the internal level, the ASIS tool-set depends on GNAT internals and
must be closely matched to GNAT, version by version. You cannot use the
GNAT GPL version of ASIS to access compiled code from FSF GNAT. Also, I
would hesitate to mix object code from different GNAT versions in the
same link.

> - Is AdaCore the only company working on GNAT right now?

Yes, for the PC targets, as far as I know. There have been some
companies that have developed off-shoots of GNAT for embedded systems,
for example the XGC company in the UK.

> - Are there performance differences between the two compilers?

Could be, since GNAT Pro is the "wavefront" and so probably has more
evolved optimizations than the other versions.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
      .      @       .

Re: Licensing Questions

[Simon Wright]

Niklas Holsti <niklas.holsti@tidorum.invalid> writes:

> FSF GNAT is maintained by the community but receives updates from
> AdaCore (tracking GNAT Pro) now and then.

Most of the updates to FSF Ada are from AdaCore contributing a massive
input at the start of each release (4.6, 4.7, 4.8); there are
contributions from others in between whiles, but still AdaCore
contribute a very great deal.

Re: Licensing Questions

[Ludovic Brenta]

I'm not going to repeat the good answers from Yannick and Niklas (BTW,
thanks to both for mentioning me :)) but in case you didn't know, there
are other Ada compilers besides GNAT.  The full and complete answer is
in the Ada Programming wikibook:

http://en.wikibooks.org/wiki/Ada_Programming/Installing

The rest of the book is a good read, too, and will anwser many more
questions.

HTH

-- 
Ludovic Brenta.