Re: Add clang++ to AC_PROG_CXX

[Ruben Safir]

On 03/31/2016 12:49 PM, Ruben Safir wrote:
> On 03/31/2016 12:31 PM, Jeffrey Walton wrote:
>>>> That is not a bug, it was a desired feature...
>>>
>>> Huh. How is not finding a viable compiler when one is present a desired 
>>> feature?
>>
>> +1. I kinda laughed when I read that, too.
>>
>> Apparently the project has a set of goals, and breaking the
>> configuration and compile in some instances meets the goals. Hence the
>> reason I laughed.
>>
>> Jeff
>>
>> _______________________________________________
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>>
> http://gcc.gnu.org/ml/gcc/2014-01/msg00247.html
> 
> 
> Re: clang vs free software
> 
>     From: Richard Stallman <rms at gnu dot org>
>     To: gcc at gcc dot gnu dot org
>     Date: Fri, 24 Jan 2014 09:54:13 -0500
>     Subject: Re: clang vs free software
>     Authentication-results: sourceware.org; auth=none
>     References: <CAJnXXoi2MLpZWxOxknR=mNR91JdZcHrKRsqYZSWY373fvwxObg at
> mail dot gmail dot com> <87eh439w1n dot fsf at uwakimon dot sk dot
> tsukuba dot ac dot jp>
> <CAJnXXojjSAWL8cqZp0X16xa81R73huywtTS90p6O3CpRaPOiDQ at mail dot gmail
> dot com> <jwvwqhu8zcg dot fsf-monnier+emacs at gnu dot org> <87ha8yqvup
> dot fsf at engster dot org> <E1W5cXI-0000j4-8x at fencepost dot gnu dot
> org> <CAJnXXoiuzZhjDGpvXY7psee=+bXn1rB+GdELYP0FS0CuWPqYeQ at mail dot
> gmail dot com> <E1W6HwP-0001WU-Tg at fencepost dot gnu dot org>
> <87r47zezcc dot fsf at fencepost dot gnu dot org> <m2eh3ykc3y dot fsf at
> gmail dot com> <20140123174934 dot GA10933 at thyrsus dot com>
>     Reply-to: rms at gnu dot org
> 
> [[[ To any NSA and FBI agents reading my email: please consider    ]]]
> [[[ whether defending the US Constitution against all enemies,     ]]]
> [[[ foreign or domestic, requires you to follow Snowden's example. ]]]
> 
> In the free software movement, we campaign for the freedom of the
> users of computing.  The values of free software are fundamentally
> different from the values of open source, which make "better code" the
> ultimate goal.  If GCC were to change from a free compiler into a
> platform for nonfree compilers, it would no longer serve the goal of
> freedom very well.  Therefore, we had to take care to prevent that.
> 
> (See http://www.gnu.org/philosophy/open-source-misses-the-point.html
> for more explanation of the difference between free software and open
> source.  See also http://thebaffler.com/past/the_meme_hustler for
> Evgeny Morozov's article on the same point.)
> 
> The Clang and LLVM developers reach different conclusions from ours
> because they do not share our values and goals.  They object to the
> measures we have taken to defend freedom because they see the
> inconvenience of them and do not recognize (or don't care about) the
> need for them.  I would guess they describe their work as "open
> source" and do not talk about freedom.  They have been supported by
> Apple, the company which hates our freedom so much that its app store
> for the ithings _requires_ all apps to be nonfree. (*)
> 
> The nonfree compilers that are now based on LLVM prove that I was
> right -- that the danger was real.  If I had "opened" up GCC code for
> use in nonfree combinations, that would not have prevented a defeat;
> rather, it would have caused that defeat to occur very soon.
> 
> For GCC to be replaced by another technically superior compiler that
> defended freedom equally well would cause me some personal regret, but
> I would rejoice for the community's advance.  The existence of LLVM is
> a terrible setback for our community precisely because it is not
> copylefted and can be used as the basis for nonfree compilers -- so
> that all contribution to LLVM directly helps proprietary software as
> much as it helps us.
> 
> The cause of the setback is the existence of a non-copylefted compiler
> that therefore becomes the base for nonfree compilers.  The identity
> of that compiler -- whether it be LLVM, GCC, or something else -- is a
> secondary detail.  To make GCC available for such use would be
> throwing in the towel.  If that enables GCC to "win", the victory
> would be hollow, because it would not be a victory for what really
> matters: users' freedom.
> 
> If you think we ought to "compromise" on this point, please see
> http://www.gnu.org/philosophy/compromise.html.
> 
> The only code that helps us and not our adversaries is copylefted
> code.  Free software released under a pushover license is available
> for us to use, but available to our adversaries just as well.  If you
> want your work to give freedom an advantage, use the leverage
> available to you -- copyleft your code.  I invite those working on
> major add-ons to LLVM to release them under GNU GPL
> version-3-or-later.
> 
> 
> If you want to argue for changing the goals of the GNU Project, the
> proper place to do this is address@hidden  Please move this
> discussion there.
> 
> 
> * If a binary is made from published source code, but you can't
>   install your binary of a modified version of that source code, the
>   binary is proprietary even if the source code is free.  (See
>   http://www.gnu.org/philosophy/free-sw.html.)  A binary in Apple's
>   app store may be made from published free source code, but under
>   Apple's rules and Apple's DRM, the binary can't be free.
> 

https://gcc.gnu.org/ml/gcc/2014-01/msg00209.html

(Redirected to the proper lists, excluding emacs-devel.)

Helmut Eller <address@hidden>:
> > If nobody bothers with even
> > considering the question, it would appear that it is not all that
> > important...
>
> Maybe nobody bothers because using clang is easier than to fight with
> FSF policies.

Which is pretty close if not identical to my original point.

The clang people aren't just a technical challenge to GCC, they're a
philosophical/political one to the FSF as well.  They are explicitly
reacting, and positioning themselves publicly against, what they
consider FSF over-control.

The clearest possible statement of this is in Chandler Carruth's talk
"Clang: Defending C++ from Murphy's Million Monkeys" (all over
YouTube) in which he explains "why we set out to build another C++
compiler" by beginning with this question posted to the gcc list: "is
there are reason for not making the [GCC] front ends dynamic
libraries which could be linked by any program that wants to parse
source code?"

Carruth then quotes RMS: "One of our main goals for GCC is to prevent
any parts of it from being used together with non-free software.
Thus, we have deliberately avoided many things that might possibly have
the effect of facilitating such usage..."

Carruth then says, exasperation very obvious in his voice, "This is *not*
a *useful answer*!" (about 3:42 in the video). Thus, the clang project.
 They
want to build IDEs and other tools that share the compiler's code.  GCC
policy won't let them do that.  Ergo, GCC must be kicked aside.

The clang developers are demonstrating that they have the capacity to make
good on this threat.  clang is not a toy or a laboratory demonstration; it
is a real, production-quality compiler with some significant advantages over
GCC.  Much more useful error messages is one; a newer generation of
optimization leading to smaller, tighter code is another; and much faster
compilation is yet another.

The "Clang vs Other Open Source Compilers" page admits that "GCC
supports more targets than LLVM" and "GCC supports languages that
clang does not aim to", but these are not stable advantages given the
technical strength of LLVM and the large amount of developer
commitment clang now has.

I'm not pointing out these facts to argue with the FSF's past decisions,
but to ask "What are you going to do now?"

More of the same will not serve.  GCC is in near-term danger of losing
its dominance in open-source C development; I would say the danger is
imminent if not that people are innately conservative about major changes
to their toolchains.  The other shoe will drop when a major Linux
distribution
ships with clang as its default compiler; I could easily see this happening
before the end of 2015, followed by a cascade of me-too defections.

To keep its #1 spot, GCC needs to out-improve and out-compete clang.
And not just on the technical level, either. "Using clang is easier
than to fight with FSF policies" indeed.  Unless that changes, GCC's
future is as a legacy tool, a backwater that developers are exiting
as fast as is practical.

As I've said before, I don't personally care who wins; either tool
will serve my needs.  I would prefer to see both flourish and
compete with each other. But that's not where things are heading
unless GCC ups its game.
-- 
                <a href="http://www.catb.org/~esr/";;>Eric S. Raymond</a>
-- 
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