llvm dev - May 2014 - [LLVMdev] [ exception_ptr ] libcxx doesn't cope well with libcxxabi under linux

Since the original buildit script doesn't cover my needs I switched to a
custom but really similar script, in the meantime I also got the habit
to dig for new flags and support and the __GLIBCXX__ define was hiding 
some of this errors. I see that other linux-based operating system offer this
kind of support and they even use the same core components of my
GNU/Linux distribution.

You are right, 
in the end I get this warnings but how I'm supposed to fill the voids ? 
In other words why I should user libc++ under linux and what are the 
benefits ? I should go for libstdc++ and libsupc++ ?
Il Giovedì 1 Maggio 2014 3:49, Jonathan Roelofs <jonathan at
codesourcery.com> ha scritto:
 
+cfe-dev

Emanuele,

On 4/30/14, 6:07 PM, Emanuele Cestari wrote:
> Hi,
> I'm under Ubuntu 13.10 amd64 I just compiled both my libcxx and my
libcxxabi.
>
> I noticed this really weird behaviour, while trying to compile some
> C++11-compliant piece of code I get this error at runtime
>
> exception_ptr not yet implemented
> Aborted (core dumped)
>
Didn't you hit similar warnings when you built libc++abi & libc++? That
would
suggest that libc++ and libc++abi haven't been fully ported to your platform
yet.
>
> What I would like to know is: there is a good reason for this or it's a
bug ?
>
> Aside from that, libcxxabi is able to provide a complete ABI implentation
under
> linux without libsupc++ and libstdc++ ?
I believe you'll still need to link against libgcc_s in order to get EH
support
on linux.
>
> Thanks.
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu        http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
-- 
Jon Roelofs
jonathan at codesourcery.com
CodeSourcery / Mentor Embedded
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01.05.2014, 20:18, "Emanuele Cestari" <emanuelecestari at
yahoo.com>:
> Since the original buildit script doesn't cover my needs I switched to
a custom but really similar script, in the meantime I also got the habit to dig
for new flags and support and the __GLIBCXX__ define was hiding some of this
errors. I see that other linux-based operating system offer this kind of support
and they even use the same core components of my GNU/Linux distribution.
>
> You are right, in the end I get this warnings but how I'm supposed to
fill the voids ? In other words why I should user libc++ under linux and what
are the benefits ? I should go for libstdc++ and libsupc++ ?
You can try libcxxrt instead of libc++abi


-- 
Regards,
Konstantin

I understand that there are alternatives but in my opinion there are some subtle
messages that suggest otherwise scattered all around the llvm project and
sub-projects, let me give you a list of what I think should be more explicit or
done differently:

 - the official binary packages ( from llvm.org/releases/download.html ) for
clang include libcxx headers, suggesting that there some kind of full or
official support for libcxx under Ubuntu or any other GNU/Linux based
distribution

 - the official libcxxabi website states that libcxxabi is complete and there is
full support for linux, even the matrix tracking the current status of the
project confirms that http://libcxxabi.llvm.org/spec.html

 - the cmake based build makes this weird difference between libstdc++ and
libsupc++ and both names are accepted as ABI options, libstdc++ is not an ABI
library, this is highly misleading for newcomers and I still don't have a
good idea about why that option is there


Generally speaking there is also the word "linux" that is misleading
in my opinion, this word it's scattered all around the llvm docs and
projects, and if you ask me what is a typical "linux" based system, I
would say any system with a GNU/Linux distribution installed using libstdc++ as
the standard C++ library and libsupc++ or libcxxrt as the ABI library . Even
some router or a generic Android based hardware can be labeled as a
"linux" system.


Now I understand that with the word "linux" the developers mean some
generic IBM machine running the linux kernel plus some in-house developed
standard library.

I think that the guidelines should make this more explcit, meaning blacklisting
the use of a generic word such as "linux" in such cases, but force to
always describe the targeted system in a more unique and specific way, just like
the triple does, in any doc or reference to any project there should be an
explicit reference to the name of the ABI, the name of the standard library, the
configuration of the system that it's used to run the test, if the given
project or a part of it is vendor specific and so on; just 3 or 4 names that can
make a big difference.


Plus the official releases for an unsupported platform shouldn't include a
project or a part of it that is unsupported for the given platform, even if you
give me the header for libcxx, I'm using libstdc++ and libsupc++ anyway, why
bothering including a misleading option that I will not be able to use and
I'm inclined to label as "broken" judging from what I get from the
official website.


I think that minor changes in the policy can really make a difference and make
the llvm project more reliable in its entirety.

Il Giovedì 1 Maggio 2014 21:00, Konstantin Tokarev <annulen at yandex.ru>
ha scritto:
 

01.05.2014, 20:18, "Emanuele Cestari" <emanuelecestari at
yahoo.com>:
> Since the original buildit script doesn't cover my needs I switched to
a custom but really similar script, in the meantime I also got the habit to dig
for new flags and support and the __GLIBCXX__ define was hiding some of this
errors. I see that other linux-based operating system offer this kind of support
and they even use the same core components of my GNU/Linux distribution.
>
> You are right, in the end I get this warnings but how I'm supposed to
fill the voids ? In other words why I should user libc++ under linux and what
are the benefits ? I should go for libstdc++ and libsupc++ ?
You can try libcxxrt instead of libc++abi


-- 
Regards,
Konstantin
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