Questions about libc++ for linux and its git repository (if any)

Clang Frontend
1

Hi there,

I just started using llvm and clang so forgive me for this
very simple question.

I'm looking for a git repository for the libcxx (the libcxx.llvm.org
website only list svn) and also looking for some info about the
current Linux support.

Thanks,
Salvatore

2

If no git repository is available you can always do a "git svn clone".

3

Hi there,

I just started using llvm and clang so forgive me for this
very simple question.

I'm looking for a git repository for the libcxx (the libcxx.llvm.org
website only list svn) and also looking for some info about the
current Linux support.

I don't know what other projects (apart llvm and clang) are available here, but libcxx can be found at http://llvm.org/git/libcxx.git and compiler-rt at http://llvm.org/git/compiler-rt.git

Thanks,
Salvatore
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-- Jean-Daniel

4

Perfect thanks! May I suggest to have that listed in the project page?

Anyway what about the Linux support? Where do I start from?

I wanted to start using it for a project of mine (clang++ & libcxx) in
C++11, and even though
I'm not a C++ guru, some part of the STL should still be usable right?
As long as I pass my own
allocator to a container for instance, I should have not problem using
it (exception and memory allocation
excluded).

How do I tell clang++ where to look for libcxx (excluded the obvious
-I option)? Any readings you can point me
too?

Thanks again.

Regards,
Salvatore

5

If you checkout the libcxx project in the llvm sources (in projects/libcxx) and build/install clang using autoconf, the headers will automatically be installed where clang++ driver expects them.

You can also install them manually in "<prefix>/lib/c++ /v1".

When invoking clang++, don't forget to pass "-stdlib=libc++" to tell clang you want to use libc++.

I never tried to use it on Linux, so I can't tell where clang look for the libc++ binary when it invoke the linker. You may have to copy it in a standard path (/usr/lib or /usr/local/lib).

-- Jean-Daniel

6

Hi there,

I just started using llvm and clang so forgive me for this
very simple question.

I'm looking for a git repository for the libcxx (the libcxx.llvm.org
website only list svn) and also looking for some info about the
current Linux support.

I don't know what other projects (apart llvm and clang) are available here, but libcxx can be found at http://llvm.org/git/libcxx.git and compiler-rt at http://llvm.org/git/compiler-rt.git

Perfect thanks! May I suggest to have that listed in the project page?

Anyway what about the Linux support? Where do I start from?

I wanted to start using it for a project of mine (clang++ & libcxx) in
C++11, and even though
I'm not a C++ guru, some part of the STL should still be usable right?
As long as I pass my own
allocator to a container for instance, I should have not problem using
it (exception and memory allocation
excluded).

How do I tell clang++ where to look for libcxx (excluded the obvious
-I option)? Any readings you can point me
too?

If you checkout the libcxx project in the llvm sources (in projects/libcxx) and build/install clang using autoconf, the headers will automatically be installed where clang++ driver expects them.

OK, re-running configure gives me the following in config.log

configure:3508: WARNING: Unknown project (libcxx) won't be configured
automatically

which doesn't look very good. I pulled libcxx into projects.

You can also install them manually in "<prefix>/lib/c++ /v1".

OK, how do I build and configure it outside llvm? The project page
doesn't say much,
except for running builtit.

When invoking clang++, don't forget to pass "-stdlib=libc++" to tell clang you want to use libc++.

I never tried to use it on Linux, so I can't tell where clang look for the libc++ binary when it invoke the linker. You may have to copy it in a standard path (/usr/lib or /usr/local/lib).

OK perfect.

Thanks,
Salvatore

7

Hi there,

I just started using llvm and clang so forgive me for this
very simple question.

I'm looking for a git repository for the libcxx (the libcxx.llvm.org
website only list svn) and also looking for some info about the
current Linux support.

I don't know what other projects (apart llvm and clang) are available here, but libcxx can be found at http://llvm.org/git/libcxx.git and compiler-rt at http://llvm.org/git/compiler-rt.git

Perfect thanks! May I suggest to have that listed in the project page?

Anyway what about the Linux support? Where do I start from?

I wanted to start using it for a project of mine (clang++ & libcxx) in
C++11, and even though
I'm not a C++ guru, some part of the STL should still be usable right?
As long as I pass my own
allocator to a container for instance, I should have not problem using
it (exception and memory allocation
excluded).

How do I tell clang++ where to look for libcxx (excluded the obvious
-I option)? Any readings you can point me
too?

If you checkout the libcxx project in the llvm sources (in projects/libcxx) and build/install clang using autoconf, the headers will automatically be installed where clang++ driver expects them.

OK, re-running configure gives me the following in config.log

configure:3508: WARNING: Unknown project (libcxx) won't be configured
automatically

This is expected. libc++ does not require "configuration" step. Nonetheless, "make install" will properly find the libc++ headers and install them where needed.

which doesn't look very good. I pulled libcxx into projects.

You can also install them manually in "<prefix>/lib/c++ /v1".

OK, how do I build and configure it outside llvm? The project page
doesn't say much,
except for running builtit.

There is no configure or install script in libc++. You run buildit to build the dynamic library, and then you have to copy it where needed

When invoking clang++, don't forget to pass "-stdlib=libc++" to tell clang you want to use libc++.

I never tried to use it on Linux, so I can't tell where clang look for the libc++ binary when it invoke the linker. You may have to copy it in a standard path (/usr/lib or /usr/local/lib).

OK perfect.

Thanks,
Salvatore

-- Jean-Daniel

8

We had a chat about this a little while ago, you may find something useful in this thread:
http://thread.gmane.org/gmane.comp.compilers.clang.devel/22540

tldr; libc++ requires an abi and unwind library, there are options.

Hopefully I'll get round to testing this and writing up a guide on the weekend.

Ben

9

....

OK, re-running configure gives me the following in config.log

configure:3508: WARNING: Unknown project (libcxx) won't be configured
automatically

This is expected. libc++ does not require "configuration" step. Nonetheless, "make install" will properly find the libc++ headers and install them where needed.

What about cross-compiling? I configured llvm in order to have
different targets (arm and x86_64).
Is the libcxx automagically compiled for both architecture?

Anyway I did install it just fine. I only had to remove a chgrp
root:wheel as I don't have
that group on my ubuntu, and honestly don't even know what it is. :slight_smile:

S.

10

Unfortunately is not working out of the box and not even by adding the
path with isystem.

$ clang++ -ccc-gcc-name arm-none-linux-gnueabi-g++ -ccc-host-triple
thumbv7m-none-gnueabi -stdlib=libc++ -print-search-dirs
programs: =/home/emitrax/bin/llvm/bin
libraries: =/home/emitrax/bin/llvm/bin/../lib/clang/3.2

which is OK only for clang. That's where I've installed everything.

$ clang++ -stdlib=libc++ -print-search-dirs
programs: =/home/emitrax/bin/llvm/bin:/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../../x86_64-linux-gnu/bin
libraries: =/home/emitrax/bin/llvm/bin/../lib/clang/3.2:/usr/lib/gcc/x86_64-linux-gnu/4.6:/usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu:/lib/x86_64-linux-gnu:/lib/../lib64:/usr/lib/x86_64-linux-gnu:/usr/lib/gcc/x86_64-linux-gnu/4.6/../../..:/lib:/usr/lib

still wouldn't find the headers for c++ as the are under
/home/emitrax/bin/llvm/lib/c++/v1

It only find the wanted header if I use the obvious
-I/home/emitrax/bin/llvm/lib/c++/v1, but beside being
utterly wrong, it gives me other errors like global symbols missing.

In file included from /home/emitrax/bin/llvm/lib/c++/v1/list:177:
In file included from /home/emitrax/bin/llvm/lib/c++/v1/algorithm:596:
/home/emitrax/bin/llvm/lib/c++/v1/cstdlib:96:9: error: no member named
'lldiv_t' in the global namespace
using ::lldiv_t;
      ~~^
/home/emitrax/bin/llvm/lib/c++/v1/cstdlib:100:9: error: no member
named 'atoll' in the global namespace
using ::atoll;

Any suggestions about how to fix this ?

Regards,
Salvatore