Re: [boost] Clang 3.4 failing to compile boost 1.57 headers

Subject: Re: [boost] Clang 3.4 failing to compile boost 1.57 headers
From: Bjørn Roald (bjorn_at_[hidden])
Date: 2015-01-18 04:10:27

On 18. jan. 2015 07:17, Robert Dailey wrote:

> Thanks for the quick feedback everyone! How do I check what library
> its using? I'm not very comfortable in linux environment and I've done
> most of my development on Windows. Really appreciate the help.

If you add -v on the command line to clang++ it will tell you.
Look for a line like:
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/4.8

Here is a one line command you may try.
echo '#include <vector>' | clang++ -c -xc++ -v -o /dev/null -

-c 		is compile only
-xc++ 		specify language for STDIN input file
-o /dev/null	throw away the output
-		specify to use STDIN as input

You may also just look around for the library files, but you sort of 
need to know where:

ls -l /usr/include/c++
lists 2 directories and a symbolic link on my system:
drwxr-xr-x 12 root root 4096 nov.  20 16:40 4.8
lrwxrwxrwx  1 root root    3 april  5  2014 4.8.2 -> 4.8
drwxr-xr-x  5 root root 4096 des.  13 16:08 v1

v1 is for libc++
4.8 is for libstdc++

find /usr/lib -name "*c++*"
/usr/lib/gcc/x86_64-linux-gnu/4.8/libstdc++.so
/usr/lib/gcc/x86_64-linux-gnu/4.8/libstdc++.a
/usr/lib/gcc/x86_64-linux-gnu/4.8/libsupc++.a
/usr/lib/x86_64-linux-gnu/sigc++-2.0
/usr/lib/x86_64-linux-gnu/sigc++-2.0/include/sigc++config.h
/usr/lib/x86_64-linux-gnu/libc++.so.1.0
/usr/lib/x86_64-linux-gnu/libc++abi.so
/usr/lib/x86_64-linux-gnu/libc++.so~
/usr/lib/x86_64-linux-gnu/libc++abi.a
/usr/lib/x86_64-linux-gnu/libstdc++.so.6
/usr/lib/x86_64-linux-gnu/libc++.so
/usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.19
/usr/lib/x86_64-linux-gnu/libc++.so.1
/usr/lib/x86_64-linux-gnu/libc++.a
/usr/lib/x86_64-linux-gnu/pkgconfig/sigc++-2.0.pc

If you try to use -stdlib=libc++ on ubuntu, I have found linking to be 
tricky with the default ABI that is compatible with GCC on ubuntu. I 
have found most advise on the net to be less than useful with 
complicated command lines that clang often interprets as errors and 
ignores -- this is a mess.  So I leave a little hint of a trick used in 
FreeBSD that works great, although it is really hacking on the ubuntu 
install it is worth it

As root rename or delete the /usr/lib/x86_64-linux-gnu/libc++.so 
symblolic link and create a file with the same name having this GROUP 
command to the linkers/loaders.

GROUP ( /usr/lib/x86_64-linux-gnu/libc++.so.1 
/usr/lib/x86_64-linux-gnu/libstdc++.so.6 )

First entry is as the symbolic link was, the second one is added 
afterwards to add the ABI from libstdc++.

Thanks to David Chisnall for his post here 
http://clang-developers.42468.n3.nabble.com/Making-libc-on-Linux-user-friendly-td4038688.html

--
Bjørn