[cfe-dev] Serious problem building LLDB to go with Clang 3.5 on Ubuntu 12.04

Fletcher, John P j.p.fletcher at aston.ac.uk
Tue Dec 31 04:57:59 PST 2013

Thank you for the quick reply.

My libc++ was built with libcxxrt and I did supply the unwind headers.  When I tried to use it  to build LLDB I had undefined references to libc++abi.  

I have then built also libc++abi and use that for the LLVM/Clang/LLDB build. I added the libc++abi to make the linkage failures go away.

The whole point of using Ubuntu 12.04 is for long term support (from Ubuntu) for stability and not having to change my operating system very often.  

The point of using clang is that it has much superior features and I can add it on top.  I don't see why it should have a dependency to gcc when I am using libc++.

This problem would be solved if LLDB did support 4.6 (unlikely from what you say although it seems to be only a few lines of code) or the linking problem could be resolved.  I think that this is the very last stage at the end of the build.

Thank you again


From: "C. Bergström" [cbergstrom at pathscale.com]
Sent: 31 December 2013 12:43
To: Fletcher, John P
Cc: clang-dev Developers
Subject: Re: [cfe-dev] Serious problem building LLDB to go with Clang 3.5 on    Ubuntu 12.04

On 12/31/13 07:35 PM, Fletcher, John P wrote:
> I should have added the commands I am running to build LLDB, which is in the LLVM tree in tools.
> export CXX=/home/fletcher/LLVM/llvm-3.5.svn/local/bin/clang++
> export CC=/home/fletcher/LLVM/llvm-3.5.svn/local/bin/clang
> export CPPFLAGS="-I/home/fletcher/LLVM/libcxxDec2013/libcxx/include -I/home/fletcher/LLVM/libcxxDec2013/libcxxabi/include -stdlib=libc++"
> export LDFLAGS="-Xlinker -R/home/fletcher/LLVM/libcxxDec2013/libcxx/lib -L/home/fletcher/LLVM/libcxxDec2013/libcxx/lib -lc++ -lc++abi"
> ../llvm/configure --prefix=/home/fletcher/LLVM/llvm-3.5.svn/local --enable-cxx11=yes --enable-optimized --enable-libcpp=yes --enable-targets=x86_64
If you're using libcxxrt you'd also need an unwind fwiw. I also don't
quite understand why adding -lc++abi.. (That doesn't make 100% sense I
think.) Skipping other issues I don't think g++-4.6 is supported
anymore. Why not install 4.8.2 or whatever? I thought there was some big
discussion on the list about gcc minimums and it was determined that was
generally available enough.

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