[llvm-dev] [cfe-dev] clang++ build from source is not able to find C++ headers

Jonathan Roelofs via llvm-dev llvm-dev at lists.llvm.org
Thu Jun 23 10:58:38 PDT 2016

On 6/23/16 11:56 AM, vivek pandya via llvm-dev wrote:
> On Thu, Jun 23, 2016 at 7:36 PM, Tim Northover <t.p.northover at gmail.com
> <mailto:t.p.northover at gmail.com>> wrote:
>     On 23 June 2016 at 06:31, vivek pandya via cfe-dev
>     <cfe-dev at lists.llvm.org <mailto:cfe-dev at lists.llvm.org>> wrote:
>     > I am running OS X, when I build clang++ from source and use it to compile
>     > .cpp files it fails as it is not able to find C++ header. I am not building
>     > libc++ along with llvm and clang.
>     When I'm not building with libcxx in-tree I find it easiest to just
>     symlink Xcode's libc++ headers into the build directory. Something
>     like "ln -s
>     /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/include/c++
>     build/include".
> Thanks Tim,
> symlink to build include does not help because clang++ looks headers
> into build/lib/clang/3.9.0/include ( as per output of clang++ -v) but I

That path is where clang is looking for compiler-provided headers. You 
should see another path in the -v output that says where it is looking 
for the c++ headers, which should not be in the same place.


> symlink to /usr/local/include , that worked I hope there is nothing
> wrong in doing so.
> -Vivek
>     > using -stdlib=libstdc++ solves problem partially but it fails when using
>     > C++11 threads, again it can't find <thread>, to get this work clang++ should
>     > work with -stdlib=libc++ but it fails with previous error of not finding C++
>     > headers.
>     Yes, the libstdc++ included with OS X is ancient (from GCC 4.2 I
>     think) and there only for compatibility reasons. It has virtually no
>     support for C++11, which LLVM needs.
>     Cheers.
>     Tim.
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Jon Roelofs
jonathan at codesourcery.com
CodeSourcery / Mentor Embedded

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