llvm dev - Jun 2016 - [cfe-dev] clang++ build from source is not able to find C++ headers

On Thu, Jun 23, 2016 at 7:36 PM, Tim Northover <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> 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 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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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.


Jon
> 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.
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-- 
Jon Roelofs
jonathan at codesourcery.com
CodeSourcery / Mentor Embedded

Hi Vivek,

you can also include these lines below to your ~/.bash_profile:

LLVM_BUILD="/Developer/llvm/build" # Path to your build directory

alias new-clang="$LLVM_BUILD/bin/clang -Wno-expansion-to-defined
-I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include"
alias new-clang++="$LLVM_BUILD/bin/clang++ -Wno-expansion-to-defined
-I/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk/usr/include/c++"


where you only need to set LLVM_BUILD to where in you system you built
llvm/clang.

After that, invoke "source ~/.bash_profile" on the current terminal,
or
simply open a new terminal, and you'll be able to use new-clang and
new-clang++, instead of clang and clang++, to invoke your newest compiled
binary.


--
Cristianno Martins
PhD Student of Computer Science
University of Campinas
cmartins at ic.unicamp.br
<cristiannomartins at hotmail.com>

On Thu, Jun 23, 2016 at 2:58 PM, Jonathan Roelofs via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
>
>
> 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.
>
>
> Jon
>
> 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.
>>
>>
>>
>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>>
> --
> Jon Roelofs
> jonathan at codesourcery.com
> CodeSourcery / Mentor Embedded
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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