[cfe-dev] Which is the best compiler to build LLVM 5.0.0 rc2?

[don hinton via cfe-dev]

Why are you passing this?

  -DCMAKE_CXX_FLAGS="-std=c++11 -I/opt/gcc-7.1/include/c++/7.1.0"

CMakeLists.txt should take care of setting -std=c++11, and by passing
-I/opt/gcc-7.1/include/c++/7.1.0, are you short circuiting the compiler's
own include paths?




On Sat, Aug 19, 2017 at 9:00 AM, Fletcher, John P via cfe-dev <
cfe-dev at lists.llvm.org> wrote:

> Recently I have been building LLVM and Clang from the distribution using
> gcc 4.9.2.  With the new 5.0.0 rc2 that is giving warning messages during
> the compilation.  I have been trying out some other compilers.
>
> gcc 5.2 with -std=c++11   This works, although there are still some
> warnings.
>
> gcc 6.4 and gcc 7.1  fail with errors such as this in building libcxxabi
> as follows:
>
> Command: /opt/cmake/bin/cmake -G "Unix Makefiles"
> -DCMAKE_INSTALL_PREFIX=/home/fletcher/LLVM/llvm-5.0.rc2/local_71
> -DCMAKE_C_COMPILER=/opt/gcc-7.1/bin/gcc CMAKE_CXX_COMPILER=/opt/gcc-7.1/bin/g++
> -DCMAKE_BUILD_TYPE=Release -DLLVM_BUILD_LLVM_DYLIB=ON
> -DLLVM_TARGETS_TO_BUILD="host" -DCMAKE_CXX_FLAGS="-std=c++11
> -I/opt/gcc-7.1/include/c++/7.1.0" -DCMAKE_EXE_LINKER_FLAGS="-Xlinker
> -R/opt/gcc-7.1/lib64 -L/opt/gcc-7.1/lib64" ../llvm
>
> First Error:
>
> Building CXX object projects/libcxxabi/src/CMakeFiles/cxxabi_objects.dir/
> cxa_aux_runtime.cpp.o
>
> In file included from /home/fletcher/LLVM/llvm-5.0.
> rc2/llvm/projects/libcxx/include/stdlib.h:94:0,
>                  from /home/fletcher/LLVM/llvm-5.0.
> rc2/llvm/projects/libcxx/include/cstdlib:86,
>                  from /home/fletcher/LLVM/llvm-5.0.
> rc2/llvm/projects/libcxx/include/exception:82,
>                  from /home/fletcher/LLVM/llvm-5.0.
> rc2/llvm/projects/libcxx/include/new:89,
>                  from /home/fletcher/LLVM/llvm-5.0.
> rc2/llvm/projects/libcxxabi/src/cxa_aux_runtime.cpp:14:
> /opt/gcc-7.1/include/c++/7.1.0/stdlib.h:38:12: error:  std::abort  has
> not been declared
>  using std::abort;
>
> clang 4.0.0 fails with a different problem with libcxxabi -
>
> Command:
>
> /opt/cmake/bin/cmake -G "Unix Makefiles" -DCMAKE_INSTALL_PREFIX=/home/
> fletcher/LLVM/llvm-5.0.rc2/local_40 -DCMAKE_C_COMPILER=/home/
> fletcher/LLVM/llvm-4.0.distrib/local/bin/clang CMAKE_CXX_COMPILER=/home/
> fletcher/LLVM/llvm-4.0.distrib/local/bin/clang++
> -DCMAKE_BUILD_TYPE=Release -DLLVM_BUILD_LLVM_DYLIB=ON
> -DLLVM_TARGETS_TO_BUILD="host" -DCMAKE_CXX_FLAGS="-I/home/
> fletcher/LLVM/llvm-4.0.distrib/local/include/c++/v1 -stdlib=libc++"
> -DCMAKE_EXE_LINKER_FLAGS="-Xlinker -R/home/fletcher/LLVM/llvm-4.0.distrib/local/lib
> -L/home/fletcher/LLVM/llvm-4.0.distrib/local/lib -lc++abi -lclangBasic
> -lLLVMSupport -lpthread -ldl " ../llvm
>
> Error:
>
> Building CXX object projects/libcxxabi/src/CMakeFiles/cxxabi_objects.dir/
> cxa_aux_runtime.cpp.o
> In file included from /home/fletcher/LLVM/llvm-5.0.
> rc2/llvm/projects/libcxxabi/src/cxa_aux_runtime.cpp:13:
> /home/fletcher/LLVM/llvm-5.0.rc2/llvm/projects/libcxxabi/include/cxxabi.h:42:26:
> error: unknown type name
>       'size_t'
>
> It seems to me that there are some configuration problems here in getting
> the correct header arrangement.
>
> The rest of the build works, and looking around clang is recommended for
> building libcxxabi.
>
> Is this a known problem?
>
> Thanks
>
> John Fletcher
>
>
>
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>
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