[cfe-dev] Clang isn't finding C++ include dir on Ubuntu

[Robert Dailey via cfe-dev]

For completeness, here is the content of my CMake toolchain file:

set( CMAKE_SYSTEM_NAME Linux )
set( CMAKE_SYSTEM_PROCESSOR i386 )
set( CMAKE_C_COMPILER clang )
set( CMAKE_CXX_COMPILER clang++ )
set( CMAKE_C_COMPILER_ARG1 -m32 )
set( CMAKE_CXX_COMPILER_ARG1 -m32 )


On Thu, Jul 19, 2018 at 10:48 AM, Robert Dailey
<rcdailey.lists at gmail.com> wrote:
> I configured a project via CMake using clang with the -m32 option. I
> have Ubuntu 18.04 64 bit installed. I need to compile a library to 32
> bit on this platform. Based on the settings I provided to CMake, this
> is the command line it is invoking:
>
> /usr/bin/clang++ -m32   -I/home/jamesa/uri/src
> -I/home/jamesa/uri/include
> -I/home/jamesa/uri/deps/googletest/googletest/include -std=c++11
> -stdlib=libc++ -Wall -Werror -MD -MT
> test/CMakeFiles/uri_test.dir/uri_test.cpp.o -MF
> test/CMakeFiles/uri_test.dir/uri_test.cpp.o.d -o
> test/CMakeFiles/uri_test.dir/uri_test.cpp.o -c
> /home/jamesa/uri/test/uri_test.cpp
>
>
> I added the `-v` option at the end to see the system include dirs it
> is using (results will be posted at the bottom since it's rather
> long). The compilation fails because it can't find <cxxabi.h>, which
> on my install of Ubuntu is located here:
>
> $ find /usr/include/ -name cxxabi.h
> /usr/include/c++/8/cxxabi.h
> /usr/include/c++/7/cxxabi.h
>
> The path `/usr/include/c++/8` is not being added to the system include
> paths used by Clang. I'm not sure why. The complete -v output is
> below. Can anyone help me figure out what I'm missing? I have the
> `gcc-8-multilib:i386` package properly installed on my system.
>
>
> clang version 6.0.0-1ubuntu2 (tags/RELEASE_600/final)
> Target: i386-pc-linux-gnu
> Thread model: posix
> InstalledDir: /usr/bin
> Found candidate GCC installation: /usr/bin/../lib/gcc/i686-linux-gnu/8
> Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7
> Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/7.3.0
> Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8
> Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
> Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
> Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.3.0
> Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
> Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/8
> Candidate multilib: .;@m64
> Candidate multilib: 32;@m32
> Candidate multilib: x32;@mx32
> Selected multilib: 32;@m32
>  "/usr/lib/llvm-6.0/bin/clang" -cc1 -triple i386-pc-linux-gnu
> -emit-obj -mrelax-all -disable-free -disable-llvm-verifier
> -discard-value-names -main-file-name uri_test.cpp -mrelocation-model
> static -mthread-model posix -mdisable-fp-elim -fmath-errno
> -masm-verbose -mconstructor-aliases -fuse-init-array -target-cpu
> pentium4 -dwarf-column-info -debugger-tuning=gdb -v
> -coverage-notes-file
> /home/jamesa/uri_build/test/CMakeFiles/uri_test.dir/uri_test.cpp.gcno
> -resource-dir /usr/lib/llvm-6.0/lib/clang/6.0.0 -dependency-file
> test/CMakeFiles/uri_test.dir/uri_test.cpp.o.d -sys-header-deps -MT
> test/CMakeFiles/uri_test.dir/uri_test.cpp.o -I /home/jamesa/uri/src -I
> /home/jamesa/uri/include -I
> /home/jamesa/uri/deps/googletest/googletest/include -internal-isystem
> /usr/include/c++/v1 -internal-isystem
> /usr/include/clang/6.0.0/include/ -internal-isystem /usr/local/include
> -internal-isystem /usr/lib/llvm-6.0/lib/clang/6.0.0/include
> -internal-externc-isystem /usr/include/i386-linux-gnu
> -internal-externc-isystem /include -internal-externc-isystem
> /usr/include -Wall -Werror -std=c++11 -fdeprecated-macro
> -fdebug-compilation-dir /home/jamesa/uri_build -ferror-limit 19
> -fmessage-length 152 -fobjc-runtime=gcc -fcxx-exceptions -fexceptions
> -fdiagnostics-show-option -fcolor-diagnostics -o
> test/CMakeFiles/uri_test.dir/uri_test.cpp.o -x c++
> /home/jamesa/uri/test/uri_test.cpp
> clang -cc1 version 6.0.0 based upon LLVM 6.0.0 default target
> x86_64-pc-linux-gnu
> ignoring nonexistent directory "/include"
> ignoring duplicate directory "/usr/include/clang/6.0.0/include"
> #include "..." search starts here:
> #include <...> search starts here:
>  /home/jamesa/uri/src
>  /home/jamesa/uri/include
>  /home/jamesa/uri/deps/googletest/googletest/include
>  /usr/include/c++/v1
>  /usr/include/clang/6.0.0/include
>  /usr/local/include
>  /usr/include/i386-linux-gnu
>  /usr/include
> End of search list.
> In file included from /home/jamesa/uri/test/uri_test.cpp:8:
> In file included from
> /home/jamesa/uri/deps/googletest/googletest/include/gtest/gtest.h:58:
> In file included from
> /home/jamesa/uri/deps/googletest/googletest/include/gtest/internal/gtest-internal.h:66:
> /home/jamesa/uri/deps/googletest/googletest/include/gtest/internal/gtest-type-util.h:52:12:
> fatal error: 'cxxabi.h' file not found
> #  include <cxxabi.h>
>            ^~~~~~~~~~
> 1 error generated.