I am currently encountering an issue when trying to compile with clang for the first time after previously only using gcc on my Ubuntu system. I have the most minimal hello world cpp file, and try to compile with clang++ -stdlib=libstdc++ -Wall ../main.cpp -o main_clang. Note that I am using the gnu standard library that was already on my system per default I think.
With this, I get the error message:
fatal error: 'iostream' file not found
#include <iostream>
When I switch to the libc++ standard library from the llvm/clang project, I get the following error message for clang++ -stdlib=libc++ -Wall ../main.cpp -o main_clang:
/usr/bin/ld: /tmp/main-990559.o: undefined reference to symbol '__gxx_personality_v0'
/usr/bin/ld: /lib/x86_64-linux-gnu/libc++abi.so.1: error adding symbols: DSO missing from command line
clang: error: linker command failed with exit code 1 (use -v to see invocation)
I copy the verbose error message at the end of this question.
What the verbose message gives me is some paths where it searches for the header files (iostream for example). Among those you will find:
/usr/lib/llvm-14/lib/clang/14.0.0/include
/usr/local/include
/usr/include/x86_64-linux-gnu
/usr/include
I checked in those directories, and there are no or only limited header files available. Sometimes I find a bits folder or and SDL2 folder even. In the first directory from above, there are some avx512 headers and some clang_cuda files as well, which is all nice, but my actual std C++ headers are in
/usr/include/c++/11
/usr/lib/llvm-14/include/c++/v1
Can clang not find them or is the issue somewhere else?
Before someone comments this, I also tried clang++ -I /usr/include/c++/11 -stdlib=libc++ -Wall ../main.cpp -o main_clang and then I get the error: /usr/include/c++/11/iostream:38:10: fatal error: 'bits/c++config.h' file not found ... #include <bits/c++config.h>.
I have some problem with my clang installation or system setup, and I want to find it. With a clean setup, there is no/should not be the need to specify the -I flag when trying to compile with clang.
Full -v error message:
Ubuntu clang version 14.0.0-1ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/11
Found candidate GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Selected GCC installation: /usr/bin/../lib/gcc/x86_64-linux-gnu/12
Candidate multilib: .;@m64
Selected multilib: .;@m64
"/usr/lib/llvm-14/bin/clang" -cc1 -triple x86_64-pc-linux-gnu -emit-obj -mrelax-all --mrelax-relocations -disable-free -clear-ast-before-backend -disable-llvm-verifier -discard-value-names -main-file-name main.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -mllvm -treat-scalable-fixed-error-as-warning -debugger-tuning=gdb -v -fcoverage-compilation-dir=/home/ivan/Documents/TEST/build -resource-dir /usr/lib/llvm-14/lib/clang/14.0.0 -internal-isystem /usr/lib/llvm-14/bin/../include/c++/v1 -internal-isystem /usr/lib/llvm-14/lib/clang/14.0.0/include -internal-isystem /usr/local/include -internal-isystem /usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -Wall -fdeprecated-macro -fdebug-compilation-dir=/home/ivan/Documents/TEST/build -ferror-limit 19 -fgnuc-version=4.2.1 -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/main-0aa0f7.o -x c++ ../main.cpp
clang -cc1 version 14.0.0 based upon LLVM 14.0.0 default target x86_64-pc-linux-gnu
ignoring nonexistent directory "/usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/include"
#include "..." search starts here:
#include <...> search starts here:
/usr/lib/llvm-14/bin/../include/c++/v1
/usr/lib/llvm-14/lib/clang/14.0.0/include
/usr/local/include
/usr/include/x86_64-linux-gnu
/usr/include
End of search list.
"/usr/bin/ld" -pie -z relro --hash-style=gnu --build-id --eh-frame-hdr -m elf_x86_64 -dynamic-linker /lib64/ld-linux-x86-64.so.2 -o main_clang /lib/x86_64-linux-gnu/Scrt1.o /lib/x86_64-linux-gnu/crti.o /usr/bin/../lib/gcc/x86_64-linux-gnu/12/crtbeginS.o -L/usr/bin/../lib/gcc/x86_64-linux-gnu/12 -L/usr/bin/../lib/gcc/x86_64-linux-gnu/12/../../../../lib64 -L/lib/x86_64-linux-gnu -L/lib/../lib64 -L/usr/lib/x86_64-linux-gnu -L/usr/lib/../lib64 -L/usr/lib/llvm-14/bin/../lib -L/lib -L/usr/lib /tmp/main-0aa0f7.o -lc++ -lm -lgcc_s -lgcc -lc -lgcc_s -lgcc /usr/bin/../lib/gcc/x86_64-linux-gnu/12/crtendS.o /lib/x86_64-linux-gnu/crtn.o
/usr/bin/ld: /tmp/main-0aa0f7.o: undefined reference to symbol '__gxx_personality_v0'
/usr/bin/ld: /lib/x86_64-linux-gnu/libc++abi.so.1: error adding symbols: DSO missing from command line
clang: error: linker command failed with exit code 1 (use -v to see invocation)