llvm built with system gcc missing gcc-toolchain #16689
Description
I'd like to use the system gcc and spack install llvm.
However, the built clang/clang++ cannot build codes because of missing gcc-toolchain configuration.
Steps to reproduce the issue
$ spack install llvm
$ module load llvm-10.0.0-gcc-9.3.0-brezhrw
$ clang++ -std=c++11 -g -O3 -fopenmp -o gemv-omp.cpp.x -I ../../common gemv-omp.cpp
/usr/bin/ld: cannot find crtbegin.o: No such file or directory
clang-10: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [Makefile:19: gemv-omp.cpp.x] Error 1
$ # Now add --gcc-toolchain=/usr works
$ clang++ --gcc-toolchain=/usr -std=c++11 -g -O3 -fopenmp -o gemv-omp.cpp.x -I ../../common gemv-omp.cpp
$Information on your system
Ubuntu 20.04 with gcc 9.3
Additional information
- I have searched the issues of this repo and believe this is not a duplicate
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