I'm trying to install a package in R, and I get the following error:
clang: error: unsupported option '-fopenmp'
This, is after I got an error:
ld: warning: search path '/opt/gfortran/lib/gcc/aarch64-apple-darwin20.0/12.2.0' not found
ld: warning: search path '/opt/gfortran/lib' not found
ld: library 'gfortran' not found
From my understanding this is an issue of the compiler. So I edited .R/Makevars to point towards the correct compiler (GCC). If I understand correctly, it should support OpenMP. This is currently my Makevars file:
# This file's location is ~/.R/Makevars
# Default variables (no omp)
# Also potentially CXX11 (for C++11 compiler)
# CXX11=/usr/bin/clang++
# I followed the instructions at http://hpc.sourceforge.net/ to install gcc 4.9
CC=/opt/homebrew/bin/gcc-14
CXX=/opt/homebrew/bin/gcc-14
FC=/opt/homebrew/bin/gfortran
F77=/opt/homebrew/bin/gfortran
PKG_LIBS = -fopenmp -lgomp
PKG_CFLAGS= -O3 -Wall -pipe -pedantic -std=gnu99 -fopenmp
CFLAGS= -O3 -Wall -pipe -pedantic -std=gnu99 -fopenmp
SHLIB_OPENMP_CFLAGS=-Xpreprocessor -fopenmp
SHLIB_OPENMP_CXXFLAGS=-Xpreprocessor -fopenmp
I've seen some other questions about the topic, but they were either directly related to data.table package. Or they didn't solve the issue.
What worked for me is setting the compiler paths directly:
# This file's location is ~/.R/Makevars
# Default variables (no omp)
CC=/opt/homebrew/bin/gcc-14
CXX=/opt/homebrew/bin/gcc-14
FC=/opt/homebrew/bin/gfortran
F77=/opt/homebrew/bin/gfortran
FLIBS=-L/opt/homebrew/opt/gcc/lib/gcc/14
Not sure if it has openMP support or not, but it allowed me to compile the package.