Unable to install R packages due to library not found

Question

In any R package I try to install, I get the following error message:

ld: library not found for -lintl
collect2: error: ld returned 1 exit status
make: *** [utf8.so] Error 1

I'm not sure how to make this a reprex, but I am running: R version 4.0.2 (2020-06-22) Platform: x86_64-apple-darwin19.5.0 (64-bit) Running under: macOS Catalina 10.15.5

What does this error message (ld: library not found for -lintl) mean and how can I fix it to be able to install R packages (the packages I have tried are texreg and lme4)? Thank you.

Edit: I apologize, I thought I had included this with my post. I am not missing gettext (as per Link error installing Rcpp "library not found for -lintl"), and I followed the instructions to export the LPDFLAGS and CPPFLAGS so that they are linked.

As best I can tell, the problem is the ~/.R/Makevars file, which currently looks like this, where I've commented out things I've added to it based on googling.

CC=/usr/local/Cellar/gcc/9.3.0_1/bin/gcc-9
CXX=/usr/local/Cellar/gcc/9.3.0_1/bin/g++-9
CXX11=/usr/local/Cellar/gcc/9.3.0_1/bin/g++-9
CXX14=/usr/local/Cellar/gcc/9.3.0_1/bin/g++-9
cxx17=/usr/local/cellar/gcc/9.3.0_1/bin/g++-9
cxx1X=/usr/local/cellar/gcc/9.3.0_1/bin/g++-9
LDFLAGS=-L/usr/local/Cellar/gcc/9.3.0_1/lib
#FLIBS=-L/usr/local/gfortran/lib/gcc/x86_64-apple-darwin18/8.2.0

#CC=/usr/local/clang4/bin/clang
#CXX=/usr/local/clang4/bin/clang++
#CXX1X=/usr/local/clang4/bin/clang++
#CXX98=/usr/local/clang4/bin/clang++
#CXX11=/usr/local/clang4/bin/clang++
#CXX14=/usr/local/clang4/bin/clang++
#CXX17=/usr/local/clang4/bin/clang++
#LDFLAGS=-L/usr/local/clang4/lib

Answer 1

Apparently, I needed to remove all the lines from ~/.R/Makevars and I was able to install lme4. I did get some warnings, but library(lme4) works.

Answer 2

If you're using a mac with an Apple Silicon chip (like the M1), then you can try adding this to ~/.R/Makevars:

CFLAGS=-I/opt/homebrew/include
CPPFLAGS=-I/opt/homebrew/include
CXXFLAGS=-I/opt/homebrew/include
CXX11FLAGS=-I/opt/homebrew/include
LDFLAGS=-L/opt/homebrew/lib

This allows R to find the needed libraries. You will need to first ensure you have the needed compilers and dependencies installed. You can usually do this with brew.