[R-SIG-Mac] R/compilers can't find libintl.h on MacOS X

[Gavin Simpson]

Dear list

I seem to be running into a new issue after upgrading to R 4.5.0 that
seems related to this

* configure is now able to find an external libintl on macOS (the code
from an older GNU gettext distribution failed to try linking with the
macOS Core Foundation framework).

I'm pretty new to MacOS and I have installed R from homebrew, and
typically use the MacOS X binaries kindly provided by CRAN. However,
for a couple of packages I make extensive use of, I want to make use
of openMP, and so I have been following the excellent instructions on
the mac.r-project.org pages to install the relevant fortran compiler
and libomp.

Specifically, I am trying to in compile the latest mgcv sources with
openMP support. I have been doing this successfully for some time for
the 4.3 and 4.4 releases of R. But after upgrading to R 4.5.0,
compiling mgcv now throws an compilation error

In file included from magic.c:27:
./general.h:4:10: fatal error: 'libintl.h' file not found
    4 | #include <libintl.h>
      |          ^~~~~~~~~~~

(The full compile log is included below if neccessary.)

I do have gettext installed and I do have libintl.h on my system

% find /opt -name "libintl.*" -print
/opt/homebrew/include/libintl.h
/opt/homebrew/lib/libintl.dylib
/opt/homebrew/lib/libintl.8.dylib
/opt/homebrew/lib/libintl.a
/opt/homebrew/Cellar/gettext/0.24/include/libintl.h
/opt/homebrew/Cellar/gettext/0.24/lib/libintl.dylib
/opt/homebrew/Cellar/gettext/0.24/lib/libintl.8.dylib
/opt/homebrew/Cellar/gettext/0.24/lib/libintl.a

My $PATH is

% print $PATH
/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin:/opt/X11/bin:/usr/local/laps:/usr/local/munki:/usr/local/munkireport:/Applications/quarto/bin:/Users/au690221/.local/bin:/Users/au690221/.local/bin

I have edited ./src/Makevars in mgcv's sources  such that it reads

% cat ./repo/src/Makevars
PKG_LIBS =  $(LAPACK_LIBS) $(BLAS_LIBS) $(FLIBS) $(SHLIB_OPENMP_CFLAGS)
PKG_CFLAGS = $(SHLIB_OPENMP_CFLAGS)

PKG_LIBS += -lomp
PKG_CPPFLAGS = -Xclang -fopenmp
## *Both* the above must be *uncommented* for release

#PKG_CFLAGS = -g -O0 -Wall -pedantic $(SHLIB_OPENMP_CFLAGS)
## Actually it now seems that you need to reset optimization flag in
## cd /usr/local/lib/R/etc/
## sudo pico Makeconf
## This file can add flags but not modify what's in the above!
## `#' out previous line for release (but not without uncommenting openMP)

But I have tried it with the final pair of PKG_LIBS definitions that
add omp support commented out also.

My system details are

> sessionInfo()
R version 4.5.0 (2025-04-11)
Platform: aarch64-apple-darwin20
Running under: macOS Sequoia 15.4.1

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRblas.0.dylib
LAPACK: /Library/Frameworks/R.framework/Versions/4.5-arm64/Resources/lib/libRlapack.dylib;
 LAPACK version 3.12.1

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

time zone: Europe/Copenhagen
tzcode source: internal

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

loaded via a namespace (and not attached):
[1] compiler_4.5.0

and

% clang -v
Apple clang version 17.0.0 (clang-1700.0.13.3)
Target: arm64-apple-darwin24.4.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

(So I have installed LLVM 18.1.8 from https://mac.r-project.org/openmp/ )

I suspect I will need to solve this by adding the homebrew lib
location to my LD_PATH or similar, but I'm not very familiar with this
process in general and especially so on MacOS X.

I'd appreciate any help with resolving this issue.

TIA

Gavin

% R CMD INSTALL mgcv_1.9-3.tar.gz
* installing to library ‘/Users/au690221/Library/R/arm64/4.5/library’
* installing *source* package ‘mgcv’ ...
** this is package ‘mgcv’ version ‘1.9-3’
** using staged installation
** libs
using C compiler: ‘Apple clang version 17.0.0 (clang-1700.0.13.3)’
using SDK: ‘MacOSX15.4.sdk’
clang -arch arm64
-I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG
-I/opt/R/arm64/include    -fPIC  -falign-functions=64 -Wall -g -O2  -c
coxph.c -o coxph.o
clang -arch arm64
-I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG
-I/opt/R/arm64/include    -fPIC  -falign-functions=64 -Wall -g -O2  -c
davies.c -o davies.o
clang -arch arm64
-I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG
-I/opt/R/arm64/include    -fPIC  -falign-functions=64 -Wall -g -O2  -c
discrete.c -o discrete.o
clang -arch arm64
-I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG
-I/opt/R/arm64/include    -fPIC  -falign-functions=64 -Wall -g -O2  -c
gdi.c -o gdi.o
clang -arch arm64
-I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG
-I/opt/R/arm64/include    -fPIC  -falign-functions=64 -Wall -g -O2  -c
init.c -o init.o
clang -arch arm64
-I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG
-I/opt/R/arm64/include    -fPIC  -falign-functions=64 -Wall -g -O2  -c
magic.c -o magic.o
In file included from magic.c:27:
./general.h:4:10: fatal error: 'libintl.h' file not found
    4 | #include <libintl.h>
      |          ^~~~~~~~~~~
1 error generated.
make: *** [magic.o] Error 1
ERROR: compilation failed for package ‘mgcv’
* removing ‘/Users/au690221/Library/R/arm64/4.5/library/mgcv’
* restoring previous ‘/Users/au690221/Library/R/arm64/4.5/library/mgcv’
-- 
Gavin Simpson, PhD [he/him/his]
[tw] @ucfagls [OrciD] 0000-0002-9084-8413
[web] fromthebottomoftheheap.net
• Assistant Professor
• Department of Animal & Veterinary Sciences, Aarhus University
• Adjunct Professor, Department of Biology, University of Regina.