[R] data.table does not find openmp support

[Naresh Gurbuxani]

On my Intel Mac, with R 4.4, data.table worked with openmp support.
After installing R 4.5, I reinstalled data.table using
install.packages("data.table").  Installation went smoothly, but
data.table did not detect openmp support.  I removed data.table, then
reinstalled using install.packages("data.table", type = "source").  Now
data.table install has non-zero exit status.

Following instructions at https://mac.r-project.org/openmp/, I installed
Open MP support by running on command line

curl -O https://mac.r-project.org/openmp/openmp-17.0.6-darwin20-Release.tar.gz
sudo tar fvxz openmp-17.0.6-darwin20-Release.tar.gz -C /

Below is information from my R session:

> sessionInfo()
R version 4.5.2 (2025-10-31)
Platform: x86_64-apple-darwin20
Running under: macOS Sequoia 15.7.3

Matrix products: default
BLAS:   /Library/Frameworks/R.framework/Versions/4.5-x86_64/Resources/lib/libRblas.0.dylib 
LAPACK: /Library/Frameworks/R.framework/Versions/4.5-x86_64/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: America/New_York
tzcode source: internal

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

other attached packages:
[1] lattice_0.22-7

loaded via a namespace (and not attached):
[1] compiler_4.5.2 tools_4.5.2    grid_4.5.2    
> system("gfortran --version")
GNU Fortran (GCC) 14.2.0
Copyright (C) 2024 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
> system("xcode-select -version")
xcode-select version 2410.
> system("gcc --version")
Apple clang version 17.0.0 (clang-1700.6.3.2)
Target: x86_64-apple-darwin24.6.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin
> install.packages("data.table", lib = .libPaths()[2], type = "source")
trying URL 'https://cran.r-project.org/src/contrib/data.table_1.18.0.tar.gz'
Content type 'application/x-gzip' length 6020932 bytes (5.7 MB)
==================================================
downloaded 5.7 MB

* installing *source* package ‘data.table’ ...
** this is package ‘data.table’ version ‘1.18.0’
** package ‘data.table’ successfully unpacked and MD5 sums checked
** using staged installation
zlib 1.3.1 is available ok
* checking if R installation supports OpenMP with "-Xclang -fopenmp" ... yes
** libs
using C compiler: ‘Apple clang version 17.0.0 (clang-1700.6.3.2)’
using SDK: ‘MacOSX26.2.sdk’
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c assign.c -o assign.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c between.c -o between.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c bmerge.c -o bmerge.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c chmatch.c -o chmatch.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c cj.c -o cj.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c coalesce.c -o coalesce.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c dogroups.c -o dogroups.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c fastmean.c -o fastmean.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c fcast.c -o fcast.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c fifelse.c -o fifelse.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c fmelt.c -o fmelt.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c forder.c -o forder.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c frank.c -o frank.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c fread.c -o fread.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c freadR.c -o freadR.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c froll.c -o froll.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c frollR.c -o frollR.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c frolladaptive.c -o frolladaptive.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c frollapply.c -o frollapply.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c fsort.c -o fsort.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c fwrite.c -o fwrite.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c fwriteR.c -o fwriteR.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c gsumm.c -o gsumm.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c hash.c -o hash.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c idatetime.c -o idatetime.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c ijoin.c -o ijoin.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c init.c -o init.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c inrange.c -o inrange.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c mergelist.c -o mergelist.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c nafill.c -o nafill.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c negate.c -o negate.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c nqrecreateindices.c -o nqrecreateindices.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c openmp-utils.c -o openmp-utils.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c programming.c -o programming.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c quickselect.c -o quickselect.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c rbindlist.c -o rbindlist.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c reorder.c -o reorder.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c shellsort.c -o shellsort.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c shift.c -o shift.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c snprintf.c -o snprintf.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c subset.c -o subset.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c transpose.c -o transpose.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c types.c -o types.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c uniqlist.c -o uniqlist.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c utils.c -o utils.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c vecseq.c -o vecseq.o
clang -arch x86_64 -I"/Library/Frameworks/R.framework/Resources/include" -DNDEBUG   -I/opt/R/x86_64/include   -Xclang -fopenmp  -I/opt/local/include -fPIC  -falign-functions=64 -Wall -g -O2  -c wrappers.c -o wrappers.o
clang -arch x86_64 -dynamiclib -Wl,-headerpad_max_install_names -undefined dynamic_lookup -L/Library/Frameworks/R.framework/Resources/lib -L/opt/R/x86_64/lib -o data.table.so assign.o between.o bmerge.o chmatch.o cj.o coalesce.o dogroups.o fastmean.o fcast.o fifelse.o fmelt.o forder.o frank.o fread.o freadR.o froll.o frollR.o frolladaptive.o frollapply.o fsort.o fwrite.o fwriteR.o gsumm.o hash.o idatetime.o ijoin.o init.o inrange.o mergelist.o nafill.o negate.o nqrecreateindices.o openmp-utils.o programming.o quickselect.o rbindlist.o reorder.o shellsort.o shift.o snprintf.o subset.o transpose.o types.o uniqlist.o utils.o vecseq.o wrappers.o -lomp -L/opt/local/lib -lz -F/Library/Frameworks/R.framework/.. -framework R
PKG_CFLAGS = -Xclang -fopenmp -I/opt/local/include
PKG_LIBS = -lomp -L/opt/local/lib -lz
if [ "data.table.so" != "data_table.so" ]; then mv data.table.so data_table.so; fi
if [ "" != "Windows_NT" ] && [ `uname -s` = 'Darwin' ]; then install_name_tool -id data_table.so data_table.so; fi
installing to /Library/Frameworks/R.framework/Versions/4.5-x86_64/Resources/library/00LOCK-data.table/00new/data.table/libs
** R
** inst
** byte-compile and prepare package for lazy loading
** help
*** installing help indices
** building package indices
** installing vignettes
** testing if installed package can be loaded from temporary location
Error: package or namespace load failed for ‘data.table’ in dyn.load(file, DLLpath = DLLpath, ...):
unable to load shared object '/Library/Frameworks/R.framework/Versions/4.5-x86_64/Resources/library/00LOCK-data.table/00new/data.table/libs/data_table.so':
  dlopen(/Library/Frameworks/R.framework/Versions/4.5-x86_64/Resources/library/00LOCK-data.table/00new/data.table/libs/data_table.so, 0x0006): symbol not found in flat namespace '___kmpc_dispatch_deinit'
Error: loading failed
Execution halted
ERROR: loading failed
* removing ‘/Library/Frameworks/R.framework/Versions/4.5-x86_64/Resources/library/data.table’

The downloaded source packages are in
	‘/private/var/folders/d5/sbs6108j6qd9jw7g652bm9sr0000gn/T/RtmpqcFVH3/downloaded_packages’
Warning message:
In install.packages("data.table", lib = .libPaths()[2], type = "source") :
  installation of package ‘data.table’ had non-zero exit status