Under macOS explicitly install and configure OpenMP support

Author: eddelbuettel

.github/workflows/ci.yaml

@@ -31,6 +31,17 @@ jobs:
         with:
           dev_version: 'TRUE'
 
+      - name: OpenMP for macOS
+        if: ${{ matrix.os == 'macos-latest' }}
+        run: |
+          curl -fsSL https://raw.githubusercontent.com/coatless-shell/openmp/main/install-openmp.sh | bash -s -- --yes
+          mkdir -p ~/.R
+          cat <<EOF > ~/.R/Makevars
+          CPPFLAGS += -Xclang -fopenmp
+          LDFLAGS += -lomp
+          EOF
+          cat ~/.R/Makevars
+
       - name: Configure
         run: ./configure; cat src/Makevars
 

ChangeLog

@@ -9,6 +9,10 @@
 
 	* inst/tinytest/test_Rlapack.R: Skip this test involving complex
 	algebra if on macOS as the LAPACK switch by R affects it
+2025-11-19  Dirk Eddelbuettel  <[email protected]>
+
+	* .github/workflows/ci.yaml (jobs): On macOS, explicitly install and
+	configure OpenMP
 
 2025-11-13  Dirk Eddelbuettel  <[email protected]>