Add mpi testing to GitHub workflow

.github/workflows/ci.yml

@@ -23,11 +23,11 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest]
-        compiler: [intel, gnu]
+        compiler: [gnu, intel]
+        interface: [serial, mpi]
         exclude:
-          # MacOS has no Intel compiler
-          - os: macos-latest
-            compiler: intel
+        - os: macos-latest
+          compiler: intel
 
     steps:
 
@@ -38,9 +38,10 @@ jobs:
         if: ${{ contains(matrix.compiler, 'intel') }}
         uses: rscohn2/setup-oneapi@v0
         with:
-          # Note: intel 2024.1 and 2024.2 fail to build Fortuno properly due to a compiler bug,
-          # see https://community.intel.com/t5/Intel-Fortran-Compiler/Compiler-bug-Procedure-pointer-association-status-gets-lost/m-p/1612121#M172850
-          components: [email protected]
+          components: |
+            ifx
+            icx
+            impi
 
       - name: Setup Intel environment
         if: ${{ contains(matrix.compiler, 'intel') }}
@@ -49,6 +50,9 @@ jobs:
           printenv >> ${GITHUB_ENV}
           echo "FC=ifx" >> ${GITHUB_ENV}
           echo "FPM_FC=ifx" >> ${GITHUB_ENV}
+          # Overriding default FPM_FFLAGS as default setting contains '-standard-semantics'
+          # which is incompatible with intel MPI.
+          echo "FPM_FFLAGS='-warn all -check all,nouninit -error-limit 1 -O0 -g -stand f18 -traceback'" >> ${GITHUB_ENV}
 
       - name: Setup GNU compiler
         if: ${{ contains(matrix.compiler, 'gnu') }}
@@ -63,13 +67,38 @@ jobs:
           echo "FC=${{ env.FC }}" >> ${GITHUB_ENV}
           echo "FPM_FC=${{ env.FC }}" >> ${GITHUB_ENV}
 
+      - name: Setup MPI on Ubuntu
+        if: ${{ contains(matrix.os, 'ubuntu') && contains(matrix.interface, 'mpi') }}
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y mpich
+
+      - name: Setup MPI on MacOS
+        if: ${{ contains(matrix.os, 'macos') && contains(matrix.interface, 'mpi') }}
+        run: |
+          brew install openmpi
+
+      - name: Setup serial interface options
+        if: ${{ contains(matrix.interface, 'serial') }}
+        run: |
+          echo "CMAKE_OPTIONS=-DFORTUNO_BUILD_SERIAL_INTERFACE=ON -DFORTUNO_BUILD_MPI_INTERFACE=OFF" >> ${GITHUB_ENV}
+          echo "MESON_OPTIONS=-Dbuild_serial_interface=true -Dbuild_mpi_interface=false" >> ${GITHUB_ENV}
+          echo "INTERFACE=serial" >> ${GITHUB_ENV}
+
+      - name: Setup mpi interface options
+        if: ${{ contains(matrix.interface, 'mpi') }}
+        run: |
+          echo "CMAKE_OPTIONS=-DFORTUNO_BUILD_SERIAL_INTERFACE=OFF -DFORTUNO_BUILD_MPI_INTERFACE=ON" >> ${GITHUB_ENV}
+          echo "MESON_OPTIONS='-Dbuild_serial_interface=false -Dbuild_mpi_interface=true'" >> ${GITHUB_ENV}
+          echo "INTERFACE=mpi" >> ${GITHUB_ENV}
+
       - name: Setup build tools
         run: |
           pip install cmake fpm meson ninja fypp
 
       - name: Build Fortuno with CMake
         run: |
-          cmake -DCMAKE_INSTALL_PREFIX=${INSTALL_DIR} -B ${BUILD_DIR} -G Ninja
+          cmake ${CMAKE_OPTIONS} -DCMAKE_INSTALL_PREFIX=${INSTALL_DIR} -B ${BUILD_DIR} -G Ninja
           cmake --build ${BUILD_DIR}
           cmake --install ${BUILD_DIR}
           rm -rf ${BUILD_DIR}
@@ -81,13 +110,13 @@ jobs:
 
       - name: Build Fortuno with Meson
         run: |
-          meson setup -Dbuild_examples=true ${BUILD_DIR}
+          meson setup ${MESON_OPTIONS} -Dbuild_examples=true ${BUILD_DIR}
           ninja -C ${BUILD_DIR}
           rm -rf ${BUILD_DIR}
 
       - name: Test CMake export
         run: |
-          CMAKE_PREFIX_PATH=${INSTALL_DIR} cmake -B ${BUILD_DIR} -G Ninja test/export/serial
+          CMAKE_PREFIX_PATH=${INSTALL_DIR} cmake -B ${BUILD_DIR} -G Ninja test/export/${INTERFACE}
           cmake --build ${BUILD_DIR}
           ${BUILD_DIR}/app/testapp
           ${BUILD_DIR}/app/testapp_fypp
@@ -101,7 +130,7 @@ jobs:
       - name: Test Meson pkgconfig export
         run: |
           export PKG_CONFIG_PATH="${PWD}/${INSTALL_DIR}/lib/pkgconfig:${PKG_CONFIG_PATH}"
-          cd test/export/serial
+          cd test/export/${INTERFACE}
           meson setup --wrap-mode nofallback ${BUILD_DIR}
           ninja -C ${BUILD_DIR}
           ${BUILD_DIR}/testapp
@@ -111,7 +140,7 @@ jobs:
         run: |
           FORTUNO_DIR=${PWD}
           GIT_REV=$(git rev-parse HEAD)
-          cd test/export/serial
+          cd test/export/${INTERFACE}
           mkdir subprojects
           echo -e "[wrap-git]\ndirectory=fortuno\n" > subprojects/fortuno.wrap
           echo -e "url=file://${FORTUNO_DIR}\nrevision=${GIT_REV}\n" >> subprojects/fortuno.wrap