update cmake build for testing, build types and mixed precision

.github/workflows/github_cmake_gnu.yml

@@ -18,25 +18,17 @@ jobs:
     container:
       image: ghcr.io/noaa-gfdl/fms/fms-ci-rocky-gnu:13.2.0
       env:
-        CMAKE_FLAGS: "${{ matrix.build-type }} ${{ matrix.omp-flags }} ${{ matrix.libyaml-flag }} -D64BIT=on"
+        CMAKE_FLAGS: "${{ matrix.build-type }} ${{ matrix.omp-flags }} ${{ matrix.libyaml-flag }}"
     steps:
     - name: Checkout code
       uses: actions/[email protected]
     - name: Generate makefiles with CMake
-      run: cmake $CMAKE_FLAGS -DNetCDF_ROOT=/opt/view -DLIBYAML_ROOT=/opt/view
-    - name: Build the library
-      run: make
-    - name: Link with basic executable
       run: |
-        echo "program test" > test.F90
-        echo "    use fms_mod" >> test.F90
-        echo "    call fms_init" >> test.F90
-        echo "    call fms_end" >> test.F90
-        echo "end program" >> test.F90
-        mpifort -L/opt/view/lib -fopenmp `nf-config --flibs` -Iinclude_r4 -Iinclude_r8 test.F90 libfms_r4.a libfms_r8.a -o test.x
-        touch input.nml
-    - name: Run executable
-      run: ./test.x
+        mkdir build
+        cd build
+        cmake $CMAKE_FLAGS -DNetCDF_ROOT=/opt/view -DLIBYAML_ROOT=/opt/view ..
+    - name: Build the library
+      run: make -C build
 
   build_arm:
     runs-on: ubuntu-24.04-arm
@@ -48,22 +40,14 @@ jobs:
     container:
       image: ghcr.io/noaa-gfdl/fms/fms-ci-rocky-gnu:13.2.0-arm
       env:
-        CMAKE_FLAGS: "${{ matrix.build-type }} ${{ matrix.omp-flags }} ${{ matrix.libyaml-flag }} -D64BIT=on"
+        CMAKE_FLAGS: "${{ matrix.build-type }} ${{ matrix.omp-flags }} ${{ matrix.libyaml-flag }}"
     steps:
     - name: Checkout code
       uses: actions/[email protected]
     - name: Generate makefiles with CMake
-      run: cmake $CMAKE_FLAGS -DNetCDF_ROOT=/opt/view -DLIBYAML_ROOT=/opt/view
-    - name: Build the library
-      run: make
-    - name: Link with basic executable
       run: |
-        echo "program test" > test.F90
-        echo "    use fms_mod" >> test.F90
-        echo "    call fms_init" >> test.F90
-        echo "    call fms_end" >> test.F90
-        echo "end program" >> test.F90
-        mpifort -L/opt/view/lib -fopenmp `nf-config --flibs` -Iinclude_r4 -Iinclude_r8 test.F90 libfms_r4.a libfms_r8.a -o test.x
-        touch input.nml
-    - name: Run executable
-      run: ./test.x
+        mkdir build
+        cd build
+        cmake $CMAKE_FLAGS -DNetCDF_ROOT=/opt/view -DLIBYAML_ROOT=/opt/view ..
+    - name: Build the library
+      run: make -C build

CMAKE_INSTRUCTIONS.md

@@ -1,42 +1,55 @@
 \page cmake Building with CMake
 # Instructions for building FMS with cmake
 
-## 1. Environment Variables
+## 1. Configuring the build
 
-### For GNU compilers on Linux with the bash shell:
+### Environment Variables
 
+#### For GNU compilers on Linux with the bash shell:
 ```
 export FC=mpifort
 export CC=mpicc
 ```
-
-### For Intel Compilers on Linux with the bash shell:
-
+#### For Intel Compilers on Linux with the bash shell:
 ```
 export FC=mpiifort
 export CC=mpiicc
 ```
+MPI compiler wrappers may be named different on your system, so its best to ensure the compiler commands work prior to being set.
 
-### NetCDF is provided via the `nc-config` command:
+#### NetCDF is provided via the `nc-config` command:
 ```
 export NetCDF_ROOT=`nc-config --prefix`
 ```
 
-### If building with yaml parser (-DWITH_YAML)
+#### If building with yaml parser (-DWITH_YAML)
 ```
 export LIBYAML_ROOT=<your libyaml install directory>
 ```
 
-### Setting custom flags with the bash shell
-To override the default compiler flags:
+### Running CMake
+It's best to create a build directory inside of the FMS folder to avoid building on top of the source code.
+Once that is done, CMake can be ran to generate the necessary build files:
 ```
-export FCFLAGS="<fortran flags>"
-export CFLAGS="<c flags>"
+mkdir build && cd build
+cmake [-DWITH_YAML=on] ..
 ```
-In addition, the flag below must be included with the cmake command:
+
+### Setting a Build Type
+CMake uses "build types" to set compiler flags. By default (.ie no -DCMAKE_BUILD_TYPE="Type" argument when cmake is run), it will use the "Release" build type which corresponds the the prod/opt flags used by the GFDL mkmf templates.
+
+Similarly "Repro" and "Debug" also correspond to whatever options would be set by theircorresponding mkmf template files.
+
+To reproduce the old behavior for the cmake build (2025.03 and prior), the "ReleaseUFS" and "DebugUFS" will use the same flags as before.
+
+Please open an issue in the FMS repository if you have any issues or would like to request any changes to the current build type options.
+
+### Setting custom flags
+To override the default compiler flags, you can set them via CMake arguments:
 ```
-cmake <any other options> -DCMAKE_BUILD_TYPE=Debug ..
+cmake -DCMAKE_BUILD_TYPE="NoFlags" -DCMAKE_C_FLAGS="<c flags>" -DCMAKE_Fortran_FLAGS="<fortran flags>"
 ```
+By using the "NoFlags" build type, only necessary compilation flags will be added besides what is set via the cmake arguments.
 
 ## 2. Build and install FMS with CMake
 `<prefix>` is the full install directory for FMS provided by user
@@ -45,20 +58,25 @@ cmake <any other options> -DCMAKE_BUILD_TYPE=Debug ..
 cd FMS
 mkdir -p build && cd build
 cmake -DCMAKE_INSTALL_PREFIX=<prefix> ..
-make -j4
+make -j
 make install
 ```
 
 ### User configurable options:
-By default, FMS is built without `OpenMP`, in `single precision (r4)` and delivered in static library files.
+By default, FMS is built with `OpenMP` enabled and delivered in static library files.
+
+FMS has mixed precision real support for most interfaces. By default, one library will be created,
+`libfms`, that is compiled with r8 defaults but also contains overloaded r4 routines.
 
 The 64BIT and 32BIT precision options will build distinct libraries when enabled with the given default
-real size, libfms_r4 or libfms_r8.
+real size, libfms_r4 or libfms_r8. These option are provided for backwards compatibility, but are no longer
+supported by our development team, since mixed precision can now be used with a single library.
+Unit tests currently only work when no precision option is specified.
 
 The following build options are available:
 ```
--DOPENMP      "Build FMS with OpenMP support"        DEFAULT: OFF
--D32BIT       "Build 32-bit (r4) FMS library"        DEFAULT: ON
+-DOPENMP      "Build FMS with OpenMP support"        DEFAULT: ON
+-D32BIT       "Build 32-bit (r4) FMS library"        DEFAULT: OFF
 -D64BIT       "Build 64-bit (r8) FMS library"        DEFAULT: OFF
 -DFPIC        "Build with position independent code" DEFAULT: OFF
 -DSHARED_LIBS "Build shared/dynamic libraries"       DEFAULT: OFF
@@ -74,10 +92,10 @@ The following build options are available:
 
 ## 3. Installation structure
 
-When the above command finishes, the `<prefix>` will have an `include_r4` and a `lib` directory. The `lib ` directory will have these files:
+When the above command finishes, the `<prefix>` will have an `include` and a `lib` directory. The `lib ` directory will have these files:
 
 ```
-libfms_r4.a
+libfms.a
 cmake/fms/fms-targets.cmake
 cmake/fms/fms-targets-release.cmake
 cmake/fms/fms-config.cmake