Fix CMake circular dependencies for external use

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add explicit `find_package()` calls for missing dependencies for MAPL for builds with spack-stack. Will eventually be fixed in MAPL in later versions
 - Corrected the units of the gravimetric soil moisture to percent instead of fractional in the FENGSHA dust scheme.
+- Fix issue of GOCART/GEOSgcm circular CMake dependencies when used as external project
 
 ### Added
 

CMakeLists.txt

@@ -2,24 +2,42 @@ cmake_minimum_required (VERSION 3.17)
 cmake_policy (SET CMP0053 NEW)
 cmake_policy (SET CMP0054 NEW)
 
-project (
-        GOCART
-        VERSION 2.2.1
-        LANGUAGES Fortran CXX C)  # Note - CXX is required for ESMF
-
-if ("${PROJECT_SOURCE_DIR}" STREQUAL "${PROJECT_BINARY_DIR}")
-    message(SEND_ERROR "In-source builds are disabled. Please
-           issue cmake command in separate build directory.")
-endif ("${PROJECT_SOURCE_DIR}" STREQUAL "${PROJECT_BINARY_DIR}")
-
-# Set the default build type to release
-if (NOT CMAKE_BUILD_TYPE)
-    message (STATUS "Setting build type to 'Release' as none was specified.")
-    set (CMAKE_BUILD_TYPE Release CACHE STRING "Choose the type of build." FORCE)
-    # Set the possible values of build type for cmake-gui
-    set_property (CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
-            "Debug" "Release" "MinSizeRel" "RelWithDebInfo")
-endif ()
+# Let's look for the ESMA cmake directory in a few places
+# to see if we are building standalone
+set (ESMA_CMAKE_DIRS
+  cmake
+  @cmake
+  cmake@
+  )
+
+foreach (dir IN LISTS ESMA_CMAKE_DIRS)
+  if (EXISTS ${CMAKE_CURRENT_LIST_DIR}/${dir})
+    list (APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/${dir}")
+    set (ESMA_CMAKE_PATH "${CMAKE_CURRENT_LIST_DIR}/${dir}" CACHE PATH "Path to ESMA_cmake code")
+    set(GOCART_STANDALONE TRUE)
+  endif ()
+endforeach ()
+
+if (GOCART_STANDALONE)
+  project (
+          GOCART
+          VERSION 2.2.1
+          LANGUAGES Fortran CXX C)  # Note - CXX is required for ESMF
+
+  if ("${PROJECT_SOURCE_DIR}" STREQUAL "${PROJECT_BINARY_DIR}")
+      message(SEND_ERROR "In-source builds are disabled. Please
+            issue cmake command in separate build directory.")
+  endif ("${PROJECT_SOURCE_DIR}" STREQUAL "${PROJECT_BINARY_DIR}")
+
+  # Set the default build type to release
+  if (NOT CMAKE_BUILD_TYPE)
+      message (STATUS "Setting build type to 'Release' as none was specified.")
+      set (CMAKE_BUILD_TYPE Release CACHE STRING "Choose the type of build." FORCE)
+      # Set the possible values of build type for cmake-gui
+      set_property (CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS
+              "Debug" "Release" "MinSizeRel" "RelWithDebInfo")
+  endif ()
+endif()
 
 # Set build options
 option (UFS_GOCART "Build GOCART component for UFS" OFF)
@@ -41,11 +59,12 @@ if (UFS_GOCART)
 endif()
 
 if (NOT COMMAND esma)
-    list (APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake@")
     include (esma)
 endif()
 
-ecbuild_declare_project()
+if(GOCART_STANDALONE)
+  ecbuild_declare_project()
+endif()
 
 if (NOT Baselibs_FOUND)
   # Find dependencies
@@ -87,7 +106,9 @@ include_directories(${MPI_Fortran_INCLUDE_PATH})
 add_subdirectory (ESMF)
 add_subdirectory (Process_Library)
 
-ecbuild_install_project (NAME GOCART)
+if(GOCART_STANDALONE)
+  ecbuild_install_project (NAME GOCART)
+endif()
 
 # https://www.scivision.dev/cmake-auto-gitignore-build-dir/
 # --- auto-ignore build directory

ESMF/Shared/CMakeLists.txt

@@ -12,10 +12,12 @@ if( EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/@GSW )
     set (gsw_ECBUILD_SYSTEM_INCLUDED TRUE)
 endif()
 
-if ( IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/MAPL@ )
-  esma_add_subdirectories (
-    MAPL
-    )
+if (NOT TARGET MAPL)
+  if ( IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/MAPL@ )
+    esma_add_subdirectories (
+      MAPL
+      )
+  endif ()
 endif ()
 
 if ( IS_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}/GMAO_Shared@ )