Merge branch 'issue/optional-submodules' into 'master'

Make nanoflann an optional dependency

See merge request !29

dune/curvedgrid/test/CMakeLists.txt

@@ -20,18 +20,20 @@ dune_add_test(SOURCES discretegridviewfunctiontest.cc
                 dune-foamgrid_FOUND
                 dune-functions_FOUND)
 
-dune_add_test(SOURCES explicitsurfacetest.cc
-              COMPILE_DEFINITIONS
-                DUNE_GRID_PATH=\"${PROJECT_SOURCE_DIR}/doc/grids/\"
-              LINK_LIBRARIES
-                nanoflann::nanoflann
-              CMAKE_GUARD
-                dune-foamgrid_FOUND
-                dune-functions_FOUND)
+if(TARGET nanoflann::nanoflann)
+  dune_add_test(SOURCES explicitsurfacetest.cc
+                COMPILE_DEFINITIONS
+                  DUNE_GRID_PATH=\"${PROJECT_SOURCE_DIR}/doc/grids/\"
+                LINK_LIBRARIES
+                  nanoflann::nanoflann
+                CMAKE_GUARD
+                  dune-foamgrid_FOUND
+                  dune-functions_FOUND)
+endif()
 
 dune_add_test(SOURCES implicitsurfacetest.cc
               COMPILE_DEFINITIONS
                 DUNE_GRID_PATH=\"${PROJECT_SOURCE_DIR}/doc/grids/\"
               CMAKE_GUARD
                 dune-foamgrid_FOUND
-                dune-functions_FOUND)
\ No newline at end of file
+                dune-functions_FOUND)

libs/CMakeLists.txt

@@ -8,17 +8,15 @@ if(GIT_FOUND AND EXISTS "${PROJECT_SOURCE_DIR}/.git")
                         WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
                         RESULT_VARIABLE GIT_SUBMOD_RESULT)
         if(NOT GIT_SUBMOD_RESULT EQUAL "0")
-            message(FATAL_ERROR "git submodule update --init failed with ${GIT_SUBMOD_RESULT}, please checkout submodules")
+            message(WARNING "git submodule update --init failed with ${GIT_SUBMOD_RESULT}, please checkout submodules or set GIT_SUBMODULE=OFF")
         endif()
     endif()
 endif()
 
-if(NOT EXISTS "${PROJECT_SOURCE_DIR}/libs/nanoflann/include/nanoflann.hpp")
-    message(FATAL_ERROR "The submodules were not downloaded! GIT_SUBMODULE was turned off or failed. Please update submodules and try again.")
+if(EXISTS "${PROJECT_SOURCE_DIR}/libs/nanoflann/include/nanoflann.hpp")
+    set(DUNE_REENABLE_ADD_TEST ON)
+    set(BUILD_BENCHMARKS OFF CACHE BOOL "")
+    set(BUILD_EXAMPLES OFF CACHE BOOL "")
+    set(BUILD_TESTS OFF CACHE BOOL "")
+    add_subdirectory(nanoflann)
 endif()
-
-set(DUNE_REENABLE_ADD_TEST ON)
-set(BUILD_BENCHMARKS OFF CACHE BOOL "")
-set(BUILD_EXAMPLES OFF CACHE BOOL "")
-set(BUILD_TESTS OFF CACHE BOOL "")
-add_subdirectory(nanoflann)
\ No newline at end of file