Add deal.II as an optional dependency

Author: sebproell

CMakeLists.txt

@@ -120,6 +120,7 @@ four_c_configure_dependency(HDF5 DEFAULT ON)
 four_c_configure_dependency(MPI DEFAULT ON)
 four_c_configure_dependency(Qhull DEFAULT ON)
 four_c_configure_dependency(Trilinos DEFAULT ON)
+four_c_configure_dependency(deal.II DEFAULT OFF)
 four_c_configure_dependency(Boost DEFAULT ON)
 four_c_configure_dependency(ArborX DEFAULT OFF)
 four_c_configure_dependency(FFTW DEFAULT ON)

cmake/configure/configure_deal.II.cmake

@@ -0,0 +1,37 @@
+# This file is part of 4C multiphysics licensed under the
+# GNU Lesser General Public License v3.0 or later.
+#
+# See the LICENSE.md file in the top-level for license information.
+#
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
+# At this point we deliberately turned on the option to use deal.II, so fail if it is not available.
+find_package(deal.II REQUIRED)
+
+if(NOT DEAL_II_WITH_TRILINOS)
+  message(
+    FATAL_ERROR
+      "deal.II was not compiled with Trilinos support. Please recompile deal.II with Trilinos support."
+    )
+endif()
+
+# N.B. We do NOT use dealii::dealii here, since this pulls in a lot of flags that we might not want.
+# Instead, deal.II potentially provides two targets: dealii::dealii_release and/or dealii::dealii_debug.
+if(TARGET dealii::dealii_release)
+  message(STATUS "Using target dealii::dealii_release")
+  target_link_libraries(four_c_all_enabled_external_dependencies INTERFACE dealii::dealii_release)
+elseif(TARGET dealii::dealii_debug)
+  message(STATUS "Using target dealii::dealii_debug")
+  target_link_libraries(four_c_all_enabled_external_dependencies INTERFACE dealii::dealii_debug)
+else()
+  message(FATAL_ERROR "Could not find target dealii::dealii_release or dealii::dealii_debug.")
+endif()
+
+include(${DEAL_II_GIT_CONFIG})
+set(FOUR_C_deal.II_GIT_HASH "${DEAL_II_GIT_REVISION}")
+
+configure_file(
+  "${PROJECT_SOURCE_DIR}/cmake/templates/deal.II.cmake.in"
+  "${PROJECT_BINARY_DIR}/cmake/templates/deal.II.cmake"
+  @ONLY
+  )

cmake/setup_install.cmake

@@ -73,6 +73,7 @@ _add_dependency_to_settings(HDF5)
 _add_dependency_to_settings(MPI)
 _add_dependency_to_settings(Qhull)
 _add_dependency_to_settings(Trilinos)
+_add_dependency_to_settings(deal.II)
 _add_dependency_to_settings(Boost)
 _add_dependency_to_settings(ArborX)
 _add_dependency_to_settings(FFTW)

cmake/templates/4CConfig.cmake.in

@@ -27,6 +27,10 @@ if(FOUR_C_WITH_TRILINOS)
   endif()
 endif()
 
+if(FOUR_C_WITH_DEAL_II)
+  find_package(deal.II REQUIRED CONFIG HINTS ${FOUR_C_DEAL_II_ROOT})
+endif()
+
 if(FOUR_C_WITH_BOOST)
   find_package(
     Boost

cmake/templates/4CSettings.cmake.in

@@ -9,6 +9,7 @@ set(FOUR_C_WITH_HDF5 @FOUR_C_WITH_HDF5@)
 set(FOUR_C_WITH_MPI @FOUR_C_WITH_MPI@)
 set(FOUR_C_WITH_QHULL @FOUR_C_WITH_QHULL@)
 set(FOUR_C_WITH_TRILINOS @FOUR_C_WITH_TRILINOS@)
+set(FOUR_C_WITH_DEAL_II @FOUR_C_WITH_DEAL_II@)
 set(FOUR_C_WITH_BOOST @FOUR_C_WITH_BOOST@)
 set(FOUR_C_WITH_ARBORX @FOUR_C_WITH_ARBORX@)
 set(FOUR_C_WITH_FFTW @FOUR_C_WITH_FFTW@)

cmake/templates/deal.II.cmake.in

@@ -0,0 +1 @@
+set(FOUR_C_DEAL_II_ROOT "@FOUR_C_DEAL_II_ROOT@")

dependencies/supported_version/deal.II.txt

@@ -0,0 +1 @@
+6890ca740b6e51530ebb7ae7e4932977010ef2be 2025.1 v9.6.2