From 7ccf207c33fc7d61e2941a0f567be95eeb4c68af Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jean-No=C3=ABl=20Grad?= <jgrad@icp.uni-stuttgart.de>
Date: Mon, 24 Feb 2025 13:01:36 +0100
Subject: [PATCH] Add support for CMake 4.0

---
 CMakeLists.txt                   | 45 ++++++++++++++++----------------
 cmake/FindCUDACompilerNVCC.cmake | 13 ---------
 cmake/walberla.patch             |  6 +++++
 3 files changed, 29 insertions(+), 35 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index ed63501d311..d025b80660f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,14 +21,6 @@
 
 cmake_minimum_required(VERSION 3.25.1)
 cmake_policy(VERSION 3.25.1)
-if(POLICY CMP0167)
-  # use BoostConfig.cmake shipped with Boost 1.70+ instead of the one in CMake
-  cmake_policy(SET CMP0167 NEW)
-endif()
-if(POLICY CMP0169)
-  # use deprecated FetchContent_Populate function for h5xx dependency
-  cmake_policy(SET CMP0169 OLD)
-endif()
 message(STATUS "CMake version: ${CMAKE_VERSION}")
 # CMake modules/macros are in a subdirectory to keep this file cleaner
 set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
@@ -64,6 +56,7 @@ endif()
 
 include(FeatureSummary)
 include(GNUInstallDirs)
+include(ExternalProject)
 include(FetchContent)
 include(espresso_option_enum)
 include(espresso_enable_avx2_support)
@@ -114,11 +107,6 @@ FetchContent_Declare(
   GIT_REPOSITORY https://github.com/hmenke/espresso-stokesian-dynamics.git
   GIT_TAG        90f6de70d1c0ac9cf468f2fc90f9c601139e4c88
 )
-FetchContent_Declare(
-  h5xx
-  GIT_REPOSITORY https://github.com/h5md/h5xx.git
-  GIT_TAG        0.9.1
-)
 FetchContent_Declare(
   caliper
   GIT_REPOSITORY https://github.com/LLNL/Caliper.git
@@ -509,19 +497,27 @@ if(ESPRESSO_BUILD_WITH_HDF5)
       )
     endif()
   endif()
-  # We need to define our own h5xx target, since the project version we depend
-  # on is not fully compatible with modern CMake.
-  FetchContent_GetProperties(h5xx)
-  if(NOT h5xx_POPULATED)
-    FetchContent_Populate(h5xx)
-  endif()
-  add_library(h5xx INTERFACE)
   add_library(hdf5 INTERFACE)
   target_link_libraries(hdf5 INTERFACE $<BUILD_INTERFACE:${HDF5_LIBRARIES}>)
   target_include_directories(hdf5
                              INTERFACE $<BUILD_INTERFACE:${HDF5_INCLUDE_DIRS}>)
-  target_include_directories(h5xx
-                             INTERFACE $<BUILD_INTERFACE:${h5xx_SOURCE_DIR}>)
+  # We need to define our own h5xx target, since the project version we depend
+  # on is not fully compatible with modern CMake.
+  add_library(h5xx INTERFACE)
+  # cmake-format: off
+  ExternalProject_Add(
+    h5xx_library
+    GIT_REPOSITORY    https://github.com/h5md/h5xx.git
+    GIT_TAG           0.9.1
+    PREFIX            lib_h5xx
+    # header-only library: disable configuration/build/install steps
+    CONFIGURE_COMMAND ""
+    BUILD_COMMAND     ""
+    INSTALL_COMMAND   ""
+  )
+  # cmake-format: on
+  ExternalProject_Get_Property(h5xx_library SOURCE_DIR)
+  target_include_directories(h5xx INTERFACE $<BUILD_INTERFACE:${SOURCE_DIR}>)
   target_compile_features(h5xx INTERFACE cxx_std_11)
   target_compile_definitions(h5xx INTERFACE H5XX_USE_MPI)
   add_library(espresso_h5xx_cpp_flags INTERFACE)
@@ -670,6 +666,11 @@ endif()
 # Boost
 #
 
+if(POLICY CMP0167)
+  # use BoostConfig.cmake shipped with Boost 1.70+ instead of the one in CMake
+  cmake_policy(SET CMP0167 NEW)
+endif()
+
 list(APPEND BOOST_COMPONENTS mpi serialization filesystem system)
 
 if(ESPRESSO_BUILD_TESTS)
diff --git a/cmake/FindCUDACompilerNVCC.cmake b/cmake/FindCUDACompilerNVCC.cmake
index d9600ecf6d7..40213d2ad32 100644
--- a/cmake/FindCUDACompilerNVCC.cmake
+++ b/cmake/FindCUDACompilerNVCC.cmake
@@ -19,22 +19,9 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #
 
-# Verify the NVCC compiler matches the NVIDIA toolkit,
 # include the toolkit libraries and declare a custom
 # `add_library()` wrapper function named `espresso_add_gpu_library()`.
 
-file(REAL_PATH "${CUDAToolkit_ROOT}/bin/nvcc" ESPRESO_CUDAToolkit_ROOT_RESOLVED)
-file(REAL_PATH "${CMAKE_CUDA_COMPILER}" ESPRESO_CMAKE_CUDA_COMPILER_RESOLVED)
-if(NOT "${ESPRESO_CUDAToolkit_ROOT_RESOLVED}" STREQUAL "${ESPRESO_CMAKE_CUDA_COMPILER_RESOLVED}"
-   AND NOT ESPRESSO_INSIDE_DOCKER)
-  cmake_path(GET CMAKE_CUDA_COMPILER PARENT_PATH ESPRESSO_NVCC_EXECUTABLE_DIRNAME)
-  cmake_path(GET ESPRESSO_NVCC_EXECUTABLE_DIRNAME PARENT_PATH ESPRESSO_NVCC_EXECUTABLE_DIRNAME)
-  message(
-    WARNING
-      "Your nvcc compiler (${CMAKE_CUDA_COMPILER}) does not appear to match your CUDA toolkit installation (${CUDAToolkit_ROOT}). While ESPResSo will still compile, you might get unexpected crashes. Try hinting it with '-D CUDAToolkit_ROOT=\"${ESPRESSO_NVCC_EXECUTABLE_DIRNAME}\"'."
-  )
-endif()
-
 set(CUDA_LINK_LIBRARIES_KEYWORD PUBLIC)
 set(CUDA_PROPAGATE_HOST_FLAGS OFF)
 
diff --git a/cmake/walberla.patch b/cmake/walberla.patch
index d2c8d8e24fb..46b4ab08d17 100644
--- a/cmake/walberla.patch
+++ b/cmake/walberla.patch
@@ -9,3 +9,9 @@ https://i10git.cs.fau.de/walberla/walberla/-/merge_requests/709
 @@ -700 +700 @@
 -   begin_ = new T[0];
 +   begin_ = nullptr;
+support for CMake 4.0
+--- cmake/FindOpenMesh.cmake
++++ cmake/FindOpenMesh.cmake
+@@ -56 +56 @@
+-cmake_minimum_required(VERSION 3.5.0)
++cmake_minimum_required(VERSION 3.10.0)