Fixing issues related to linking parallel hdf5 on cmake

CMakeLists.txt

@@ -42,6 +42,7 @@ include(ReplaceIdefixSource)
 include(AddIdefixSource)
 include(SetIdefixProperty)
 include(SetRequiredBuildSettingsForGCC8)
+include(CheckHdf5ParallelSupport)
 
 #Idefix requires Cuda Lambdas (experimental)
 if(Kokkos_ENABLE_CUDA)
@@ -113,12 +114,25 @@ if(Idefix_HDF5)
     PUBLIC src/output/xdmf.cpp
     PUBLIC src/output/xdmf.hpp
   )
-  find_package(HDF5 REQUIRED)
-  target_link_libraries(idefix "${HDF5_LIBRARIES}")
+  # Prefer imported targets (matches older working behavior), then fall back.
+  find_package(HDF5 QUIET COMPONENTS C)
+  if(NOT HDF5_FOUND)
+    find_package(HDF5 REQUIRED MODULE COMPONENTS C)
+  endif()
+
+  set(_idefix_hdf5_link_items "${HDF5_LIBRARIES}")
+  if(TARGET hdf5::hdf5)
+    set(_idefix_hdf5_link_items hdf5::hdf5)
+  elseif(TARGET HDF5::HDF5)
+    set(_idefix_hdf5_link_items HDF5::HDF5)
+  endif()
+
+  target_link_libraries(idefix ${_idefix_hdf5_link_items})
   message(STATUS "Found HDF5 include directories: ${HDF5_INCLUDE_DIRS}")
   target_include_directories(idefix PUBLIC "${HDF5_INCLUDE_DIRS}")
   if(Idefix_MPI)
-    if(NOT HDF5_IS_PARALLEL)
+    CheckHdf5ParallelSupport("${_idefix_hdf5_link_items}")
+    if(NOT IDEFIX_HDF5_IS_PARALLEL)
       message(FATAL_ERROR "Parallel HDF5 required for Idefix_MPI but the found HDF5 library does not support it")
     endif()
   endif()

cmake/CheckHdf5ParallelSupport.cmake

@@ -0,0 +1,50 @@
+include(CheckCSourceCompiles)
+
+# Check whether the HDF5 library found by find_package(HDF5) supports parallel
+# (MPI-IO) access, and store the result in IDEFIX_HDF5_IS_PARALLEL in the
+# caller's scope.
+#
+# Usage: CheckHdf5ParallelSupport(<hdf5_link_items>)
+# where <hdf5_link_items> is the list of HDF5 targets/libraries to link against.
+#
+# Some CMake/HDF5 combinations do not reliably set HDF5_IS_PARALLEL (e.g. when
+# HDF5 is found via its CMake config package rather than the FindHDF5 module).
+# Combine metadata checks with a compile+link probe for the MPI-IO symbols to
+# reliably detect parallel HDF5.
+function(CheckHdf5ParallelSupport hdf5_link_items)
+  set(_idefix_hdf5_is_parallel FALSE)
+  if(HDF5_IS_PARALLEL OR HDF5_C_IS_PARALLEL)
+    set(_idefix_hdf5_is_parallel TRUE)
+  endif()
+
+  if(NOT _idefix_hdf5_is_parallel AND DEFINED HDF5_C_COMPILER_EXECUTABLE)
+    execute_process(
+      COMMAND "${HDF5_C_COMPILER_EXECUTABLE}" -showconfig
+      OUTPUT_VARIABLE _idefix_hdf5_showconfig
+      ERROR_QUIET
+    )
+    if(_idefix_hdf5_showconfig MATCHES "Parallel HDF5:[ \t]*yes")
+      set(_idefix_hdf5_is_parallel TRUE)
+    endif()
+  endif()
+
+  set(CMAKE_REQUIRED_INCLUDES ${HDF5_INCLUDE_DIRS} ${MPI_C_INCLUDE_DIRS})
+  set(CMAKE_REQUIRED_LIBRARIES ${hdf5_link_items} MPI::MPI_C)
+  check_c_source_compiles(
+    "#include <mpi.h>
+     #include <hdf5.h>
+     int main(void) {
+       hid_t plist = H5Pcreate(H5P_FILE_ACCESS);
+       H5Pset_fapl_mpio(plist, MPI_COMM_WORLD, MPI_INFO_NULL);
+       H5Pclose(plist);
+       return 0;
+     }"
+    IDEFIX_HDF5_HAS_MPI_IO
+  )
+
+  if(IDEFIX_HDF5_HAS_MPI_IO)
+    set(_idefix_hdf5_is_parallel TRUE)
+  endif()
+
+  set(IDEFIX_HDF5_IS_PARALLEL ${_idefix_hdf5_is_parallel} PARENT_SCOPE)
+endfunction()

src/fluid/showConfig.hpp

@@ -60,7 +60,7 @@ void Fluid<Phys>::ShowConfig() {
                  << ": Ohmic resistivity ENABLED with user-defined resistivity function."
                  << std::endl;
       if(!ohmicDiffusivityFunc) {
-        IDEFIX_ERROR("No user-defined Ihmic resistivity function has been enrolled.");
+        IDEFIX_ERROR("No user-defined Ohmic resistivity function has been enrolled.");
       }
     } else {
       IDEFIX_ERROR("Unknown Ohmic resistivity mode");

src/output/xdmf.cpp

@@ -295,7 +295,7 @@ int Xdmf::Write() {
   #if DIMENSIONS == 1
   [[maybe_unused]] int tot_dim = 1;
   #elif DIMENSIONS == 2
-  int tot_dim = 2;
+  [[maybe_unused]] int tot_dim = 2;
   #elif DIMENSIONS == 3
   [[maybe_unused]] int tot_dim = 3;
   #endif