From 49ae2f225a4bfbcf3ed724f16d09e30e06c8d636 Mon Sep 17 00:00:00 2001
From: Scot Breitenfeld <brtnfld@hdfgroup.org>
Date: Thu, 12 Feb 2026 14:10:39 -0600
Subject: [PATCH] Updates to #6205 (#6208)

* Fix MPI Fortran configuration for HDF5Examples (#6205)

When building Fortran parallel examples standalone without MPI
wrappers, the compiler cannot find mpi.mod because
MPI_Fortran_INCLUDE_DIRS is not populated.

* Use MPI::MPI_Fortran imported target instead of raw MPI variables

Replace manual MPI_Fortran_LIBRARIES, MPI_Fortran_LINK_FLAGS, and
MPI_Fortran_INCLUDE_DIRS usage with the MPI::MPI_Fortran imported
target, which transitively carries all include dirs, compile flags,
and link flags. This eliminates the CMAKE_Fortran_EXE_LINKER_FLAGS
hack and the manual target_include_directories in H5PAR.
---
 HDF5Examples/CMakeLists.txt               | 11 +----------
 HDF5Examples/FORTRAN/CMakeLists.txt       |  7 +++++++
 HDF5Examples/FORTRAN/H5PAR/CMakeLists.txt |  1 -
 3 files changed, 8 insertions(+), 11 deletions(-)

diff --git a/HDF5Examples/CMakeLists.txt b/HDF5Examples/CMakeLists.txt
index 23ca29e3ea1..cb5086c5ab8 100644
--- a/HDF5Examples/CMakeLists.txt
+++ b/HDF5Examples/CMakeLists.txt
@@ -143,18 +143,8 @@ if (${H5_LIBVER_DIR} GREATER 16)
   if (EXISTS "${H5EXAMPLES_SOURCE_DIR}/FORTRAN" AND IS_DIRECTORY "${H5EXAMPLES_SOURCE_DIR}/FORTRAN")
     option (H5EXAMPLE_BUILD_FORTRAN "Build examples FORTRAN support" OFF)
     if (H5EXAMPLE_BUILD_FORTRAN AND HDF5_PROVIDES_FORTRAN)
-      enable_language(Fortran)
       set (H5EXAMPLE_LINK_Fortran_LIBS ${H5EXAMPLE_HDF5_LINK_LIBS})
 
-      # Parallel IO usage requires MPI to be Linked and Included
-      if (H5_HAVE_PARALLEL)
-        find_package(MPI REQUIRED COMPONENTS Fortran)
-        set (H5EXAMPLE_LINK_Fortran_LIBS ${H5EXAMPLE_LINK_Fortran_LIBS} ${MPI_Fortran_LIBRARIES})
-        if (MPI_Fortran_LINK_FLAGS)
-          set (CMAKE_Fortran_EXE_LINKER_FLAGS "${MPI_Fortran_LINK_FLAGS} ${CMAKE_EXE_LINKER_FLAGS}")
-        endif ()
-      endif ()
-
       configure_file (${H5EXAMPLE_F90_SRC_DIR}/H5D/h5_version.h.in ${PROJECT_BINARY_DIR}/FORTRAN/H5D/h5_version.h @ONLY)
       configure_file (${H5EXAMPLE_F90_SRC_DIR}/H5D/h5_version.h.in ${PROJECT_BINARY_DIR}/FORTRAN/H5G/h5_version.h @ONLY)
     else ()
@@ -225,6 +215,7 @@ endif ()
 # Build examples
 #-----------------------------------------------------------------------------
 add_subdirectory (C)
+# Fortran MPI setup (find_package, link flags) is handled in FORTRAN/CMakeLists.txt
 if (H5EXAMPLE_BUILD_FORTRAN AND HDF5_PROVIDES_FORTRAN)
   add_subdirectory (FORTRAN)
 endif ()
diff --git a/HDF5Examples/FORTRAN/CMakeLists.txt b/HDF5Examples/FORTRAN/CMakeLists.txt
index bd4e24fbc7a..6ca9afb4ed2 100644
--- a/HDF5Examples/FORTRAN/CMakeLists.txt
+++ b/HDF5Examples/FORTRAN/CMakeLists.txt
@@ -1,6 +1,13 @@
 cmake_minimum_required (VERSION 3.26)
 PROJECT (HDF5Examples_F90 Fortran)
 
+# Parallel IO usage requires MPI to be linked and included
+if (H5_HAVE_PARALLEL)
+  find_package(MPI REQUIRED COMPONENTS Fortran)
+  # Use imported target — carries include dirs, compile flags, and link flags transitively
+  list(APPEND H5EXAMPLE_LINK_Fortran_LIBS MPI::MPI_Fortran)
+endif ()
+
 #-----------------------------------------------------------------------------
 # Build the Fortran Examples
 #-----------------------------------------------------------------------------
diff --git a/HDF5Examples/FORTRAN/H5PAR/CMakeLists.txt b/HDF5Examples/FORTRAN/H5PAR/CMakeLists.txt
index fc818f84b35..f50712b8d82 100644
--- a/HDF5Examples/FORTRAN/H5PAR/CMakeLists.txt
+++ b/HDF5Examples/FORTRAN/H5PAR/CMakeLists.txt
@@ -30,7 +30,6 @@ foreach (example_name ${examples})
           "$<$<BOOL:${${EXAMPLE_VARNAME}_USE_114_API}>:-DH5_USE_114_API>"
           "$<$<BOOL:${${EXAMPLE_VARNAME}_USE_200_API}>:-DH5_USE_200_API>"
   )
-  target_include_directories (${EXAMPLE_VARNAME}_f90_${example_name} PUBLIC ${MPI_Fortran_INCLUDE_DIRS})
   target_link_libraries (${EXAMPLE_VARNAME}_f90_${example_name} ${H5EXAMPLE_LINK_Fortran_LIBS})
   set_target_properties (${EXAMPLE_VARNAME}_f90_${example_name} PROPERTIES LINKER_LANGUAGE Fortran)
 endforeach ()