From 93ed09f48d729924dab832034312e9c83a53d26d Mon Sep 17 00:00:00 2001
From: Jan Kotanski <jankotan@gmail.com>
Date: Wed, 25 Mar 2026 07:55:21 +0100
Subject: [PATCH] add H5CPP_OLD_CMAKE switch

---
 .github/workflows/cmake-build.yml |  2 +-
 CMakeLists.txt                    | 16 ++++++++++++----
 cmake/{ => old}/FindHDF5.cmake    |  0
 3 files changed, 13 insertions(+), 5 deletions(-)
 rename cmake/{ => old}/FindHDF5.cmake (100%)

diff --git a/.github/workflows/cmake-build.yml b/.github/workflows/cmake-build.yml
index 7535e11c12..cda19e1003 100644
--- a/.github/workflows/cmake-build.yml
+++ b/.github/workflows/cmake-build.yml
@@ -295,7 +295,7 @@ jobs:
         run: |
           docker  exec  --user root build  /bin/bash -c "chown -R p00user /home/p00user/src"
           docker  exec build /bin/bash -c "HDF5_STATIC=ON; [ \"${H5CPP_SHARED}\" = \"True\" ] && HDF5_STATIC=OFF; git config --global --add safe.directory /home/p00user/src && mkdir ../build &&  cd ../build &&
-          cmake ../src -DCMAKE_BUILD_TYPE=Release -DH5CPP_CONAN=DISABLE -DH5CPP_CATCH2_V2=TRUE -DHDF5_USE_STATIC_LIBRARIES=${HDF5_STATIC} -DH5CPP_BUILD_SHARED=${H5CPP_SHARED}  -DH5CPP_WITH_BOOST=${H5CPP_WITH_BOOST} -DH5CPP_WITH_MPI=${H5CPP_WITH_MPI}"
+          cmake ../src -DCMAKE_BUILD_TYPE=Release -DH5CPP_CONAN=DISABLE -DH5CPP_OLD_CMAKE=ON -DH5CPP_CATCH2_V2=TRUE -DHDF5_USE_STATIC_LIBRARIES=${HDF5_STATIC} -DH5CPP_BUILD_SHARED=${H5CPP_SHARED}  -DH5CPP_WITH_BOOST=${H5CPP_WITH_BOOST} -DH5CPP_WITH_MPI=${H5CPP_WITH_MPI}"
       - name: Build all
         run: docker  exec build /bin/bash -c "cd ../build &&  cmake --build . -- -j 2"
       - name: Build html
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2a1eb40ee4..b41d1d63aa 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,6 +6,7 @@ project(h5cpp
       VERSION 0.7
     )
 
+option(H5CPP_OLD_CMAKE "enable support for old cmake versions" OFF)
 
 #=============================================================================
 # Augment CMake with our custom scripts
@@ -13,6 +14,11 @@ project(h5cpp
 set(EXTRA_MODULES_DIR ${CMAKE_CURRENT_SOURCE_DIR}/cmake)
 list(APPEND CMAKE_MODULE_PATH ${EXTRA_MODULES_DIR})
 
+if (H5CPP_OLD_CMAKE)
+  set(EXTRA_OLDMODULES_DIR ${CMAKE_CURRENT_SOURCE_DIR}/cmake/old)
+  list(APPEND CMAKE_MODULE_PATH ${EXTRA_OLDMODULES_DIR})
+endif()
+
 if (NOT DEFINED BUILD_SHARED_LIBS)
   set(BUILD_SHARED_LIBS ON)
 endif()
@@ -171,10 +177,12 @@ install(FILES
     DESTINATION ${CMAKE_INSTALL_PACKAGEDIR}
     COMPONENT development)
 
-install(FILES
-        cmake/FindHDF5.cmake
-        DESTINATION ${CMAKE_INSTALL_PACKAGEDIR}/hdf5
-        COMPONENT development)
+if (H5CPP_OLD_CMAKE)
+  install(FILES
+    cmake/old/FindHDF5.cmake
+    DESTINATION ${CMAKE_INSTALL_PACKAGEDIR}/hdf5
+    COMPONENT development)
+endif()
 
 #
 # uninstall target
diff --git a/cmake/FindHDF5.cmake b/cmake/old/FindHDF5.cmake
similarity index 100%
rename from cmake/FindHDF5.cmake
rename to cmake/old/FindHDF5.cmake