From 71f4d53b7398f11cb98eb4fe20e484003aa058b8 Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Thu, 16 Jan 2025 14:36:53 +1100
Subject: [PATCH 1/9] Update LoadMDTest and LoadNexusProcessedTest

---
 .../test/LoadNexusProcessedTest.h             | 23 ++++++++-----------
 Framework/MDAlgorithms/test/LoadMDTest.h      | 23 ++++++-------------
 2 files changed, 16 insertions(+), 30 deletions(-)

diff --git a/Framework/DataHandling/test/LoadNexusProcessedTest.h b/Framework/DataHandling/test/LoadNexusProcessedTest.h
index bf192583b898..a6cb5421bcf4 100644
--- a/Framework/DataHandling/test/LoadNexusProcessedTest.h
+++ b/Framework/DataHandling/test/LoadNexusProcessedTest.h
@@ -27,13 +27,14 @@
 #include "MantidGeometry/Instrument.h"
 #include "MantidGeometry/Instrument/InstrumentDefinitionParser.h"
 #include "MantidHistogramData/Histogram.h"
+#include "MantidNexus/H5Util.h"
+
+#include <H5Cpp.h>
 
 #include "SaveNexusProcessedTest.h"
 
 #include <cxxtest/TestSuite.h>
 
-#include <hdf5.h>
-
 #include <Poco/File.h>
 
 #include <string>
@@ -45,8 +46,11 @@ using namespace Mantid::Kernel;
 using namespace Mantid::DataObjects;
 using namespace Mantid::API;
 using namespace Mantid::HistogramData;
+using namespace Mantid::NeXus;
 using Mantid::detid_t;
 
+using namespace H5;
+
 // Note that this suite tests an old version of Nexus processed files that we
 // continue to support.
 // LoadRawSaveNxsLoadNxs tests the current version of Nexus processed by loading
@@ -797,18 +801,9 @@ class LoadNexusProcessedTest : public CxxTest::TestSuite {
 
     // Remove the coordinate_system entry so it falls back on the log. NeXus
     // can't do this so use the HDF5 API directly
-    auto fid = H5Fopen(filePath.c_str(), H5F_ACC_RDWR, H5P_DEFAULT);
-    auto mantid_id = H5Gopen(fid, "mantid_workspace_1", H5P_DEFAULT);
-    auto peaks_id = H5Gopen(mantid_id, "peaks_workspace", H5P_DEFAULT);
-    if (peaks_id > 0) {
-      H5Ldelete(peaks_id, "coordinate_system", H5P_DEFAULT);
-      H5Gclose(peaks_id);
-      H5Gclose(mantid_id);
-    } else {
-      TS_FAIL("Cannot unlink coordinate_system group. Test file has unexpected "
-              "structure.");
-    }
-    H5Fclose(fid);
+    H5File h5file(filePath.c_str(), H5F_ACC_RDWR);
+    H5Util::deleteObjectLink(h5file, "/mantid_workspace_1/peaks_workspace/coordinate_system");
+    h5file.close();
 
     LoadNexusProcessed loadAlg;
     loadAlg.setChild(true);
diff --git a/Framework/MDAlgorithms/test/LoadMDTest.h b/Framework/MDAlgorithms/test/LoadMDTest.h
index 378238cc32f3..e65f6f2c48eb 100644
--- a/Framework/MDAlgorithms/test/LoadMDTest.h
+++ b/Framework/MDAlgorithms/test/LoadMDTest.h
@@ -23,16 +23,18 @@
 #include "MantidGeometry/MDGeometry/QSample.h"
 #include "MantidKernel/Strings.h"
 #include "MantidMDAlgorithms/LoadMD.h"
+#include "MantidNexus/H5Util.h"
+#include <H5Cpp.h>
 
 #include <cxxtest/TestSuite.h>
 
-#include <hdf5.h>
-
 using namespace Mantid;
 using namespace Mantid::DataObjects;
 using namespace Mantid::MDAlgorithms;
 using namespace Mantid::API;
 using namespace Mantid::Kernel;
+using namespace Mantid::NeXus;
+using namespace H5;
 
 class LoadMDTest : public CxxTest::TestSuite {
 public:
@@ -618,7 +620,7 @@ class LoadMDTest : public CxxTest::TestSuite {
   }
 
   Mantid::API::IMDWorkspace_sptr testSaveAndLoadWorkspace(const Mantid::API::IMDWorkspace_sptr &inputWS,
-                                                          const char *rootGroup, const bool rmCoordField = false) {
+                                                          std::string rootGroup, const bool rmCoordField = false) {
     const std::string fileName = "SaveMDSpecialCoordinatesTest.nxs";
     SaveMD2 saveAlg;
     saveAlg.setChild(true);
@@ -630,19 +632,8 @@ class LoadMDTest : public CxxTest::TestSuite {
     std::string this_fileName = saveAlg.getProperty("Filename");
 
     if (rmCoordField) {
-      // Remove the coordinate_system entry so it falls back on the log. NeXus
-      // can't do this
-      // so use the HDF5 API directly
-      auto fid = H5Fopen(this_fileName.c_str(), H5F_ACC_RDWR, H5P_DEFAULT);
-      auto gid = H5Gopen(fid, rootGroup, H5P_DEFAULT);
-      if (gid > 0) {
-        H5Ldelete(gid, "coordinate_system", H5P_DEFAULT);
-        H5Gclose(gid);
-      } else {
-        TS_FAIL("Cannot open MDEventWorkspace group. Test file has unexpected "
-                "structure.");
-      }
-      H5Fclose(fid);
+      H5File h5file(this_fileName.c_str(), H5F_ACC_RDWR);
+      H5Util::deleteObjectLink(h5file, rootGroup + "/coordinate_system");
     }
 
     LoadMD loadAlg;

From 28c5ef615c67ce8adbfe166c8addacf75b5602a0 Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Fri, 17 Jan 2025 12:36:42 +1100
Subject: [PATCH 2/9] Update LoadSassena

---
 .../inc/MantidDataHandling/LoadSassena.h      | 12 ++--
 Framework/DataHandling/src/LoadSassena.cpp    | 72 ++++++++-----------
 2 files changed, 37 insertions(+), 47 deletions(-)

diff --git a/Framework/DataHandling/inc/MantidDataHandling/LoadSassena.h b/Framework/DataHandling/inc/MantidDataHandling/LoadSassena.h
index 1ddb6e162ef8..9e4015e8f99b 100644
--- a/Framework/DataHandling/inc/MantidDataHandling/LoadSassena.h
+++ b/Framework/DataHandling/inc/MantidDataHandling/LoadSassena.h
@@ -15,7 +15,7 @@
 #include "MantidDataObjects/Workspace2D.h"
 #include "MantidKernel/NexusDescriptor.h"
 
-#include <hdf5.h>
+#include <H5Cpp.h>
 
 namespace Mantid {
 
@@ -62,17 +62,17 @@ class MANTID_DATAHANDLING_DLL LoadSassena : public API::IFileLoader<Kernel::Nexu
   void registerWorkspace(const API::WorkspaceGroup_sptr &gws, const std::string &wsName,
                          const DataObjects::Workspace2D_sptr &ws, const std::string &description);
   /// Read info about one HDF5 dataset, log if error
-  herr_t dataSetInfo(const hid_t &h5file, const std::string &setName, hsize_t *dims) const;
+  void dataSetInfo(const H5::H5File &h5file, const std::string &setName, hsize_t *dims) const;
   /// Read dataset data to a buffer ot type double
-  herr_t dataSetDouble(const hid_t &h5file, const std::string &setName, std::vector<double> &buf);
+  void dataSetDouble(const H5::H5File &h5file, const std::string &setName, std::vector<double> &buf);
   /// Load qvectors dataset, calculate modulus of vectors
-  HistogramData::Points loadQvectors(const hid_t &h5file, const API::WorkspaceGroup_sptr &gws,
+  HistogramData::Points loadQvectors(const H5::H5File &h5file, const API::WorkspaceGroup_sptr &gws,
                                      std::vector<int> &sorting_indexes);
   /// Load structure factor asa function of q-vector modulus
-  void loadFQ(const hid_t &h5file, const API::WorkspaceGroup_sptr &gws, const std::string &setName,
+  void loadFQ(const H5::H5File &h5file, const API::WorkspaceGroup_sptr &gws, const std::string &setName,
               const HistogramData::Points &qvmod, const std::vector<int> &sorting_indexes);
   /// Load time-dependent structure factor
-  void loadFQT(const hid_t &h5file, const API::WorkspaceGroup_sptr &gws, const std::string &setName,
+  void loadFQT(const H5::H5File &h5file, const API::WorkspaceGroup_sptr &gws, const std::string &setName,
                const HistogramData::Points &qvmod, const std::vector<int> &sorting_indexes);
 
 private:
diff --git a/Framework/DataHandling/src/LoadSassena.cpp b/Framework/DataHandling/src/LoadSassena.cpp
index 1616e5a976e7..23eb94d0705d 100644
--- a/Framework/DataHandling/src/LoadSassena.cpp
+++ b/Framework/DataHandling/src/LoadSassena.cpp
@@ -17,8 +17,7 @@
 #include "MantidKernel/Exception.h"
 #include "MantidKernel/Unit.h"
 #include "MantidKernel/UnitFactory.h"
-
-#include <hdf5_hl.h>
+#include "MantidNexus/H5Util.h"
 
 #include <utility>
 
@@ -61,14 +60,8 @@ void LoadSassena::registerWorkspace(const API::WorkspaceGroup_sptr &gws, const s
  * @param dims storing dimensionality
  */
 
-herr_t LoadSassena::dataSetInfo(const hid_t &h5file, const std::string &setName, hsize_t *dims) const {
-  H5T_class_t class_id;
-  size_t type_size;
-  herr_t errorcode = H5LTget_dataset_info(h5file, setName.c_str(), dims, &class_id, &type_size);
-  if (errorcode < 0) {
-    g_log.error("Unable to read " + setName + " dataset info");
-  }
-  return errorcode;
+void LoadSassena::dataSetInfo(const H5::H5File &h5file, const std::string &setName, hsize_t *dims) const {
+  h5file.openDataSet(setName).getSpace().getSimpleExtentDims(dims);
 }
 
 /**
@@ -77,12 +70,8 @@ herr_t LoadSassena::dataSetInfo(const hid_t &h5file, const std::string &setName,
  * @param setName string name of dataset
  * @param buf storing dataset
  */
-herr_t LoadSassena::dataSetDouble(const hid_t &h5file, const std::string &setName, std::vector<double> &buf) {
-  herr_t errorcode = H5LTread_dataset_double(h5file, setName.c_str(), buf.data());
-  if (errorcode < 0) {
-    this->g_log.error("Cannot read " + setName + " dataset");
-  }
-  return errorcode;
+void LoadSassena::dataSetDouble(const H5::H5File &h5file, const std::string &setName, std::vector<double> &buf) {
+  Mantid::NeXus::H5Util::readArray1DCoerce(h5file.openDataSet(setName), buf);
 }
 
 /* Helper object and function to sort modulus of Q-vectors
@@ -100,7 +89,7 @@ bool compare(const mypair &left, const mypair &right) { return left.first < righ
  * @param sorting_indexes permutation of qvmod indexes to render it in
  * increasing order of momemtum transfer
  */
-HistogramData::Points LoadSassena::loadQvectors(const hid_t &h5file, const API::WorkspaceGroup_sptr &gws,
+HistogramData::Points LoadSassena::loadQvectors(const H5::H5File &h5file, const API::WorkspaceGroup_sptr &gws,
                                                 std::vector<int> &sorting_indexes) {
 
   // store the modulus of the vector
@@ -110,14 +99,18 @@ HistogramData::Points LoadSassena::loadQvectors(const hid_t &h5file, const API::
   const std::string setName("qvectors");
 
   hsize_t dims[3];
-  if (dataSetInfo(h5file, setName, dims) < 0) {
+  try {
+    dataSetInfo(h5file, setName, dims);
+  } catch (H5::Exception &e) {
     throw Kernel::Exception::FileError("Unable to read " + setName + " dataset info:", m_filename);
   }
+
   auto nq = static_cast<int>(dims[0]); // number of q-vectors
   std::vector<double> buf(nq * 3);
 
-  herr_t errorcode = this->dataSetDouble(h5file, "qvectors", buf);
-  if (errorcode < 0) {
+  try {
+    this->dataSetDouble(h5file, "qvectors", buf);
+  } catch (H5::Exception &e) {
     this->g_log.error("LoadSassena::loadQvectors cannot proceed");
     qvmod.resize(0);
     return HistogramData::Points(std::move(qvmod));
@@ -169,13 +162,14 @@ HistogramData::Points LoadSassena::loadQvectors(const hid_t &h5file, const API::
  * @param sorting_indexes permutation of qvmod indexes to render it in
  * increasing order of momemtum transfer
  */
-void LoadSassena::loadFQ(const hid_t &h5file, const API::WorkspaceGroup_sptr &gws, const std::string &setName,
+void LoadSassena::loadFQ(const H5::H5File &h5file, const API::WorkspaceGroup_sptr &gws, const std::string &setName,
                          const HistogramData::Points &qvmod, const std::vector<int> &sorting_indexes) {
 
   auto nq = static_cast<int>(qvmod.size()); // number of q-vectors
   std::vector<double> buf(nq * 2);
-  herr_t errorcode = this->dataSetDouble(h5file, setName, buf);
-  if (errorcode < 0) {
+  try {
+    this->dataSetDouble(h5file, setName, buf);
+  } catch (H5::Exception &e) {
     this->g_log.error("LoadSassena::loadFQ cannot proceed");
     return;
   }
@@ -217,11 +211,13 @@ void LoadSassena::loadFQ(const hid_t &h5file, const API::WorkspaceGroup_sptr &gw
  * @param sorting_indexes permutation of qvmod indexes to render it in
  * increasing order of momemtum transfer
  */
-void LoadSassena::loadFQT(const hid_t &h5file, const API::WorkspaceGroup_sptr &gws, const std::string &setName,
+void LoadSassena::loadFQT(const H5::H5File &h5file, const API::WorkspaceGroup_sptr &gws, const std::string &setName,
                           const HistogramData::Points &qvmod, const std::vector<int> &sorting_indexes) {
 
   hsize_t dims[3];
-  if (dataSetInfo(h5file, setName, dims) < 0) {
+  try {
+    dataSetInfo(h5file, setName, dims);
+  } catch (H5::Exception &) {
     this->g_log.error("Unable to read " + setName + " dataset info");
     this->g_log.error("LoadSassena::loadFQT cannot proceed");
     return;
@@ -231,8 +227,9 @@ void LoadSassena::loadFQT(const hid_t &h5file, const API::WorkspaceGroup_sptr &g
 
   auto nq = static_cast<int>(qvmod.size()); // number of q-vectors
   std::vector<double> buf(nq * nnt * 2);
-  herr_t errorcode = this->dataSetDouble(h5file, setName, buf);
-  if (errorcode < 0) {
+  try {
+    this->dataSetDouble(h5file, setName, buf);
+  } catch (H5::Exception &e) {
     this->g_log.error("LoadSassena::loadFQT cannot proceed");
     return;
   }
@@ -356,34 +353,27 @@ void LoadSassena::exec() {
 
   // open the HDF5 file for reading
   m_filename = this->getPropertyValue("Filename");
-  hid_t h5file = H5Fopen(m_filename.c_str(), H5F_ACC_RDONLY, H5P_DEFAULT);
-  if (h5file < 0) {
+  H5::H5File h5file;
+  try {
+    h5file = H5::H5File(m_filename.c_str(), H5F_ACC_RDONLY);
+  } catch (H5::FileIException &e) {
     this->g_log.error("Cannot open " + m_filename);
     throw Kernel::Exception::FileError("Unable to open:", m_filename);
   }
 
-  // find out the sassena version used
-  char cversion[16];
-  if (H5LTget_attribute_string(h5file, "/", "sassena_version", cversion) < 0) {
-    this->g_log.error("Unable to read Sassena version");
-  }
-  // const std::string version(cversion);
-  // determine which loader protocol to use based on the version
-  // to be done at a later time, maybe implement a Version class
-
   // Block to read the Q-vectors
   std::vector<int> sorting_indexes;
   const auto qvmod = this->loadQvectors(h5file, gws, sorting_indexes);
   if (qvmod.empty()) {
     this->g_log.error("No Q-vectors read. Unable to proceed");
-    H5Fclose(h5file);
+    h5file.close();
     return;
   }
 
   // iterate over the valid sets
   for (std::vector<std::string>::const_iterator it = this->m_validSets.begin(); it != this->m_validSets.end(); ++it) {
     std::string setName = *it;
-    if (H5Lexists(h5file, setName.c_str(), H5P_DEFAULT)) {
+    if (h5file.nameExists(setName)) {
       if (setName == "fq" || setName == "fq0" || setName == "fq2")
         this->loadFQ(h5file, gws, setName, qvmod, sorting_indexes);
       else if (setName == "fqt")
@@ -392,7 +382,7 @@ void LoadSassena::exec() {
       this->g_log.information("Dataset " + setName + " not present in file");
   } // end of iterate over the valid sets
 
-  H5Fclose(h5file);
+  h5file.close();
 } // end of LoadSassena::exec()
 
 } // namespace Mantid::DataHandling

From 6b978985bae065857be8069a818ff97b5d889f7e Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Fri, 17 Jan 2025 13:30:26 +1100
Subject: [PATCH 3/9] Update SaveNXSPETest

---
 Framework/DataHandling/src/LoadNXcanSAS.cpp   |  8 ----
 Framework/DataHandling/test/SaveNXSPETest.h   | 44 ++++++++-----------
 Framework/Kernel/CMakeLists.txt               |  1 -
 Framework/NexusCpp/CMakeLists.txt             |  2 +-
 buildconfig/CMake/CommonSetup.cmake           |  3 +-
 .../CMake/MantidFrameworkConfig.cmake.in      |  2 +-
 6 files changed, 22 insertions(+), 38 deletions(-)

diff --git a/Framework/DataHandling/src/LoadNXcanSAS.cpp b/Framework/DataHandling/src/LoadNXcanSAS.cpp
index f21e21a347d8..8ec00e4e40d1 100644
--- a/Framework/DataHandling/src/LoadNXcanSAS.cpp
+++ b/Framework/DataHandling/src/LoadNXcanSAS.cpp
@@ -483,15 +483,7 @@ void loadTransmissionData(H5::Group &transmission, const Mantid::API::MatrixWork
   else if (lambda.size() == workspace->blocksize() + 1)
     workspace->setBinEdges(0, std::move(lambda));
   else {
-#if defined(H5_USE_18_API)
     const std::string objectName{transmission.getObjName()};
-#else
-    const size_t nchars = H5Iget_name(transmission.getId(), nullptr, 0);
-    std::string objectName;
-    objectName.resize(nchars);
-    H5Iget_name(transmission.getId(), objectName.data(),
-                nchars + 1); // +1 for null terminator
-#endif
     throw std::runtime_error("Unexpected array size for lambda in transmission group '" + objectName +
                              "'. Expected length=" + std::to_string(workspace->blocksize()) +
                              ", found length=" + std::to_string(lambda.size()));
diff --git a/Framework/DataHandling/test/SaveNXSPETest.h b/Framework/DataHandling/test/SaveNXSPETest.h
index 86d2ae55b09f..556f3c19481a 100644
--- a/Framework/DataHandling/test/SaveNXSPETest.h
+++ b/Framework/DataHandling/test/SaveNXSPETest.h
@@ -23,8 +23,8 @@
 #include "boost/tuple/tuple.hpp"
 #include <memory>
 
-#include <hdf5.h>
-#include <hdf5_hl.h>
+#include "MantidNexus/H5Util.h"
+#include <H5Cpp.h>
 
 #include <Poco/File.h>
 
@@ -261,53 +261,47 @@ class SaveNXSPETest : public CxxTest::TestSuite {
                                std::vector<double>());
     }
 
-    auto h5file = H5Fopen(outputFile.c_str(), H5F_ACC_RDWR, H5P_DEFAULT);
+    H5::H5File h5file(outputFile, H5F_ACC_RDONLY);
     const char *dset = "/mantid_workspace/data/data";
     int rank(0);
-    herr_t status = H5LTget_dataset_ndims(h5file, dset, &rank);
-    TS_ASSERT_EQUALS(0, status);
+    H5::DataSet dataset = h5file.openDataSet(dset);
+    rank = dataset.getSpace().getSimpleExtentNdims();
     TS_ASSERT_EQUALS(2, rank);
 
     std::vector<hsize_t> dims(rank);
-    H5T_class_t classId(H5T_NO_CLASS);
-    size_t typeSize(0);
-    status = H5LTget_dataset_info(h5file, dset, dims.data(), &classId, &typeSize);
-    TS_ASSERT_EQUALS(0, status);
-    TS_ASSERT_EQUALS(H5T_FLOAT, classId);
-    TS_ASSERT_EQUALS(8, typeSize);
+    dataset.getSpace().getSimpleExtentDims(dims.data());
+    H5::DataType dataType = dataset.getDataType();
+    TS_ASSERT_EQUALS(H5T_FLOAT, dataType.getClass());
+    TS_ASSERT_EQUALS(8, dataType.getSize());
 
     size_t bufferSize(dims[0] * dims[1]);
     std::vector<double> signal(bufferSize), error(bufferSize);
-    status = H5LTread_dataset_double(h5file, dset, signal.data());
-    TS_ASSERT_EQUALS(0, status);
+    Mantid::NeXus::H5Util::readArray1DCoerce(dataset, signal);
 
     const char *dsetErr = "/mantid_workspace/data/error";
-    status = H5LTread_dataset_double(h5file, dsetErr, error.data());
-    TS_ASSERT_EQUALS(0, status);
+    Mantid::NeXus::H5Util::readArray1DCoerce(h5file.openDataSet(dsetErr), error);
     //---------------------------------------------------------------
     // check efixed
     const char *efixed_dset = "/mantid_workspace/NXSPE_info/fixed_energy";
-    status = H5LTget_dataset_ndims(h5file, efixed_dset, &rank);
-    TS_ASSERT_EQUALS(0, status);
+    H5::DataSet efixed_dataset = h5file.openDataSet(efixed_dset);
+    rank = efixed_dataset.getSpace().getSimpleExtentNdims();
     TS_ASSERT_EQUALS(1, rank);
 
     std::vector<hsize_t> efix_dims(rank);
-    status = H5LTget_dataset_info(h5file, efixed_dset, efix_dims.data(), &classId, &typeSize);
-    TS_ASSERT_EQUALS(0, status);
-    TS_ASSERT_EQUALS(H5T_FLOAT, classId);
-    TS_ASSERT_EQUALS(8, typeSize);
+    efixed_dataset.getSpace().getSimpleExtentDims(efix_dims.data());
+    H5::DataType efixed_dataType = efixed_dataset.getDataType();
+    TS_ASSERT_EQUALS(H5T_FLOAT, efixed_dataType.getClass());
+    TS_ASSERT_EQUALS(8, efixed_dataType.getSize());
 
     size_t EnBuffer(efix_dims[0]);
     std::vector<double> efixed(EnBuffer);
-    status = H5LTread_dataset_double(h5file, efixed_dset, efixed.data());
-    TS_ASSERT_EQUALS(0, status);
+    Mantid::NeXus::H5Util::readArray1DCoerce(efixed_dataset, efixed);
     if (set_efixed) {
       TS_ASSERT_EQUALS(EnBuffer, 1);
       TS_ASSERT_DELTA(efixed[0], efix_value, 1.e-8);
     }
 
-    H5Fclose(h5file);
-    // Poco::File(outputFile).remove();
+    h5file.close();
 
     return boost::make_tuple(dims, signal, error, efixed);
   }
diff --git a/Framework/Kernel/CMakeLists.txt b/Framework/Kernel/CMakeLists.txt
index 804185f6682e..322b0a364ccd 100644
--- a/Framework/Kernel/CMakeLists.txt
+++ b/Framework/Kernel/CMakeLists.txt
@@ -498,7 +498,6 @@ target_link_libraries(
          GSL::gsl
          OpenSSL::SSL
          ${HDF5_LIBRARIES}
-         ${HDF5_HL_LIBRARIES}
   PRIVATE ${NETWORK_LIBRARIES}
 )
 if(WIN32)
diff --git a/Framework/NexusCpp/CMakeLists.txt b/Framework/NexusCpp/CMakeLists.txt
index 482f352f7869..bbfab838b64e 100644
--- a/Framework/NexusCpp/CMakeLists.txt
+++ b/Framework/NexusCpp/CMakeLists.txt
@@ -39,7 +39,7 @@ set_target_properties(
 )
 # H5_BUILT_AS_DYNAMIC_LIB required https://github.com/conda-forge/hdf5-feedstock/issues/58
 target_compile_definitions(NexusCpp PUBLIC -DH5_BUILT_AS_DYNAMIC_LIB)
-target_link_libraries(NexusCpp PUBLIC ${HDF4_DF_LIBRARY} ${HDF4_MFHDF_LIBRARY} ${HDF5_LIBRARIES} ${HDF5_HL_LIBRARIES})
+target_link_libraries(NexusCpp PUBLIC ${HDF4_DF_LIBRARY} ${HDF4_MFHDF_LIBRARY} ${HDF5_LIBRARIES})
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "Darwin")
   set_target_properties(NexusCpp PROPERTIES INSTALL_RPATH "@loader_path/../MacOS;@loader_path/../Frameworks")
diff --git a/buildconfig/CMake/CommonSetup.cmake b/buildconfig/CMake/CommonSetup.cmake
index ab60b9217889..7da4bd194f81 100644
--- a/buildconfig/CMake/CommonSetup.cmake
+++ b/buildconfig/CMake/CommonSetup.cmake
@@ -102,11 +102,10 @@ if(BUILD_MANTIDFRAMEWORK)
 
   find_package(
     HDF5 MODULE
-    COMPONENTS C CXX HL
+    COMPONENTS C CXX
     REQUIRED
   )
   set(HDF5_LIBRARIES hdf5::hdf5_cpp hdf5::hdf5)
-  set(HDF5_HL_LIBRARIES hdf5::hdf5_hl)
 endif()
 
 if(ENABLE_WORKBENCH)
diff --git a/buildconfig/CMake/MantidFrameworkConfig.cmake.in b/buildconfig/CMake/MantidFrameworkConfig.cmake.in
index b7598476b063..7dd324604e8f 100644
--- a/buildconfig/CMake/MantidFrameworkConfig.cmake.in
+++ b/buildconfig/CMake/MantidFrameworkConfig.cmake.in
@@ -12,7 +12,7 @@ find_dependency(GSL)
 find_dependency(HDF5)
 find_dependency(OpenSSL)
 find_dependency(OpenMP COMPONENTS CXX)
-find_dependency(HDF5 COMPONENTS C CXX HL)
+find_dependency(HDF5 COMPONENTS C CXX)
 find_dependency(Eigen3)
 
 set(_mypackage_module_path_save "${CMAKE_MODULE_PATH}")

From c233036d19e8eb91520a642c773c49c1a3333331 Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Fri, 17 Jan 2025 14:37:16 +1100
Subject: [PATCH 4/9] Remove H5ForwardCompatibility

---
 Framework/NexusGeometry/CMakeLists.txt        |  2 -
 .../H5ForwardCompatibility.h                  | 31 ---------
 .../src/H5ForwardCompatibility.cpp            | 64 -------------------
 .../NexusGeometry/src/NexusGeometryParser.cpp | 24 ++++---
 .../NexusGeometry/src/NexusGeometrySave.cpp   | 35 +++++-----
 .../src/NexusGeometryUtilities.cpp            |  3 +-
 .../NexusFileReader.h                         |  1 -
 7 files changed, 29 insertions(+), 131 deletions(-)
 delete mode 100644 Framework/NexusGeometry/inc/MantidNexusGeometry/H5ForwardCompatibility.h
 delete mode 100644 Framework/NexusGeometry/src/H5ForwardCompatibility.cpp

diff --git a/Framework/NexusGeometry/CMakeLists.txt b/Framework/NexusGeometry/CMakeLists.txt
index fbae216c8e12..aad31f12cab5 100644
--- a/Framework/NexusGeometry/CMakeLists.txt
+++ b/Framework/NexusGeometry/CMakeLists.txt
@@ -1,5 +1,4 @@
 set(SRC_FILES
-    src/H5ForwardCompatibility.cpp
     src/Hdf5Version.cpp
     src/InstrumentBuilder.cpp
     src/JSONGeometryParser.cpp
@@ -14,7 +13,6 @@ set(SRC_FILES
 
 set(INC_FILES
     inc/MantidNexusGeometry/AbstractLogger.h
-    inc/MantidNexusGeometry/H5ForwardCompatibility.h
     inc/MantidNexusGeometry/Hdf5Version.h
     inc/MantidNexusGeometry/InstrumentBuilder.h
     inc/MantidNexusGeometry/JSONGeometryParser.h
diff --git a/Framework/NexusGeometry/inc/MantidNexusGeometry/H5ForwardCompatibility.h b/Framework/NexusGeometry/inc/MantidNexusGeometry/H5ForwardCompatibility.h
deleted file mode 100644
index a7e9602cc95e..000000000000
--- a/Framework/NexusGeometry/inc/MantidNexusGeometry/H5ForwardCompatibility.h
+++ /dev/null
@@ -1,31 +0,0 @@
-// Mantid Repository : https://github.com/mantidproject/mantid
-//
-// Copyright &copy; 2018 ISIS Rutherford Appleton Laboratory UKRI,
-//   NScD Oak Ridge National Laboratory, European Spallation Source,
-//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
-// SPDX - License - Identifier: GPL - 3.0 +
-#pragma once
-
-#include "MantidNexusGeometry/DllConfig.h"
-#include <H5Cpp.h>
-#include <string>
-
-// Use forward compatibility for lower than 1.8.13 versions of HDF5
-#if ((H5_VERS_MAJOR > 1) || (H5_VERS_MAJOR >= 1 && H5_VERS_MINOR > 8) ||                                               \
-     (H5_VERS_MAJOR >= 1 && H5_VERS_MINOR >= 8 && H5_VERS_RELEASE > 12))
-#define H5_OBJ_NAME(obj) obj.getObjName()
-#else
-#define H5_OBJ_NAME(obj) Mantid::NexusGeometry::H5ForwardCompatibility::getObjName(obj)
-#endif
-
-namespace Mantid {
-namespace NexusGeometry {
-namespace H5ForwardCompatibility {
-
-ssize_t getObjName(const H5::H5Object &obj, char *obj_name, size_t buf_size);
-std::string getObjName(const H5::H5Object &obj);
-std::string getObjName(const H5::H5File &obj);
-
-} // namespace H5ForwardCompatibility
-} // namespace NexusGeometry
-} // namespace Mantid
diff --git a/Framework/NexusGeometry/src/H5ForwardCompatibility.cpp b/Framework/NexusGeometry/src/H5ForwardCompatibility.cpp
deleted file mode 100644
index 5fcd50561d0c..000000000000
--- a/Framework/NexusGeometry/src/H5ForwardCompatibility.cpp
+++ /dev/null
@@ -1,64 +0,0 @@
-// Mantid Repository : https://github.com/mantidproject/mantid
-//
-// Copyright &copy; 2018 ISIS Rutherford Appleton Laboratory UKRI,
-//   NScD Oak Ridge National Laboratory, European Spallation Source,
-//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
-// SPDX - License - Identifier: GPL - 3.0 +
-#include "MantidNexusGeometry/H5ForwardCompatibility.h"
-#include <cstring> //memset.
-#include <string>
-
-namespace Mantid::NexusGeometry::H5ForwardCompatibility {
-
-/*
- * Function "getObjName"
- * Ported from newer versions of the HDF API for forward compatibility to
- * support HDF5 version < 1.8.13
- * https://portal.hdfgroup.org/display/HDF5/Software+Changes+from+Release+to+Release+for+HDF5-1.8
- */
-ssize_t getObjName(const H5::H5Object &obj, char *obj_name, size_t buf_size) {
-  // H5Iget_name will get buf_size-1 chars of the name to null terminate it
-  ssize_t name_size = H5Iget_name(obj.getId(), obj_name, buf_size);
-
-  // If H5Iget_name returns a negative value, raise an exception
-  if (name_size < 0) {
-    throw H5::Exception("getObjName", "H5Iget_name failed");
-  } else if (name_size == 0) {
-    throw H5::Exception("getObjName", "Object must have a name, but name length is 0");
-  }
-  // Return length of the name
-  return (name_size);
-}
-
-std::string getObjName(const H5::H5File &) { return "File Object"; }
-std::string getObjName(const H5::H5Object &obj) {
-  std::string obj_name; // object name to return
-
-  // Preliminary call to get the size of the object name
-  ssize_t name_size = H5Iget_name(obj.getId(), nullptr, static_cast<size_t>(0));
-
-  // If H5Iget_name failed, throw exception
-  if (name_size < 0) {
-    throw H5::Exception("getObjName", "H5Iget_name failed");
-  } else if (name_size == 0) {
-    throw H5::Exception("getObjName", "Object must have a name, but name length is 0");
-  }
-  // Object's name exists, retrieve it
-  else {
-    char *name_C = new char[name_size + 1]; // temporary C-string
-    memset(name_C, 0, name_size + 1);       // clear buffer
-
-    // Use overloaded function
-    getObjName(obj, name_C, name_size + 1);
-
-    // Convert the C object name to return
-    obj_name = name_C;
-
-    // Clean up resource
-    delete[] name_C;
-  }
-  // Return object's name
-  return (obj_name);
-}
-
-} // namespace Mantid::NexusGeometry::H5ForwardCompatibility
diff --git a/Framework/NexusGeometry/src/NexusGeometryParser.cpp b/Framework/NexusGeometry/src/NexusGeometryParser.cpp
index 24909b3ddd01..f7dc50b151f4 100644
--- a/Framework/NexusGeometry/src/NexusGeometryParser.cpp
+++ b/Framework/NexusGeometry/src/NexusGeometryParser.cpp
@@ -11,7 +11,6 @@
 #include "MantidGeometry/Rendering/ShapeInfo.h"
 #include "MantidKernel/ChecksumHelper.h"
 #include "MantidNexusGeometry/AbstractLogger.h"
-#include "MantidNexusGeometry/H5ForwardCompatibility.h"
 #include "MantidNexusGeometry/Hdf5Version.h"
 #include "MantidNexusGeometry/InstrumentBuilder.h"
 #include "MantidNexusGeometry/NexusGeometryDefinitions.h"
@@ -56,22 +55,22 @@ template <typename ExpectedT> void validateStorageType(const DataSet &data) {
     if (H5T_FLOAT != typeClass) {
       throw std::runtime_error("Storage type mismatch. Expecting to extract a "
                                "floating point number from " +
-                               H5_OBJ_NAME(data));
+                               data.getObjName());
     }
     if (sizeOfType != sizeof(ExpectedT)) {
       throw std::runtime_error("Storage type mismatch for floats. This operation "
                                "is dangerous. Nexus stored has byte size:" +
-                               std::to_string(sizeOfType) + " in " + H5_OBJ_NAME(data));
+                               std::to_string(sizeOfType) + " in " + data.getObjName());
     }
   } else if (std::is_integral<ExpectedT>::value) {
     if (H5T_INTEGER != typeClass) {
-      throw std::runtime_error("Storage type mismatch. Expecting to extract a integer from " + H5_OBJ_NAME(data));
+      throw std::runtime_error("Storage type mismatch. Expecting to extract a integer from " + data.getObjName());
     }
     if (sizeOfType > sizeof(ExpectedT)) {
       // endianness not checked
       throw std::runtime_error("Storage type mismatch for integer. Result "
                                "would result in truncation. Nexus stored has byte size:" +
-                               std::to_string(sizeOfType) + " in " + H5_OBJ_NAME(data));
+                               std::to_string(sizeOfType) + " in " + data.getObjName());
     }
   }
 }
@@ -130,7 +129,7 @@ class Parser {
       ints = get1DDataset<int64_t>(object, dsName);
     } else {
       std::stringstream ss;
-      ss << "Cannot handle reading ints of size " << nxintsize << " from " << dsName << " in " << H5_OBJ_NAME(object)
+      ss << "Cannot handle reading ints of size " << nxintsize << " from " << dsName << " in " << object.getObjName()
          << ". Only 64 and 32 bit signed ints handled";
       throw std::runtime_error(ss.str());
     }
@@ -149,7 +148,7 @@ class Parser {
       ints = convertVector<int64_t, uint32_t>(get1DDataset<int64_t>(object, dsName));
     } else {
       std::stringstream ss;
-      ss << "Cannot handle reading ints of size " << nxintsize << " from " << dsName << " in " << H5_OBJ_NAME(object)
+      ss << "Cannot handle reading ints of size " << nxintsize << " from " << dsName << " in " << object.getObjName()
          << ". Only 64 and 32 bit signed ints handled";
       throw std::runtime_error(ss.str());
     }
@@ -160,7 +159,7 @@ class Parser {
   typename std::enable_if<std::is_base_of<H5::H5Object, T>::value, std::string>::type
   unsupportedNXFloatMessage(size_t nxfloatsize, const T &object, const std::string &dsName) {
     std::stringstream ss;
-    ss << "Cannot handle reading ints of size " << nxfloatsize << " from " << dsName << " in " << H5_OBJ_NAME(object)
+    ss << "Cannot handle reading ints of size " << nxfloatsize << " from " << dsName << " in " << object.getObjName()
        << ". Only 64 and 32 bit floats handled";
     return ss.str();
   }
@@ -359,8 +358,7 @@ class Parser {
   Eigen::Transform<double, 3, Eigen::Affine> getTransformations(const H5File &file, const Group &detectorGroup) {
     H5std_string dependency;
     // Get absolute dependency path
-    auto status = H5Gget_objinfo(detectorGroup.getId(), DEPENDS_ON.c_str(), false, nullptr);
-    if (status == 0) {
+    if (detectorGroup.nameExists(DEPENDS_ON)) {
       dependency = get1DStringDataset(DEPENDS_ON, detectorGroup);
     } else {
       return Eigen::Transform<double, 3, Eigen::Affine>::Identity();
@@ -432,7 +430,7 @@ class Parser {
         transforms = rotation * transforms;
       } else {
         throw std::runtime_error("Unknown Transform type \"" + transformType + "\" found in " +
-                                 H5_OBJ_NAME(transformation) + " when parsing Nexus geometry");
+                                 transformation.getObjName() + " when parsing Nexus geometry");
       }
     }
     return transforms;
@@ -645,7 +643,7 @@ class Parser {
       parseNexusCylinderDetector(shapeGroup, bankName, builder, detectorIds);
     } else {
       std::stringstream ss;
-      ss << "Shape group " << H5_OBJ_NAME(shapeGroup) << " has unknown geometry type specified via " << NX_CLASS;
+      ss << "Shape group " << shapeGroup.getObjName() << " has unknown geometry type specified via " << NX_CLASS;
       throw std::runtime_error(ss.str());
     }
   }
@@ -738,7 +736,7 @@ class Parser {
     for (auto &detectorGroup : detectorGroups) {
       // Transform in homogenous coordinates. Offsets will be rotated then bank
       // translation applied.
-      auto debug = H5_OBJ_NAME(detectorGroup);
+      auto debug = detectorGroup.getObjName();
       Eigen::Transform<double, 3, 2> transforms = getTransformations(file, detectorGroup);
       // Absolute bank position
       Eigen::Vector3d bankPos = transforms * Eigen::Vector3d{0, 0, 0};
diff --git a/Framework/NexusGeometry/src/NexusGeometrySave.cpp b/Framework/NexusGeometry/src/NexusGeometrySave.cpp
index ea5cbc2798f4..e4a1e5f71c6a 100644
--- a/Framework/NexusGeometry/src/NexusGeometrySave.cpp
+++ b/Framework/NexusGeometry/src/NexusGeometrySave.cpp
@@ -22,7 +22,6 @@
 #include "MantidIndexing/IndexInfo.h"
 #include "MantidKernel/EigenConversionHelpers.h"
 #include "MantidKernel/ProgressBase.h"
-#include "MantidNexusGeometry/H5ForwardCompatibility.h"
 #include "MantidNexusGeometry/NexusGeometryDefinitions.h"
 #include "MantidNexusGeometry/NexusGeometryUtilities.h"
 #include <H5Cpp.h>
@@ -64,7 +63,7 @@ struct SpectraMappings {
  * @return : new H5 Group object with name <childGroupName> if did not throw.
  */
 inline H5::Group tryCreateGroup(const H5::Group &parentGroup, const std::string &childGroupName) {
-  H5std_string parentGroupName = H5_OBJ_NAME(parentGroup);
+  H5std_string parentGroupName = parentGroup.getObjName();
   for (hsize_t i = 0; i < parentGroup.getNumObjs(); ++i) {
     if (parentGroup.getObjTypeByIdx(i) == GROUP_TYPE) {
       H5std_string child = parentGroup.getObjnameByIdx(i);
@@ -239,7 +238,7 @@ void writeXYZPixeloffset(H5::Group &grp, const Geometry::ComponentInfo &compInfo
   hsize_t dims[static_cast<hsize_t>(1)];
   dims[0] = nDetectorsInBank;
 
-  H5::DataSpace space = H5Screate_simple(rank, dims, nullptr);
+  H5::DataSpace space = H5::DataSpace(rank, dims, nullptr);
 
   if (!xIsZero) {
     xPixelOffset = grp.createDataSet(X_PIXEL_OFFSET, H5::PredType::NATIVE_DOUBLE, space);
@@ -265,7 +264,7 @@ void write1DIntDataset(H5::Group &grp, const H5std_string &name, const std::vect
   const int rank = 1;
   hsize_t dims[1] = {static_cast<hsize_t>(container.size())};
 
-  H5::DataSpace space = H5Screate_simple(rank, dims, nullptr);
+  H5::DataSpace space = H5::DataSpace(rank, dims, nullptr);
 
   auto dataset = grp.createDataSet(name, H5::PredType::NATIVE_INT, space);
   if (!container.empty())
@@ -340,7 +339,7 @@ void writeNXMonitorNumber(H5::Group &grp, const int monitorID) {
   hsize_t dims[static_cast<hsize_t>(1)];
   dims[0] = static_cast<hsize_t>(1);
 
-  H5::DataSpace space = H5Screate_simple(rank, dims, nullptr);
+  H5::DataSpace space = H5::DataSpace(rank, dims, nullptr);
 
   // these DataSets are duplicates of each other. written to the group to
   // handle the naming inconsistency. probably temporary.
@@ -388,7 +387,7 @@ inline void writeLocation(H5::Group &grp, const Eigen::Vector3d &position) {
   auto unitVec = position.normalized();                  // unit vector of the position vector
   std::vector<double> stdNormPos = toStdVector(unitVec); // convert to std::vector
 
-  dspace = H5Screate_simple(drank, ddims, nullptr); // dataspace for dataset
+  dspace = H5::DataSpace(drank, ddims, nullptr); // dataspace for dataset
   location = grp.createDataSet(LOCATION, H5::PredType::NATIVE_DOUBLE,
                                dspace); // dataset location
   location.write(&norm, H5::PredType::NATIVE_DOUBLE,
@@ -398,7 +397,7 @@ inline void writeLocation(H5::Group &grp, const Eigen::Vector3d &position) {
   hsize_t adims[static_cast<hsize_t>(3)]; // dimensions of attribute
   adims[0] = 3;                           // datapoints in attribute dimension 0
 
-  aspace = H5Screate_simple(arank, adims, nullptr); // dataspace for attribute
+  aspace = H5::DataSpace(arank, adims, nullptr); // dataspace for attribute
   vector = location.createAttribute(VECTOR, H5::PredType::NATIVE_DOUBLE,
                                     aspace); // attribute vector
   vector.write(H5::PredType::NATIVE_DOUBLE,
@@ -459,7 +458,7 @@ inline void writeOrientation(H5::Group &grp, const Eigen::Quaterniond &rotation,
   Eigen::Vector3d axisOfRotation = rotation.vec().normalized();  // angle axis
   std::vector<double> stdNormAxis = toStdVector(axisOfRotation); // convert to std::vector
 
-  dspace = H5Screate_simple(drank, ddims, nullptr); // dataspace for dataset
+  dspace = H5::DataSpace(drank, ddims, nullptr); // dataspace for dataset
   orientation = grp.createDataSet(ORIENTATION, H5::PredType::NATIVE_DOUBLE,
                                   dspace); // dataset orientation
   orientation.write(&angle, H5::PredType::NATIVE_DOUBLE,
@@ -469,7 +468,7 @@ inline void writeOrientation(H5::Group &grp, const Eigen::Quaterniond &rotation,
   hsize_t adims[static_cast<hsize_t>(3)]; // dimensions of attribute
   adims[0] = static_cast<hsize_t>(3);     // datapoints in attibute dimension 0
 
-  aspace = H5Screate_simple(arank, adims, nullptr); // dataspace for attribute
+  aspace = H5::DataSpace(arank, adims, nullptr); // dataspace for attribute
   vector = orientation.createAttribute(VECTOR, H5::PredType::NATIVE_DOUBLE,
                                        aspace); // attribute vector
   vector.write(H5::PredType::NATIVE_DOUBLE,
@@ -699,17 +698,17 @@ class NexusGeometrySaveImpl {
       // neither orientation nor location are non-zero, NXsource is self
       // dependent.
       if (!locationIsOrigin) {
-        dependency = H5_OBJ_NAME(transformations) + "/" + LOCATION;
+        dependency = transformations.getObjName() + "/" + LOCATION;
         writeLocation(transformations, position);
       }
       if (!orientationIsZero) {
-        dependency = H5_OBJ_NAME(transformations) + "/" + ORIENTATION;
+        dependency = transformations.getObjName() + "/" + ORIENTATION;
 
         // If location dataset is written to group also, then dependency for
         // orientation dataset containg the rotation transformation will be
         // location. Else dependency for orientation is self.
         std::string rotationDependency =
-            locationIsOrigin ? NO_DEPENDENCY : H5_OBJ_NAME(transformations) + "/" + LOCATION;
+            locationIsOrigin ? NO_DEPENDENCY : transformations.getObjName() + "/" + LOCATION;
         writeOrientation(transformations, rotation, rotationDependency);
       }
     }
@@ -762,17 +761,17 @@ class NexusGeometrySaveImpl {
       // If neither orientation nor location are non-zero, NXmonitor is self
       // dependent.
       if (!locationIsOrigin) {
-        dependency = H5_OBJ_NAME(transformations) + "/" + LOCATION;
+        dependency = transformations.getObjName() + "/" + LOCATION;
         writeLocation(transformations, position);
       }
       if (!orientationIsZero) {
-        dependency = H5_OBJ_NAME(transformations) + "/" + ORIENTATION;
+        dependency = transformations.getObjName() + "/" + ORIENTATION;
 
         // If location dataset is written to group also, then dependency for
         // orientation dataset containg the rotation transformation will be
         // location. Else dependency for orientation is self.
         std::string rotationDependency =
-            locationIsOrigin ? NO_DEPENDENCY : H5_OBJ_NAME(transformations) + "/" + LOCATION;
+            locationIsOrigin ? NO_DEPENDENCY : transformations.getObjName() + "/" + LOCATION;
         writeOrientation(transformations, rotation, rotationDependency);
       }
     }
@@ -859,17 +858,17 @@ class NexusGeometrySaveImpl {
       // If neither orientation nor location are non-zero, NXdetector is self
       // dependent.
       if (!locationIsOrigin) {
-        dependency = H5_OBJ_NAME(transformations) + "/" + LOCATION;
+        dependency = transformations.getObjName() + "/" + LOCATION;
         writeLocation(transformations, position);
       }
       if (!orientationIsZero) {
-        dependency = H5_OBJ_NAME(transformations) + "/" + ORIENTATION;
+        dependency = transformations.getObjName() + "/" + ORIENTATION;
 
         // If location dataset is written to group also, then dependency for
         // orientation dataset containing the rotation transformation will be
         // location. Else dependency for orientation is self.
         std::string rotationDependency =
-            locationIsOrigin ? NO_DEPENDENCY : H5_OBJ_NAME(transformations) + "/" + LOCATION;
+            locationIsOrigin ? NO_DEPENDENCY : transformations.getObjName() + "/" + LOCATION;
         writeOrientation(transformations, rotation, rotationDependency);
       }
     }
diff --git a/Framework/NexusGeometry/src/NexusGeometryUtilities.cpp b/Framework/NexusGeometry/src/NexusGeometryUtilities.cpp
index 895ab36768ae..7a1907c7ba37 100644
--- a/Framework/NexusGeometry/src/NexusGeometryUtilities.cpp
+++ b/Framework/NexusGeometry/src/NexusGeometryUtilities.cpp
@@ -5,7 +5,6 @@
 //   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
 // SPDX - License - Identifier: GPL - 3.0 +
 #include "MantidNexusGeometry/NexusGeometryUtilities.h"
-#include "MantidNexusGeometry/H5ForwardCompatibility.h"
 #include "MantidNexusGeometry/NexusGeometryDefinitions.h"
 #include <regex>
 namespace Mantid::NexusGeometry::utilities {
@@ -66,7 +65,7 @@ bool hasNXClass(const H5::Group &group, const std::string &attributeValue) {
 }
 
 bool isNamed(const H5::H5Object &object, const std::string &name) {
-  const auto objName = H5_OBJ_NAME(object);
+  const auto objName = object.getObjName();
   // resultName gives full path. We match the last name on the path
   return std::regex_match(objName, std::regex(".*/" + name + "$"));
 }
diff --git a/Framework/TestHelpers/inc/MantidFrameworkTestHelpers/NexusFileReader.h b/Framework/TestHelpers/inc/MantidFrameworkTestHelpers/NexusFileReader.h
index e5371d3da181..47a6cb3b6827 100644
--- a/Framework/TestHelpers/inc/MantidFrameworkTestHelpers/NexusFileReader.h
+++ b/Framework/TestHelpers/inc/MantidFrameworkTestHelpers/NexusFileReader.h
@@ -6,7 +6,6 @@
 // SPDX - License - Identifier: GPL - 3.0 +
 #pragma once
 
-#include "MantidNexusGeometry/H5ForwardCompatibility.h"
 #include "MantidNexusGeometry/NexusGeometryDefinitions.h"
 
 #include <Eigen/Dense>

From 70ca9e48da990965773fdb2410bd81f4273345e0 Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Tue, 21 Jan 2025 10:34:13 +1100
Subject: [PATCH 5/9] Update NexusHDF5Descriptor

---
 Framework/Kernel/src/NexusHDF5Descriptor.cpp | 157 +++----------------
 1 file changed, 26 insertions(+), 131 deletions(-)

diff --git a/Framework/Kernel/src/NexusHDF5Descriptor.cpp b/Framework/Kernel/src/NexusHDF5Descriptor.cpp
index dfe20186ee02..dde98bce2d1e 100644
--- a/Framework/Kernel/src/NexusHDF5Descriptor.cpp
+++ b/Framework/Kernel/src/NexusHDF5Descriptor.cpp
@@ -10,8 +10,7 @@
 #include <boost/multi_index/detail/index_matcher.hpp>
 
 #include "MantidKernel/NexusDescriptor.h"
-
-#include <hdf5.h>
+#include <H5Cpp.h>
 
 #include <cstdlib>   // malloc, calloc
 #include <cstring>   // strcpy
@@ -26,144 +25,43 @@ namespace Mantid::Kernel {
 /// PRIVATE
 namespace {
 
-/**
- * populate a string attribute from HDF5 attribute handler
- * @param attr input HDF5 atttribute handler
- * @param data
- * @return
- */
-herr_t readStringAttribute(hid_t attr, char **data) {
-  herr_t iRet = 0;
-  hsize_t thedims[H5S_MAX_RANK];
-
-  hid_t atype = H5Aget_type(attr);
-  hsize_t sdim = H5Tget_size(atype);
-  hid_t space = H5Aget_space(attr);
-  int ndims = H5Sget_simple_extent_dims(space, thedims, NULL);
-
-  if (ndims == 0) {
-    if (H5Tis_variable_str(atype)) {
-      hid_t btype = H5Tget_native_type(atype, H5T_DIR_ASCEND);
-      iRet = H5Aread(attr, btype, data);
-      H5Tclose(btype);
-    } else {
-      *data = (char *)malloc(sdim + 1);
-      iRet = H5Aread(attr, atype, *data);
-      (*data)[sdim] = '\0';
-    }
-  } else if (ndims == 1) {
-    unsigned int i;
-    char **strings;
-
-    strings = (char **)malloc(thedims[0] * sizeof(char *));
-
-    if (!H5Tis_variable_str(atype)) {
-      strings[0] = (char *)malloc(thedims[0] * sdim * sizeof(char));
-      for (i = 1; i < thedims[0]; i++) {
-        strings[i] = strings[0] + i * sdim;
-      }
-    }
-
-    iRet = H5Aread(attr, atype, strings[0]);
-    *data = (char *)calloc((sdim + 2) * thedims[0], sizeof(char));
-    for (i = 0; i < thedims[0]; i++) {
-      if (i == 0) {
-        strncpy(*data, strings[i], sdim);
-      } else {
-        strcat(*data, ", ");
-        strncat(*data, strings[i], sdim);
-      }
-    }
-    if (H5Tis_variable_str(atype)) {
-      H5Dvlen_reclaim(atype, space, H5P_DEFAULT, strings);
-    } else {
-      free(strings[0]);
-    }
-
-    free(strings);
-  } else {
-    *data = (char *)malloc(33);
-    strcpy(*data, " higher dimensional string array\0");
-  }
-
-  H5Tclose(atype);
-  H5Sclose(space);
-  if (iRet < 0)
-    return -1;
-  return 0;
-}
-
-/**
- * Reads a string attribute of N-dimensions
- * @param attr input HDF5 attribute handler
- * @return
- */
-std::pair<std::string, herr_t> readStringAttributeN(hid_t attr) {
-  char *vdat = NULL;
-  const auto iRet = readStringAttribute(attr, &vdat);
-  std::string attrData;
-  if (iRet >= 0) {
-    attrData = vdat;
-  }
-  free(vdat);
-  return std::make_pair(attrData, iRet);
-}
-
-void getGroup(hid_t groupID, std::map<std::string, std::set<std::string>> &allEntries) {
+void getGroup(H5::Group groupID, std::map<std::string, std::set<std::string>> &allEntries) {
 
   /**
    * Return the NX_class attribute associate with objectName group entry
    */
-  auto lf_getNxClassAttribute = [&](hid_t groupID, const char *objectName) -> std::string {
+  auto lf_getNxClassAttribute = [&](H5::Group groupID) -> std::string {
     std::string attribute = "";
-    hid_t attributeID = H5Aopen_by_name(groupID, objectName, "NX_class", H5P_DEFAULT, H5P_DEFAULT);
-    if (attributeID < 0) {
-      H5Aclose(attributeID);
-      return attribute;
-    }
 
-    auto pairData = readStringAttributeN(attributeID);
-    // already null terminated in readStringAttributeN
-    attribute = pairData.first;
-    H5Aclose(attributeID);
+    if (groupID.attrExists("NX_class")) {
+      const auto attributeID = groupID.openAttribute("NX_class");
+      attributeID.read(attributeID.getDataType(), attribute);
+    }
 
     return attribute;
   };
 
-  // using HDF5 C API
-  constexpr std::size_t maxLength = 1024;
-  char groupName[maxLength];
-  char memberName[maxLength];
-  std::size_t groupNameLength = static_cast<std::size_t>(H5Iget_name(groupID, groupName, maxLength));
-  hsize_t nObjects = 0;
-  H5Gget_num_objs(groupID, &nObjects);
-
-  const std::string groupNameStr(groupName, groupNameLength);
-  const std::string nxClass = (groupNameStr == "/") ? "" : lf_getNxClassAttribute(groupID, groupNameStr.c_str());
+  // using HDF5 C++ API
+  const std::string groupNameStr = groupID.getObjName();
+  const std::string nxClass = (groupNameStr == "/") ? "" : lf_getNxClassAttribute(groupID);
 
   if (!nxClass.empty()) {
     allEntries[nxClass].insert(groupNameStr);
   }
 
-  for (unsigned int i = 0; i < nObjects; ++i) {
+  for (hsize_t i = 0; i < groupID.getNumObjs(); ++i) {
 
-    const int type = H5Gget_objtype_by_idx(groupID, static_cast<size_t>(i));
-    const std::size_t memberNameLength =
-        static_cast<std::size_t>(H5Gget_objname_by_idx(groupID, static_cast<hsize_t>(i), memberName, maxLength));
-
-    if (type == H5O_TYPE_GROUP) {
-      hid_t subGroupID = H5Gopen2(groupID, memberName, H5P_DEFAULT);
+    H5G_obj_t type = groupID.getObjTypeByIdx(i);
+    H5std_string memberName = groupID.getObjnameByIdx(i);
+    if (type == H5G_GROUP) {
+      H5::Group subGroupID = groupID.openGroup(memberName);
       getGroup(subGroupID, allEntries);
-      H5Gclose(subGroupID);
-
-    } else if (type == H5O_TYPE_DATASET) {
-      const std::string memberNameStr(memberName, memberNameLength);
-      const std::string absoluteEntryName = groupNameStr + "/" + memberNameStr;
+    } else if (type == H5G_DATASET) {
+      const std::string absoluteEntryName = groupNameStr + "/" + memberName;
       allEntries["SDS"].insert(absoluteEntryName);
     }
   }
 }
-
 } // namespace
 
 bool NexusHDF5Descriptor::isReadable(const std::string &filename) {
@@ -183,24 +81,21 @@ const std::map<std::string, std::set<std::string>> &NexusHDF5Descriptor::getAllE
 
 // PRIVATE
 std::map<std::string, std::set<std::string>> NexusHDF5Descriptor::initAllEntries() {
-
-  hid_t fapl = H5Pcreate(H5P_FILE_ACCESS);
-  H5Pset_fclose_degree(fapl, H5F_CLOSE_STRONG);
-
-  hid_t fileID = H5Fopen(m_filename.c_str(), H5F_ACC_RDONLY, fapl);
-  if (fileID < 0) {
-
-    throw std::invalid_argument("ERROR: Kernel::NexusHDF5Descriptor couldn't open hdf5 file " + m_filename +
-                                " with fapl " + std::to_string(fapl) + "\n");
+  H5::FileAccPropList access_plist;
+  access_plist.setFcloseDegree(H5F_CLOSE_STRONG);
+
+  H5::H5File fileID;
+  try {
+    fileID = H5::H5File(m_filename, H5F_ACC_RDONLY, H5::FileCreatPropList::DEFAULT, access_plist);
+  } catch (const H5::FileIException &) {
+    throw std::invalid_argument("ERROR: Kernel::NexusHDF5Descriptor couldn't open hdf5 file " + m_filename + "\n");
   }
 
-  hid_t groupID = H5Gopen2(fileID, "/", H5P_DEFAULT);
+  H5::Group groupID = fileID.openGroup("/");
 
   std::map<std::string, std::set<std::string>> allEntries;
   // scan file recursively starting with root group "/"
   getGroup(groupID, allEntries);
-  H5Gclose(groupID);
-  H5Fclose(fileID);
 
   // rely on move semantics
   return allEntries;

From 143249f8a7243a66be37d877f222ce32878334ef Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Tue, 21 Jan 2025 13:19:50 +1100
Subject: [PATCH 6/9] Update CppCheck_Suppressions

---
 buildconfig/CMake/CppCheck_Suppressions.txt.in | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/buildconfig/CMake/CppCheck_Suppressions.txt.in b/buildconfig/CMake/CppCheck_Suppressions.txt.in
index 36fe47cfe509..ac473e16c11e 100644
--- a/buildconfig/CMake/CppCheck_Suppressions.txt.in
+++ b/buildconfig/CMake/CppCheck_Suppressions.txt.in
@@ -826,11 +826,6 @@ truncLongCastAssignment:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/Matrix.cpp:1021
 suspiciousFloatingPointCast:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/Matrix.cpp:1205
 iterateByValue:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/MultiFileValidator.cpp:65
 constVariablePointer:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/NeutronAtom.cpp:713
-cstyleCast:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/NexusHDF5Descriptor.cpp:50
-cstyleCast:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/NexusHDF5Descriptor.cpp:58
-cstyleCast:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/NexusHDF5Descriptor.cpp:61
-cstyleCast:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/NexusHDF5Descriptor.cpp:68
-cstyleCast:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/NexusHDF5Descriptor.cpp:85
 variableScope:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/PropertyManager.cpp:113
 invalidLifetime:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/PropertyManager.cpp:142
 constVariablePointer:${CMAKE_SOURCE_DIR}/Framework/Kernel/src/PropertyManager.cpp:158

From 5ad9c14593ebc5ce6f41a5165f0c2997ce4306f3 Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Tue, 21 Jan 2025 14:08:03 +1100
Subject: [PATCH 7/9] Fix error: reference to 'Exception' is ambiguous

---
 Framework/DataHandling/test/LoadNexusProcessedTest.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/Framework/DataHandling/test/LoadNexusProcessedTest.h b/Framework/DataHandling/test/LoadNexusProcessedTest.h
index a6cb5421bcf4..6c3e14a184b8 100644
--- a/Framework/DataHandling/test/LoadNexusProcessedTest.h
+++ b/Framework/DataHandling/test/LoadNexusProcessedTest.h
@@ -49,8 +49,6 @@ using namespace Mantid::HistogramData;
 using namespace Mantid::NeXus;
 using Mantid::detid_t;
 
-using namespace H5;
-
 // Note that this suite tests an old version of Nexus processed files that we
 // continue to support.
 // LoadRawSaveNxsLoadNxs tests the current version of Nexus processed by loading
@@ -801,7 +799,7 @@ class LoadNexusProcessedTest : public CxxTest::TestSuite {
 
     // Remove the coordinate_system entry so it falls back on the log. NeXus
     // can't do this so use the HDF5 API directly
-    H5File h5file(filePath.c_str(), H5F_ACC_RDWR);
+    H5::H5File h5file(filePath.c_str(), H5F_ACC_RDWR);
     H5Util::deleteObjectLink(h5file, "/mantid_workspace_1/peaks_workspace/coordinate_system");
     h5file.close();
 

From 48d482b7ff6a9efe0ccc2d79b21f384d191bf5b6 Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Tue, 21 Jan 2025 16:02:10 +1100
Subject: [PATCH 8/9] Fix unreferenced local variable warning

---
 Framework/DataHandling/src/LoadSassena.cpp | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Framework/DataHandling/src/LoadSassena.cpp b/Framework/DataHandling/src/LoadSassena.cpp
index 23eb94d0705d..acb2043c1dcf 100644
--- a/Framework/DataHandling/src/LoadSassena.cpp
+++ b/Framework/DataHandling/src/LoadSassena.cpp
@@ -101,7 +101,7 @@ HistogramData::Points LoadSassena::loadQvectors(const H5::H5File &h5file, const
   hsize_t dims[3];
   try {
     dataSetInfo(h5file, setName, dims);
-  } catch (H5::Exception &e) {
+  } catch (H5::Exception &) {
     throw Kernel::Exception::FileError("Unable to read " + setName + " dataset info:", m_filename);
   }
 
@@ -110,7 +110,7 @@ HistogramData::Points LoadSassena::loadQvectors(const H5::H5File &h5file, const
 
   try {
     this->dataSetDouble(h5file, "qvectors", buf);
-  } catch (H5::Exception &e) {
+  } catch (H5::Exception &) {
     this->g_log.error("LoadSassena::loadQvectors cannot proceed");
     qvmod.resize(0);
     return HistogramData::Points(std::move(qvmod));
@@ -169,7 +169,7 @@ void LoadSassena::loadFQ(const H5::H5File &h5file, const API::WorkspaceGroup_spt
   std::vector<double> buf(nq * 2);
   try {
     this->dataSetDouble(h5file, setName, buf);
-  } catch (H5::Exception &e) {
+  } catch (H5::Exception &) {
     this->g_log.error("LoadSassena::loadFQ cannot proceed");
     return;
   }
@@ -229,7 +229,7 @@ void LoadSassena::loadFQT(const H5::H5File &h5file, const API::WorkspaceGroup_sp
   std::vector<double> buf(nq * nnt * 2);
   try {
     this->dataSetDouble(h5file, setName, buf);
-  } catch (H5::Exception &e) {
+  } catch (H5::Exception &) {
     this->g_log.error("LoadSassena::loadFQT cannot proceed");
     return;
   }
@@ -356,7 +356,7 @@ void LoadSassena::exec() {
   H5::H5File h5file;
   try {
     h5file = H5::H5File(m_filename.c_str(), H5F_ACC_RDONLY);
-  } catch (H5::FileIException &e) {
+  } catch (H5::FileIException &) {
     this->g_log.error("Cannot open " + m_filename);
     throw Kernel::Exception::FileError("Unable to open:", m_filename);
   }

From 3359aa9b32c1ba8469784aa88d048bcb2a9b4e36 Mon Sep 17 00:00:00 2001
From: Ross Whitfield <whitfieldre1@ornl.gov>
Date: Wed, 22 Jan 2025 08:19:12 +1100
Subject: [PATCH 9/9] this

---
 Framework/DataHandling/src/LoadSassena.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Framework/DataHandling/src/LoadSassena.cpp b/Framework/DataHandling/src/LoadSassena.cpp
index acb2043c1dcf..f7510cee7f22 100644
--- a/Framework/DataHandling/src/LoadSassena.cpp
+++ b/Framework/DataHandling/src/LoadSassena.cpp
@@ -100,7 +100,7 @@ HistogramData::Points LoadSassena::loadQvectors(const H5::H5File &h5file, const
 
   hsize_t dims[3];
   try {
-    dataSetInfo(h5file, setName, dims);
+    this->dataSetInfo(h5file, setName, dims);
   } catch (H5::Exception &) {
     throw Kernel::Exception::FileError("Unable to read " + setName + " dataset info:", m_filename);
   }
@@ -216,7 +216,7 @@ void LoadSassena::loadFQT(const H5::H5File &h5file, const API::WorkspaceGroup_sp
 
   hsize_t dims[3];
   try {
-    dataSetInfo(h5file, setName, dims);
+    this->dataSetInfo(h5file, setName, dims);
   } catch (H5::Exception &) {
     this->g_log.error("Unable to read " + setName + " dataset info");
     this->g_log.error("LoadSassena::loadFQT cannot proceed");