For some reason, the check for H5free() was never added to CMakeLists.txt.  This becomes an issue with newer compilers, as observed in Ubuntu 18.04 and HDF5 1.10.2.  The issue isn't seen in HDF 1.8.20.
@@ -735,6 +735,7 @@ IF(USE_HDF5 OR ENABLE_NETCDF_4)
ENDIF()
CHECK_LIBRARY_EXISTS(${HDF5_C_LIBRARY_hdf5} H5Pset_libver_bounds "" HDF5_HAS_LIBVER_BOUNDS)
+ CHECK_LIBRARY_EXISTS(${HDF5_C_LIBRARY_hdf5} H5free_memory "" HDF5_HAS_H5FREE)
IF(HDF5_PARALLEL)
SET(HDF5_CC h5pcc)
