When compiling the toolkit using the bundled version of the HDF5 library, the thorn fails to compile and blocks the rest of the compilation process.
Specifically, the main library, distributed as "hdf5-1.12.0.tar.gz" compiles fine but the additional component "h5check_2_0.tar.gz" fails to build (using gcc 8.3) due to multiple definitions of the type "error_t". It seams that h5check defines this type which conflicts with cstdlib's own error_t.
Since this type is used in only three places, I've managed to fix the bug by replacing "error_t" in the source files with "h5_error_t". I'm sending the "corrected" source file attached.
I've observed the bug in release 2020/05 but I think that any release that uses h5check version 1.12.0 may also show this behavior