For your information: I've submitted below bug report to help@hdfgroup.org.

Maybe it makes sense to create symlinks from either /usr/include/static/*.mod or /usr/include/share/*.mod to /usr/include, but that would be in my eyes just a workaround for a bug that should be fixed upstream. Don't know if that is good practice.

VERSION:
HDF5-1.10.3

USER:
Martin Diehl, m.diehl@mpie.de

SYNOPSIS:
location of module files (Fortran) non-standard

MACHINE / OPERATING SYSTEM:
Arch Linux
Linux quadcore 4.18.4-arch1-1-ARCH #1 SMP PREEMPT Wed Aug 22
07:33:26 UTC 2018 x86_64 GNU/Linux

COMPILER:
GCC 8.2

DESCRIPTION:
The standard search location for Fortran module files (*.mod,
similar use as header files in C) is /usr/include. With the current
builds, the HDF5 module files are stored in /usr/include/static and
/usr/include/shared. When compiling my application, they are therefore
not found. This behaviour seems especially unreasonable to me as there
is (and to my knowledge) will never be a difference between the static
and shared version because the *.mod files are directly generated from
the source code. The only possible way to have different shared and
static *.mod files would be the use of different versions of HDF5 for
static and shared libraries. But that seems to be the first step to a
version hell, so in my opinion one should not support such setups by
default, especially at the cost that more standard setups are not
working anymore

REPEAT BUG BY:
- unpack current archive "hdf5-1.10.3.tar.bz2"
- create a directory "build" in "hdf5-1.10.3" and cd into it
- run: CXX="mpicxx" CC="mpicc" FC="mpif90" F9X="mpif90"
RUNPARALLEL="mpirun" OMPI_MCA_disable_memory_allocator=1 cmake ..
-DCMAKE_INSTALL_PREFIX=/tmp -DBUILD_SHARED_LIBS=ON
-DCMAKE_BUILD_TYPE=Release -DALLOW_UNSUPPORTED=ON
-DHDF5_BUILD_HL_LIB=ON -DHDF5_BUILD_CPP_LIB=ON -DHDF5_BUILD_FORTRAN=ON
-DHDF5_ENABLE_PARALLEL=ON
- run: cmake --build . --config Release
- run: make DESTDIR=/ install

SAMPLE FIX:
N/A