[CMake] find_library can't find dll in system32 directory

[Stiaan Gerber]

Hi all

On 64-bit Windows 7

I am trying to use the find_library command to locate a 64-bit mpich2
dll in the C:/Windows/System32 directory. I use

find_library (MPI_LIB fmpich2g PATHS "C:/Windows/System32")

This command fails to find the dll. However, if I also install 32-bit
mpich2 so that C:/Windows/SysWOW64/fmpich2g.dll exists,
the command works and MPI_LIB is set to C:/Windows/System32/fmpich2g.dll
which is actually my 64-bit dll.

So the way I see it, find_library can only "find" my 64-bit dll if a
corresponding 32-bit dll is present. I have seen a previous thread on
this subject (http://www.mail-archive.com/cmake@cmake.org/msg29248.html)
which explains that Windows actually reports the path
of the 32-bit dll as C:/Windows/System32, but this does not solve my
problem:

How do I correctly find the 64-bit version of a dll in
C:/Windows/System32 without the 32-bit dll existing?

Any insights would be much appreciated.

Kind regards
Stiaan Gerber