On windows I found an issue with Visual studio where intel fortran was attempting to preprocess lowercase .f90 files. Intel's documentation states that it does not preprocess these files. Looking into the cmake source code I found:
in Modules/Platform/Windows-Intel-Fortran line 3:
set(_COMPILE_Fortran " /fpp")
which looks to me like cmake is adding this flag by default to all fortran files not .F90 vs .f90. Also we are using our own preprocessor which would also complicate things. Can you guys remove the setting of this flag?