If your code is standard-conforming, you will have minimal problems in porting the program to various platforms. By creating a configuration file that is the intersection of the language extensions available among all the platforms you support, portability violations can be flagged with ease. Platform-specific code is analyzed correctly, since cpp-like preprocessing is supported by Coverity Fortran Syntax Analysis.
Some types can be different on the various platforms. In that case, consistent analysis will require the creation of a different configuration file for those different platforms.
Coverity Fortran Syntax Analysis presents a warning if you use an implicit type in one place in the code and the explicit type in another, e.g. when associating arguments, because that implies a portability risk.