[gmx-developers] preprocessing bug or feature?

[Martin Höfling]

Hey Folks,

from what I remember gromacs previously used cpp to generate a file or  
line array including all the other included files. I stumbled upon a  
problem when I tried to use topologies from sb. else, probably used on  
older gromacs versions:

if you:

# define blubb

instead of

#define blubb
(without whitespace)

then cpp creates the "correct" output while grompp -pp does not. I  
attached a simple example and the cpped and grompped output.

In principal one would expect cpp and grompp -pp output to be more or  
less the same right? Is this extra whitspace  compliant with  
preprocessing language standard?

If not, maybe some extra warning about these whitespaces can avoid  
searching at the wrong place.

Best
	Martin