[gmx-developers] preprocessing bug or feature?

David van der Spoel spoel at xray.bmc.uu.se
Tue Apr 28 18:49:39 CEST 2009

Martin Höfling wrote:
> 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?

There is no reason to support the entire standard, (I have not even 
looked at it). However there is an open bugzilla about the preprocessor, 
you can add your comment to it, then I will try to fix it before 4.1.

> If not, maybe some extra warning about these whitespaces can avoid 
> searching at the wrong place.
> Best
>     Martin
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David van der Spoel, PhD, Professor of Biology
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://folding.bmc.uu.se

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