gmxcpp does not support #elif
gmxcpp does not support #elif.
I think no other directives are missing,
but this should be checked with the cpp specifications.
#2 Updated by David van der Spoel about 10 years ago
I looked into both these feature requests. The inclusion of the elif would require code to move away from the simple stack algorithm, and hence complicate the source with the risk for new bugs. Since there is the simple workaround of having a additional (nested) #ifdef #endif pair, inclusion of elif does not seem justified.
The use of # XXX conditionals likewise would make the code harder to understand
Instead I have added a complete description of all options to the grompp -h output. Let's remember that the reason to have this in the code is to be able to run grompp on e.g. Crays, and other machines without compilers (even Linux cluster nodes often don't have it).