Writing the coordination with openACC about plumed2 HOT 3 OPEN

Regarding the vector and tensor with generic type, I tried to do the same a few years ago and I remember that with intel compiler the performances were measurably affected (to my surprise). Maybe you can double check this. In case it's true, maybe we can duplicate the code. Otherwise I am also happy with a more general version, it would be useful in other parts of the code as well

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(I have to try to make everything run compiled with plain nvhpc
But since nvhpc does not like the kw auto for deducing return types (as used in tools/MergeVectorTools.h:54), it needs some massages to the plumed source and I did not want to touch src for this project)

If it's limited to this maybe we can adjust the code. It would be ideal if we could also install nvc++ on one job in GitHub actions to test for this

from plumed2.

Regarding the vector and tensor with generic type, I tried to do the same a few years ago and I remember that with intel compiler the performances were measurably affected (to my surprise). Maybe you can double check this. In case it's true, maybe we can duplicate the code. Otherwise I am also happy with a more general version, it would be useful in other parts of the code as well

Ok, so I set up the PR as a wip, then I will produce some benchmarks

If it's limited to this maybe we can adjust the code. It would be ideal if we could also install nvc++ on one job in GitHub actions to test for this

I'm trying to do it in #1076

from plumed2.