Declare cctkGH as "const cGH*"

[Erik Schnetter]

cctkGH is declared as "const cGH" in several places, but DECLARE_CCTK_ARGUMENTS still declares it only as "cGH". This should be changed.

I checked, and some thorns need updating to deal with this. I propose to make this change after the release.

Keyword:

[Roland Haas]

I have no objections to such a change. There is nothing to review in the ticket though.

[Erik Schnetter]

This is a one-line change in GridFuncStuff.pl, line 912, adding the respective "const" declaration.

Unfortunately, this change creates a lot of fallout. Many infrastructure thorns (driver, coordinates, I/O) change cctkGH, and would all have to cast away this const declaration. I'm not sure this is worth the effort.

Also, since this casting-away is legal in this case, compilers cannot use this const declaration to optimize code. (I did not know this before.)

[Ian Hinder]

Should this be closed as "wontfix"? In theory, making things safer for application thorns would be worth adding a bit of complexity to infrastructure thorns, but if it's too much work, then we can just leave it as is.

[Erik Schnetter]

The long-term fix would be to encapsulate the cctkGH fields properly so that they don't have to be set explicitly. I'm leaning towards leaving this as "won't fix".