Hello all,
thank you for noticing this!
In other words, strings can now be longer than 2e9 characters. This is a good change. To make this possible, the length of strings is now passed as ptrdiff_t instead of as int, and consequently, the C/Fortran interoperability mechanism in Cactus may need to be updated. Without this, there might be a segfault e.g. when calling CCTK_INFO from Fortran. (It might also be that things just work most of the time, although this would be an unreliable coincidence.)
I expect that they (unfortunately) probably work most of the time since on a little endian machine (ie a Intel sytem) both a ptrdiff_t and an int will have the same first 4 bytes on the stack (and likely the next four bytes are zero given that zero is the most common value for any byte) and the string length is the last argument on the stack so its incorrect size is not visible due to eg other arguments having the wrong location.
Something similar to this happened before when we forgot to properly declare strdup() in code which led to it being implicitly declared to return an int which is then cast to char* which actually often worked (namely whenever the returned address what less than 2GB).
So we need to carefully check the Cactus code to see what it assumes about the string passing convention.
Yours, Roland