[Bug fortran/64432] [5 Regression] SYSTEM_CLOCK(COUNT_RATE=rate) wrong result for integer(4)::rate

[fxcoudert at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64432

Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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           Assignee|unassigned at gcc dot gnu.org      |fxcoudert at gcc dot gnu.org

--- Comment #4 from Francois-Xavier Coudert <fxcoudert at gcc dot gnu.org> ---
I'm not sure this is a bug, but this was definitely by design (as the comment
indicates). I think this is allowed by the successive standards (which are, in
any case, very weakly worded).

The root of the problem is that we want to allow for SYSTEM_CLOCK to return
high-precision values for large integer kinds, and fall back to lower-precision
results that fit in fewer bytes for smaller integer kinds. Thus, one should
call SYSTEM_CLOCK once with all the necessary arguments, and not multiple times
with varying argument types.

The only other consistent option I can see would be to simply go for
high-resolution results in all cases, but that would mean that SYSTEM_CLOCK
with 32-bit integers would wrap around in less than an hour.

If you have another idea, please post a list of what you think should happen in
all various cases (all possible combinations of arguments have to be allowed).