Missing option '-f/--free-search' in flags of command line help

[raphaelboudreault]

OS: Linux Ubuntu 22.04
MZN version: 2.8.5

Using minizinc --help <solver> from the command line (for example with Chuffed), option -f/``--free-search" is not described in the output. Shouldn't it be part of the "MZN-FZN plugin options"?

[CervEdin]

I think the solvers are responsible for providing the solver help text.

What --free-search does is not set in stone and I think that all it means is what is described here:
https://docs.minizinc.dev/en/stable/command_line.html#cmdoption-f

Instructs the solver to conduct a “free search”, i.e., ignore any search annotations. The solver is not required to ignore the annotations, but it is allowed to do so.

In OR-Tools

My understanding is that in OR-Tools you can use -f to use it's portfolio solving when only using 1 thread.
AFAIK this is not thoroughly described anywhere but it can be deduced by diving into the source code here:
https://github.com/google/or-tools/blob/ed94162b910fa58896db99191378d3b71a5313af/ortools/flatzinc/cp_model_fz_solver.cc#L1399C1-L1400C72

My understanding of OR-Tools does here is that it will use search annotations for one worker (CP-SAT) but still use other workers like the LNS and local-search workers which will not care about search annotations.

It should be noted that for this solver, my understand is that you are better off using parallel workers, either using --parallel or the num_workers SAT parameter instead of --free-search.

Also note that -f will not be used if you specify workers >1 or if solving for satisfiability.