Minizinc does not handle empty arguments well

[vdijken]

When I define my own separators everything is fine, but when I define an empty argument it seems to be skipped. In the past it worked fine. previous scripts which worked fine, now give different results. See the next example.
`$minizinc -a -n 2 2.mzn --soln-sep "%%%%%%%%%%%%%%%%%%%%%%%%%%%" --search-complete-msg "&&&&&&&&&&&&&&&&&&&&"
3 = 1 + 2
%%%%%%%%%%%%%%%%%%%%%%%%%%%
4 = 1 + 3
%%%%%%%%%%%%%%%%%%%%%%%%%%%

$ minizinc -a -n 2 2.mzn --soln-sep "" --search-complete-msg ""
3 = 1 + 2
--search-complete-msg
4 = 1 + 3
--search-complete-msg`

[cyderize]

Are you using Windows? I think this is actually this bug in PowerShell PowerShell/PowerShell#6280.

The workaround (over than upgrading to PowerShell 7.3 or using any other OS) is to run with --soln-sep `"`" --search-complete-msg `"`" or revert to using old Windows batch CMD.

I'm going to close this now as I don't think this is a bug in MiniZinc, but if you're running into this on a different operating system, please reopen this issue.

[vdijken]

I use Linux Mint latest version. I cannot find any issue on internet with the command line in a the terminal. I also installed Xterm and tried it there. Results are the same. I tried a shell command file and $# (number of arguments) shows then "" is seen as an argument.

[cyderize]

I haven't been able to reproduce this problem on Ubuntu 24.04 (which I think should behave the same as Linux Mint).

Which method did you use to install MiniZinc?

[vdijken]

Put distribution in some directory, Define alias for minizinc and minizincIDE.

[cyderize]

Is the issue still present when you directly call the minizinc binary without the alias? (You might have to use --solver chuffed if the Qt libs for Gecode aren't in your LD_LIBRARY_PATH)

[CervEdin]

Put distribution in some directory, Define alias for minizinc and minizincIDE.

How did you define the alias? Did you put --soln-sep "" in it?

[CervEdin]

I can repro if I incorrectly set the alias like this alias minizinc="minizinc -a --soln-sep "" --search-complete-msg """
You can fix it by using single quotes when declaring the alias alias minizinc='minizinc -a --soln-sep "" --search-complete-msg ""'

If this is the case, the cause of the issue is how the shell handles quotes, not minizinc

[CervEdin]

I would probably advice against setting an alias like this, unless you have a very, very good reason for it

[vdijken]

When not using an alias then I get this error, only for the solver cp-sat.
minizinc --solver cp-sat 3.mzn
...t/MiniZinc/bin/fzn-cp-sat: error while loading shared libraries: libabsl_flags_parse.so.2407.0.0: cannot open shared object file: No such file or directory
=====ERROR=====

[CervEdin]

This error due to a problem with the dynamic linking of the OR-Tools CP-SAT. CP-SAT uses an external dependency, abseil, and it needs to dynamically link the binary during runtime, but it fails to find in the usual places it's looking for it.

I'm not sure how aliasing the command solves this, you didn't share how you alias.
In general, you should be able to run a command in the same way as when using an alias by just writing out the entire alias.
But the issue you're seeing has to do with dynamic linking not working appropriately.

You should be able to fix it by either modifying and exporting the LD_LIBRARY environment variable, or using ldconfig.
I'm by no means an expert in dynamic linking but hopefully it points you in the right direction

[vdijken]

The point is when I define LD_LIBRARY_PATH as described in the manual, nothing else works like mc or gedit.

[cyderize]

To test the initial problem with the empty arguments, could you run a solver that doesn't require any shared libraries (e.g. --solver chuffed)? Basically given that I can't reproduce this on my Ubuntu installation, it seems likely that whatever method you're using to alias the minizinc command and setup the library paths is what's dropping the blank arguments.

For me, this is what I tried:

wget https://github.com/MiniZinc/MiniZincIDE/releases/download/2.9.3/MiniZincIDE-2.9.3-bundle-linux-x86_64.tgz
tar -xvf MiniZincIDE-2.9.3-bundle-linux-x86_64.tgz
echo "var 1..3: x;" > test.mzn
./MiniZincIDE-2.9.3-bundle-linux-x86_64/bin/minizinc --solver chuffed -a --soln-sep "" --search-complete-msg "" test.mzn

And I got the expected result

x = 3;
x = 2;
x = 1;