Syntax warning: "is" used with literal. Did you mean "==" in compiler.py:271

[wjsuijlenh]

Python 3.10.6 (default on Ubuntu 22.04) gives a syntax warning about the suspicious use of "is" instead of "==" in the condition on line 271 of compiler.py:

 if Compilation.filename is "" and options.output is not None:

When I read the line, I also assume Compilation.filname == "" is meant instead.

 if Compilation.filename == "" and options.output is not None:

[xcsp3team]

Thanks for the issue. The modification has been performed and pushed