fix: allow the dispatch macro to work with no args

[sashetophizika]

Currently the dispatch! macro does not work with dispatchers that do not have any additional parameters. This PR fixes it.

I am getting some incorrect argument diagnostics from rust_analyzer, but everything compiles and clippy does not mind so I don't know.

[sashetophizika]

Sorry, it turns out that this is a nightmare.

Are you willing to accept an implementation that separates the macro in two (one that specifies the instance and one that doesn't)? I can fix the examples that break if you do. If not, just close.

[yavko]

Sorry, it turns out that this is a nightmare.

Are you willing to accept an implementation that separates the macro in two (one that specifies the instance and one that doesn't)? I can fix the examples that break if you do. If not, just close.

Sure

[sashetophizika]

Alternatively this implementation that i just pushed changes the separator for the instance argument to ; and matches properly for all use cases. This way we can keep it one macro.

[yavko]

Alternatively this implementation that i just pushed changes the separator for the instance argument to ; and matches properly for all use cases. This way we can keep it one macro.

Great

[sashetophizika]

If you like it then I think it can be merged.

[yavko]

I like this