What problem does this solve or what need does it fill?

The current error messages for when system parameters is wrong is very opaque. As an example:

 no method named `system` found for fn item `for<'r, 's, 't0, 't1> fn(Query<'r, (bevy::prelude::Entity, &'s AttackBonus, &'t0 Defense, &'t1 Advantage), bevy::prelude::With<(Active, Attack)>>, Commands) {check_attacks}` in the current scope
`check_attacks` is a function, perhaps you wish to call it

This is particularly painful because these mistakes are a common beginner issue and there's no clear path forward.

What solution would you like?

The compiler examines each of your system's parameters, explains which one fails, and ideally makes a simple suggestion on how to correct it.

What alternative(s) have you considered?

None.

Additional context

The relevant macros would be cleaned up substantially if variadic generics ever lands.