macros: Error out on unknown/invalid attributes

[sdroege]

E.g. the following should fail

#[derive(Debug, Copy, Clone, PartialEq, Eq, glib::Enum)]
#[enum_type(name = "MyEnum", nullable)]

Only name is valid in that context.

[jf2048]

I just released a new crate deluxe that should make this a lot easier. I'd like to port the macros over to that, if it looks good?

[sdroege]

Sounds good to me, you want to send a PR?

[zecakeh]

Isn't this fixed? With the example above, nullable is flagged with an error message. It seems that #1096 made it mandatory to have attribute validation.