Attributes Structure

[philberty]

I wonder is it worth checking in Rustc to see if their Attributes structure cleans this up for you in the parser so you get a structure like:

string attr_name
bool has_rhs
string get_rhs

Originally posted by @philberty in #664 (comment)

[CohenArthur]

I think this part should live in its own header + source files. We can then add attribute-specific functions such as the one to handle #[path] as written by @mathstuf in #785

[mathstuf]

I'll note that it seems that rustc validates built-in attributes even if they aren't used. For example:

#[path = "foo"]
mod blah {
    #![path] // `rustc` errors even though it doesn't matter (the outer one "wins")
}