Crate outer_attribute 

At the time of writing, syn crate doesn’t offer a way to parse outer attributes (for example, #[repr(c)]) without declaring a struct and reinventing a wheel by implementing syn::parse::Parse trait. Unlike syn::Attribute, depending on the enabled feature same_layout or different_layout the chosen different_layout::OuterAttribute or same_layout::OuterAttribute, respectively, will have syn::parse::Parse available.

Example

extern crate syn;
extern crate outer_attribute;

use outer_attribute::different_layout::OuterAttribute;

fn main() {
    assert!(matches!(syn::parse_str::<OuterAttribute>("#[repr(C)]"), Ok(_)));
    assert!(matches!(syn::parse_str::<OuterAttribute>("Not an outer attribute"), Err(_)));
}

The default feature is different_layout and opting for same_layout instead can be considered when there is some functionality that is available on syn::Attribute but not on either OuterAttribute.

Modules

different_layout

same_layout