qualifier_attr

Procedural macro attributes for adding "qualifiers" to various items.

At the moment, the crate supports only functions with the following "qualifiers":

• pub, pub(crate), ... - visibility qualifiers
• async - async qualifier
• unsafe - unsafe qualifier
• const - const qualifier
• extern "ABI" - ABI qualifier

as well as structures with pub, pub(crate), etc visibility qualifiers.

Modules can't be supported due to hygiene issues.

Named fields within structs can't be supported because as far as the author understands, attribute macros can't be applied to them.

Examples

use qualifier_attr::fn_qualifiers;

// We can add a qualifier to a function
// with an attribute.
#[fn_qualifiers(const)]
fn const_fn() -> u32 { 42 }

const CONST_RES: u32 = const_fn();

// It's not so impresive on its own
// but with cfg_attr it can be conditional.

#[cfg_attr(feature = "extern_c", no_mangle, fn_qualifiers(pub, extern "C"))]
fn extern_c_fn() -> u32 { 42 }

Learn more about cfg_attr here.

Similar crates

• const_fn.

License