qualifier_attr 0.1.6

Procedural macro attributes for adding "qualifiers" (pub, async, unsafe, extern "C",...) to various items.
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# qualifier_attr


[![Latest Version](https://img.shields.io/crates/v/qualifier_attr.svg)][`qualifier_attr`]
[![Downloads](https://img.shields.io/crates/d/qualifier_attr.svg)][`qualifier_attr`]
[![Documentation](https://docs.rs/qualifier_attr/badge.svg)][`qualifier_attr`/docs]
[![License](https://img.shields.io/crates/l/qualifier_attr.svg)][`qualifier_attr`/license]
[![Dependency Status](https://deps.rs/repo/github/JohnScience/qualifier_attr/status.svg)][`qualifier_attr`/dep_status]

> 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


```rust
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](https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute).

## Similar crates


* [`const_fn`](https://crates.io/crates/const_fn).

## License


<sup>
Licensed under either of <a href="LICENSE-APACHE">Apache License, Version
2.0</a> or <a href="LICENSE-MIT">MIT license</a> at your option.
</sup>

<br>

<sub>
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in this crate by you, as defined in the Apache-2.0 license, shall
be dual licensed as above, without any additional terms or conditions.
</sub>

[`qualifier_attr`]: https://crates.io/crates/qualifier_attr
[`qualifier_attr`/docs]: https://docs.rs/qualifier_attr
[`qualifier_attr`/license]: https://github.com/JohnScience/qualifier_attr#license
[`qualifier_attr`/dep_status]: https://deps.rs/repo/github/JohnScience/qualifier_attr