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diff --git a/rustversion/README.md b/rustversion/README.md deleted file mode 100644 index f7fdab1..0000000 --- a/rustversion/README.md +++ /dev/null @@ -1,138 +0,0 @@ -Compiler version cfg -==================== - -[](https://travis-ci.com/dtolnay/rustversion) -[](https://crates.io/crates/rustversion) -[](https://docs.rs/rustversion) - -This crate provides macros for conditional compilation according to rustc -compiler version, analogous to [`#[cfg(...)]`][cfg] and -[`#[cfg_attr(...)]`][cfg_attr]. - -[cfg]: https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg-attribute -[cfg_attr]: https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute - -```toml -[dependencies] -rustversion = "1.0" -``` - -<br> - -## Selectors - -- <b>`#[rustversion::stable]`</b> - —<br> - True on any stable compiler. - -- <b>`#[rustversion::stable(1.34)]`</b> - —<br> - True on exactly the specified stable compiler. - -- <b>`#[rustversion::beta]`</b> - —<br> - True on any beta compiler. - -- <b>`#[rustversion::nightly]`</b> - —<br> - True on any nightly compiler or dev build. - -- <b>`#[rustversion::nightly(2019-01-01)]`</b> - —<br> - True on exactly one nightly. - -- <b>`#[rustversion::since(1.34)]`</b> - —<br> - True on that stable release and any later compiler, including beta and - nightly. - -- <b>`#[rustversion::since(2019-01-01)]`</b> - —<br> - True on that nightly and all newer ones. - -- <b>`#[rustversion::before(`</b><i>version or date</i><b>`)]`</b> - —<br> - Negative of *#[rustversion::since(...)]*. - -- <b>`#[rustversion::not(`</b><i>selector</i><b>`)]`</b> - —<br> - Negative of any selector; for example *#[rustversion::not(nightly)]*. - -- <b>`#[rustversion::any(`</b><i>selectors...</i><b>`)]`</b> - —<br> - True if any of the comma-separated selectors is true; for example - *#[rustversion::any(stable, beta)]*. - -- <b>`#[rustversion::all(`</b><i>selectors...</i><b>`)]`</b> - —<br> - True if all of the comma-separated selectors are true; for example - *#[rustversion::all(since(1.31), before(1.34))]*. - -- <b>`#[rustversion::attr(`</b><i>selector</i><b>`, `</b><i>attribute</i><b>`)]`</b> - —<br> - For conditional inclusion of attributes; analogous to `cfg_attr`. - -<br> - -## Use cases - -Providing additional trait impls as types are stabilized in the standard library -without breaking compatibility with older compilers; in this case Pin\<P\> -stabilized in [Rust 1.33][pin]: - -[pin]: https://blog.rust-lang.org/2019/02/28/Rust-1.33.0.html#pinning - -```rust -#[rustversion::since(1.33)] -use std::pin::Pin; - -#[rustversion::since(1.33)] -impl<P: MyTrait> MyTrait for Pin<P> { - /* ... */ -} -``` - -Similar but for language features; the ability to control alignment greater than -1 of packed structs was stabilized in [Rust 1.33][packed]. - -[packed]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1330-2019-02-28 - -```rust -#[rustversion::attr(before(1.33), repr(packed))] -#[rustversion::attr(since(1.33), repr(packed(2)))] -struct Six(i16, i32); - -fn main() { - println!("{}", std::mem::align_of::<Six>()); -} -``` - -Augmenting code with `const` as const impls are stabilized in the standard -library. This use of `const` as an attribute is recognized as a special case by -the rustversion::attr macro. - -```rust -use std::time::Duration; - -#[rustversion::attr(since(1.32), const)] -fn duration_as_days(dur: Duration) -> u64 { - dur.as_secs() / 60 / 60 / 24 -} -``` - -<br> - -#### 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> |