//! [![github]](https://github.com/dtolnay/rustversion) [![crates-io]](https://crates.io/crates/rustversion) [![docs-rs]](https://docs.rs/rustversion)
//!
//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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
//!
//! <br>
//!
//! 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
//!
//! <br>
//!
//! # Selectors
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::stable]</code></b>
//! —<br>
//! True on any stable compiler.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::stable(1.34)]</code></b>
//! —<br>
//! True on exactly the specified stable compiler.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::beta]</code></b>
//! —<br>
//! True on any beta compiler.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::nightly]</code></b>
//! —<br>
//! True on any nightly compiler or dev build.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::nightly(2019-01-01)]</code></b>
//! —<br>
//! True on exactly one nightly.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::since(1.34)]</code></b>
//! —<br>
//! True on that stable release and any later compiler, including beta and
//! nightly.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::since(2019-01-01)]</code></b>
//! —<br>
//! True on that nightly and all newer ones.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::before(</code></b><i>version or date</i><b><code>)]</code></b>
//! —<br>
//! Negative of <i>#[rustversion::since(...)]</i>.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::not(</code></b><i>selector</i><b><code>)]</code></b>
//! —<br>
//! Negative of any selector; for example <i>#[rustversion::not(nightly)]</i>.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::any(</code></b><i>selectors...</i><b><code>)]</code></b>
//! —<br>
//! True if any of the comma-separated selectors is true; for example
//! <i>#[rustversion::any(stable, beta)]</i>.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::all(</code></b><i>selectors...</i><b><code>)]</code></b>
//! —<br>
//! True if all of the comma-separated selectors are true; for example
//! <i>#[rustversion::all(since(1.31), before(1.34))]</i>.
//! </p>
//!
//! - <p style="margin-left:50px;text-indent:-50px">
//! <b><code>#[rustversion::attr(</code></b><i>selector</i><b><code>, </code></b><i>attribute</i><b><code>)]</code></b>
//! —<br>
//! For conditional inclusion of attributes; analogous to
//! <code>cfg_attr</code>.
//! </p>
//!
//! <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
//!
//! ```
//! # trait MyTrait {}
//! #
//! #[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
//!
//! ```
//! #[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.
//!
//! ```
//! use std::time::Duration;
//!
//! #[rustversion::attr(since(1.32), const)]
//! fn duration_as_days(dur: Duration) -> u64 {
//! dur.as_secs() / 60 / 60 / 24
//! }
//! ```
//!
//! <br>
extern crate proc_macro;
mod attr;
mod bound;
mod constfn;
mod date;
mod error;
mod expr;
mod iter;
mod release;
mod time;
mod token;
mod version;
use crate::attr::Then;
use crate::error::{Error, Result};
use crate::version::Version;
use proc_macro::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
use std::iter::FromIterator;
// ANDROID: Soong is providing the version of rustc via an env variable.
const ANDROID_RUSTVERSION: &str = env!("ANDROID_RUST_VERSION");
fn rust_version() -> Version {
let v: Vec<&str> = ANDROID_RUSTVERSION.split('.').collect();
Version {
minor: v[1].parse().unwrap(),
patch: v[2].parse().unwrap(),
channel: version::Channel::Stable,
}
}
#[proc_macro_attribute]
pub fn stable(args: TokenStream, input: TokenStream) -> TokenStream {
cfg("stable", args, input)
}
#[proc_macro_attribute]
pub fn beta(args: TokenStream, input: TokenStream) -> TokenStream {
cfg("beta", args, input)
}
#[proc_macro_attribute]
pub fn nightly(args: TokenStream, input: TokenStream) -> TokenStream {
cfg("nightly", args, input)
}
#[proc_macro_attribute]
pub fn since(args: TokenStream, input: TokenStream) -> TokenStream {
cfg("since", args, input)
}
#[proc_macro_attribute]
pub fn before(args: TokenStream, input: TokenStream) -> TokenStream {
cfg("before", args, input)
}
#[proc_macro_attribute]
pub fn not(args: TokenStream, input: TokenStream) -> TokenStream {
cfg("not", args, input)
}
#[proc_macro_attribute]
pub fn any(args: TokenStream, input: TokenStream) -> TokenStream {
cfg("any", args, input)
}
#[proc_macro_attribute]
pub fn all(args: TokenStream, input: TokenStream) -> TokenStream {
cfg("all", args, input)
}
fn cfg(introducer: &str, args: TokenStream, input: TokenStream) -> TokenStream {
try_cfg(introducer, args, input).unwrap_or_else(Error::into_compile_error)
}
fn try_cfg(introducer: &str, args: TokenStream, input: TokenStream) -> Result<TokenStream> {
let introducer = Ident::new(introducer, Span::call_site());
let mut full_args = TokenStream::from(TokenTree::Ident(introducer));
if !args.is_empty() {
full_args.extend(std::iter::once(TokenTree::Group(Group::new(
Delimiter::Parenthesis,
args,
))));
}
let ref mut full_args = iter::new(full_args);
let expr = expr::parse(full_args)?;
token::parse_end(full_args)?;
if expr.eval(rust_version()) {
Ok(input)
} else {
Ok(TokenStream::new())
}
}
#[proc_macro_attribute]
pub fn attr(args: TokenStream, input: TokenStream) -> TokenStream {
attr::parse(args)
.and_then(|args| try_attr(args, input))
.unwrap_or_else(Error::into_compile_error)
}
fn try_attr(args: attr::Args, input: TokenStream) -> Result<TokenStream> {
if !args.condition.eval(rust_version()) {
return Ok(input);
}
match args.then {
Then::Const(const_token) => constfn::insert_const(input, const_token),
Then::Attribute(then) => {
// #[cfg_attr(all(), #then)]
Ok(TokenStream::from_iter(
vec![
TokenTree::Punct(Punct::new('#', Spacing::Alone)),
TokenTree::Group(Group::new(
Delimiter::Bracket,
TokenStream::from_iter(vec![
TokenTree::Ident(Ident::new("cfg_attr", Span::call_site())),
TokenTree::Group(Group::new(
Delimiter::Parenthesis,
TokenStream::from_iter(
vec![
TokenTree::Ident(Ident::new("all", Span::call_site())),
TokenTree::Group(Group::new(
Delimiter::Parenthesis,
TokenStream::new(),
)),
TokenTree::Punct(Punct::new(',', Spacing::Alone)),
]
.into_iter()
.chain(then),
),
)),
]),
)),
]
.into_iter()
.chain(input),
))
}
}
}