--- /dev/null
+//! [![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;
+
+const RUSTVERSION: Version = include!(concat!(env!("OUT_DIR"), "/version.rs"));
+
+#[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(RUSTVERSION) {
+ 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(RUSTVERSION) {
+ 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),
+ ))
+ }
+ }
+}
projects / rustc.git / blobdiff