rustversion/lib.rs
1//! [![github]](https://github.com/dtolnay/rustversion) [![crates-io]](https://crates.io/crates/rustversion) [![docs-rs]](https://docs.rs/rustversion)
2//!
3//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
4//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
5//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs
6//!
7//! <br>
8//!
9//! This crate provides macros for conditional compilation according to rustc
10//! compiler version, analogous to [`#[cfg(...)]`][cfg] and
11//! [`#[cfg_attr(...)]`][cfg_attr].
12//!
13//! [cfg]: https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg-attribute
14//! [cfg_attr]: https://doc.rust-lang.org/reference/conditional-compilation.html#the-cfg_attr-attribute
15//!
16//! <br>
17//!
18//! # Selectors
19//!
20//! - <p style="margin-left:50px;text-indent:-50px">
21//! <b><code>#[rustversion::stable]</code></b>
22//! —<br>
23//! True on any stable compiler.
24//! </p>
25//!
26//! - <p style="margin-left:50px;text-indent:-50px">
27//! <b><code>#[rustversion::stable(1.34)]</code></b>
28//! —<br>
29//! True on exactly the specified stable compiler.
30//! </p>
31//!
32//! - <p style="margin-left:50px;text-indent:-50px">
33//! <b><code>#[rustversion::beta]</code></b>
34//! —<br>
35//! True on any beta compiler.
36//! </p>
37//!
38//! - <p style="margin-left:50px;text-indent:-50px">
39//! <b><code>#[rustversion::nightly]</code></b>
40//! —<br>
41//! True on any nightly compiler or dev build.
42//! </p>
43//!
44//! - <p style="margin-left:50px;text-indent:-50px">
45//! <b><code>#[rustversion::nightly(2019-01-01)]</code></b>
46//! —<br>
47//! True on exactly one nightly.
48//! </p>
49//!
50//! - <p style="margin-left:50px;text-indent:-50px">
51//! <b><code>#[rustversion::since(1.34)]</code></b>
52//! —<br>
53//! True on that stable release and any later compiler, including beta and
54//! nightly.
55//! </p>
56//!
57//! - <p style="margin-left:50px;text-indent:-50px">
58//! <b><code>#[rustversion::since(2019-01-01)]</code></b>
59//! —<br>
60//! True on that nightly and all newer ones.
61//! </p>
62//!
63//! - <p style="margin-left:50px;text-indent:-50px">
64//! <b><code>#[rustversion::before(</code></b><i>version or date</i><b><code>)]</code></b>
65//! —<br>
66//! Negative of <i>#[rustversion::since(...)]</i>.
67//! </p>
68//!
69//! - <p style="margin-left:50px;text-indent:-50px">
70//! <b><code>#[rustversion::not(</code></b><i>selector</i><b><code>)]</code></b>
71//! —<br>
72//! Negative of any selector; for example <i>#[rustversion::not(nightly)]</i>.
73//! </p>
74//!
75//! - <p style="margin-left:50px;text-indent:-50px">
76//! <b><code>#[rustversion::any(</code></b><i>selectors...</i><b><code>)]</code></b>
77//! —<br>
78//! True if any of the comma-separated selectors is true; for example
79//! <i>#[rustversion::any(stable, beta)]</i>.
80//! </p>
81//!
82//! - <p style="margin-left:50px;text-indent:-50px">
83//! <b><code>#[rustversion::all(</code></b><i>selectors...</i><b><code>)]</code></b>
84//! —<br>
85//! True if all of the comma-separated selectors are true; for example
86//! <i>#[rustversion::all(since(1.31), before(1.34))]</i>.
87//! </p>
88//!
89//! - <p style="margin-left:50px;text-indent:-50px">
90//! <b><code>#[rustversion::attr(</code></b><i>selector</i><b><code>, </code></b><i>attribute</i><b><code>)]</code></b>
91//! —<br>
92//! For conditional inclusion of attributes; analogous to
93//! <code>cfg_attr</code>.
94//! </p>
95//!
96//! <br>
97//!
98//! # Use cases
99//!
100//! Providing additional trait impls as types are stabilized in the standard library
101//! without breaking compatibility with older compilers; in this case Pin\<P\>
102//! stabilized in [Rust 1.33][pin]:
103//!
104//! [pin]: https://blog.rust-lang.org/2019/02/28/Rust-1.33.0.html#pinning
105//!
106//! ```
107//! # trait MyTrait {}
108//! #
109//! #[rustversion::since(1.33)]
110//! use std::pin::Pin;
111//!
112//! #[rustversion::since(1.33)]
113//! impl<P: MyTrait> MyTrait for Pin<P> {
114//! /* ... */
115//! }
116//! ```
117//!
118//! Similar but for language features; the ability to control alignment greater than
119//! 1 of packed structs was stabilized in [Rust 1.33][packed].
120//!
121//! [packed]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1330-2019-02-28
122//!
123//! ```
124//! #[rustversion::attr(before(1.33), repr(packed))]
125//! #[rustversion::attr(since(1.33), repr(packed(2)))]
126//! struct Six(i16, i32);
127//!
128//! fn main() {
129//! println!("{}", std::mem::align_of::<Six>());
130//! }
131//! ```
132//!
133//! Augmenting code with `const` as const impls are stabilized in the standard
134//! library. This use of `const` as an attribute is recognized as a special case
135//! by the rustversion::attr macro.
136//!
137//! ```
138//! use std::time::Duration;
139//!
140//! #[rustversion::attr(since(1.32), const)]
141//! fn duration_as_days(dur: Duration) -> u64 {
142//! dur.as_secs() / 60 / 60 / 24
143//! }
144//! ```
145//!
146//! <br>
147
148#![doc(html_root_url = "https://docs.rs/rustversion/1.0.18")]
149#![allow(
150 clippy::cast_lossless,
151 clippy::cast_possible_truncation,
152 clippy::derive_partial_eq_without_eq,
153 clippy::doc_markdown,
154 clippy::enum_glob_use,
155 clippy::from_iter_instead_of_collect,
156 // https://github.com/rust-lang/rust-clippy/issues/8539
157 clippy::iter_with_drain,
158 clippy::module_name_repetitions,
159 clippy::must_use_candidate,
160 clippy::needless_doctest_main,
161 clippy::needless_pass_by_value,
162 clippy::redundant_else,
163 clippy::toplevel_ref_arg,
164 clippy::unreadable_literal
165)]
166
167extern crate proc_macro;
168
169mod attr;
170mod bound;
171mod constfn;
172mod date;
173mod error;
174mod expand;
175mod expr;
176mod iter;
177mod release;
178mod time;
179mod token;
180mod version;
181
182use crate::error::Error;
183use crate::version::Version;
184use proc_macro::TokenStream;
185
186#[cfg(not(host_os = "windows"))]
187const RUSTVERSION: Version = include!(concat!(env!("OUT_DIR"), "/version.expr"));
188
189#[cfg(host_os = "windows")]
190const RUSTVERSION: Version = include!(concat!(env!("OUT_DIR"), "\\version.expr"));
191
192#[proc_macro_attribute]
193pub fn stable(args: TokenStream, input: TokenStream) -> TokenStream {
194 expand::cfg("stable", args, input)
195}
196
197#[proc_macro_attribute]
198pub fn beta(args: TokenStream, input: TokenStream) -> TokenStream {
199 expand::cfg("beta", args, input)
200}
201
202#[proc_macro_attribute]
203pub fn nightly(args: TokenStream, input: TokenStream) -> TokenStream {
204 expand::cfg("nightly", args, input)
205}
206
207#[proc_macro_attribute]
208pub fn since(args: TokenStream, input: TokenStream) -> TokenStream {
209 expand::cfg("since", args, input)
210}
211
212#[proc_macro_attribute]
213pub fn before(args: TokenStream, input: TokenStream) -> TokenStream {
214 expand::cfg("before", args, input)
215}
216
217#[proc_macro_attribute]
218pub fn not(args: TokenStream, input: TokenStream) -> TokenStream {
219 expand::cfg("not", args, input)
220}
221
222#[proc_macro_attribute]
223pub fn any(args: TokenStream, input: TokenStream) -> TokenStream {
224 expand::cfg("any", args, input)
225}
226
227#[proc_macro_attribute]
228pub fn all(args: TokenStream, input: TokenStream) -> TokenStream {
229 expand::cfg("all", args, input)
230}
231
232#[proc_macro_attribute]
233pub fn attr(args: TokenStream, input: TokenStream) -> TokenStream {
234 attr::parse(args)
235 .and_then(|args| expand::try_attr(args, input))
236 .unwrap_or_else(Error::into_compile_error)
237}
238
239#[cfg(not(cfg_macro_not_allowed))]
240#[proc_macro]
241pub fn cfg(input: TokenStream) -> TokenStream {
242 use proc_macro::{Ident, Span, TokenTree};
243 (|| {
244 let ref mut args = iter::new(input);
245 let expr = expr::parse(args)?;
246 token::parse_end(args)?;
247 let boolean = expr.eval(RUSTVERSION);
248 let ident = Ident::new(&boolean.to_string(), Span::call_site());
249 Ok(TokenStream::from(TokenTree::Ident(ident)))
250 })()
251 .unwrap_or_else(Error::into_compile_error)
252}