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 style="display:inline">#[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 style="display:inline">#[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 style="display:inline">#[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 style="display:inline">#[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 style="display:inline">#[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 style="display:inline">#[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 style="display:inline">#[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 style="display:inline">#[rustversion::before(</code></b><i>version or date</i><b><code style="display:inline">)]</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 style="display:inline">#[rustversion::not(</code></b><i>selector</i><b><code style="display:inline">)]</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 style="display:inline">#[rustversion::any(</code></b><i>selectors...</i><b><code style="display:inline">)]</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 style="display:inline">#[rustversion::all(</code></b><i>selectors...</i><b><code style="display:inline">)]</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 style="display:inline">#[rustversion::attr(</code></b><i>selector</i><b><code style="display:inline">, </code></b><i>attribute</i><b><code style="display:inline">)]</code></b>
91//! —<br>
92//! For conditional inclusion of attributes; analogous to
93//! <code style="display:inline">cfg_attr</code>.
94//! </p>
95//!
96//! - <p style="margin-left:50px;text-indent:-50px">
97//! <b><code style="display:inline">rustversion::cfg!(</code></b><i>selector</i><b><code style="display:inline">)</code></b>
98//! —<br>
99//! An expression form of any of the above attributes; for example
100//! <i>if rustversion::cfg!(any(stable, beta)) { ... }</i>.
101//! </p>
102//!
103//! <br>
104//!
105//! # Use cases
106//!
107//! Providing additional trait impls as types are stabilized in the standard library
108//! without breaking compatibility with older compilers; in this case Pin\<P\>
109//! stabilized in [Rust 1.33][pin]:
110//!
111//! [pin]: https://blog.rust-lang.org/2019/02/28/Rust-1.33.0.html#pinning
112//!
113//! ```
114//! # trait MyTrait {}
115//! #
116//! #[rustversion::since(1.33)]
117//! use std::pin::Pin;
118//!
119//! #[rustversion::since(1.33)]
120//! impl<P: MyTrait> MyTrait for Pin<P> {
121//! /* ... */
122//! }
123//! ```
124//!
125//! Similar but for language features; the ability to control alignment greater than
126//! 1 of packed structs was stabilized in [Rust 1.33][packed].
127//!
128//! [packed]: https://github.com/rust-lang/rust/blob/master/RELEASES.md#version-1330-2019-02-28
129//!
130//! ```
131//! #[rustversion::attr(before(1.33), repr(packed))]
132//! #[rustversion::attr(since(1.33), repr(packed(2)))]
133//! struct Six(i16, i32);
134//!
135//! fn main() {
136//! println!("{}", std::mem::align_of::<Six>());
137//! }
138//! ```
139//!
140//! Augmenting code with `const` as const impls are stabilized in the standard
141//! library. This use of `const` as an attribute is recognized as a special case
142//! by the rustversion::attr macro.
143//!
144//! ```
145//! use std::time::Duration;
146//!
147//! #[rustversion::attr(since(1.32), const)]
148//! fn duration_as_days(dur: Duration) -> u64 {
149//! dur.as_secs() / 60 / 60 / 24
150//! }
151//! ```
152//!
153//! Emitting Cargo cfg directives from a build script. Note that this requires
154//! listing `rustversion` under `[build-dependencies]` in Cargo.toml, not
155//! `[dependencies]`.
156//!
157//! ```
158//! // build.rs
159//!
160//! fn main() {
161//! if rustversion::cfg!(since(1.36)) {
162//! println!("cargo:rustc-cfg=no_std");
163//! }
164//! }
165//! ```
166//!
167//! ```
168//! // src/lib.rs
169//!
170//! #![cfg_attr(no_std, no_std)]
171//!
172//! #[cfg(no_std)]
173//! extern crate alloc;
174//! ```
175//!
176//! <br>
177
178#![doc(html_root_url = "https://docs.rs/rustversion/1.0.19")]
179#![allow(
180 clippy::cast_lossless,
181 clippy::cast_possible_truncation,
182 clippy::derive_partial_eq_without_eq,
183 clippy::doc_markdown,
184 clippy::enum_glob_use,
185 clippy::from_iter_instead_of_collect,
186 // https://github.com/rust-lang/rust-clippy/issues/8539
187 clippy::iter_with_drain,
188 clippy::module_name_repetitions,
189 clippy::must_use_candidate,
190 clippy::needless_doctest_main,
191 clippy::needless_pass_by_value,
192 clippy::redundant_else,
193 clippy::toplevel_ref_arg,
194 clippy::unreadable_literal
195)]
196
197extern crate proc_macro;
198
199mod attr;
200mod bound;
201mod constfn;
202mod date;
203mod error;
204mod expand;
205mod expr;
206mod iter;
207mod release;
208mod time;
209mod token;
210mod version;
211
212use crate::error::Error;
213use crate::version::Version;
214use proc_macro::TokenStream;
215
216#[cfg(not(host_os = "windows"))]
217const RUSTVERSION: Version = include!(concat!(env!("OUT_DIR"), "/version.expr"));
218
219#[cfg(host_os = "windows")]
220const RUSTVERSION: Version = include!(concat!(env!("OUT_DIR"), "\\version.expr"));
221
222#[proc_macro_attribute]
223pub fn stable(args: TokenStream, input: TokenStream) -> TokenStream {
224 expand::cfg(introducer:"stable", args, input)
225}
226
227#[proc_macro_attribute]
228pub fn beta(args: TokenStream, input: TokenStream) -> TokenStream {
229 expand::cfg(introducer:"beta", args, input)
230}
231
232#[proc_macro_attribute]
233pub fn nightly(args: TokenStream, input: TokenStream) -> TokenStream {
234 expand::cfg(introducer:"nightly", args, input)
235}
236
237#[proc_macro_attribute]
238pub fn since(args: TokenStream, input: TokenStream) -> TokenStream {
239 expand::cfg(introducer:"since", args, input)
240}
241
242#[proc_macro_attribute]
243pub fn before(args: TokenStream, input: TokenStream) -> TokenStream {
244 expand::cfg(introducer:"before", args, input)
245}
246
247#[proc_macro_attribute]
248pub fn not(args: TokenStream, input: TokenStream) -> TokenStream {
249 expand::cfg(introducer:"not", args, input)
250}
251
252#[proc_macro_attribute]
253pub fn any(args: TokenStream, input: TokenStream) -> TokenStream {
254 expand::cfg(introducer:"any", args, input)
255}
256
257#[proc_macro_attribute]
258pub fn all(args: TokenStream, input: TokenStream) -> TokenStream {
259 expand::cfg(introducer:"all", args, input)
260}
261
262#[proc_macro_attribute]
263pub fn attr(args: TokenStream, input: TokenStream) -> TokenStream {
264 attr::parse(args)
265 .and_then(|args| expand::try_attr(args, input))
266 .unwrap_or_else(op:Error::into_compile_error)
267}
268
269#[cfg(not(cfg_macro_not_allowed))]
270#[proc_macro]
271pub fn cfg(input: TokenStream) -> TokenStream {
272 use proc_macro::{Ident, Span, TokenTree};
273 (|| {
274 let ref mut args = iter::new(input);
275 let expr = expr::parse(args)?;
276 token::parse_end(args)?;
277 let boolean = expr.eval(RUSTVERSION);
278 let ident = Ident::new(&boolean.to_string(), Span::call_site());
279 Ok(TokenStream::from(TokenTree::Ident(ident)))
280 })()
281 .unwrap_or_else(op:Error::into_compile_error)
282}
283