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&logoColor=white&logo=data:image/svg+xml;base64,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
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 #![allow(
149 clippy::cast_lossless,
150 clippy::cast_possible_truncation,
151 clippy::doc_markdown,
152 clippy::enum_glob_use,
153 clippy::from_iter_instead_of_collect,
154 clippy::module_name_repetitions,
155 clippy::must_use_candidate,
156 clippy::needless_doctest_main,
157 clippy::needless_pass_by_value,
158 clippy::redundant_else,
159 clippy::toplevel_ref_arg,
160 clippy::unreadable_literal
161 )]
162
163 extern crate proc_macro;
164
165 mod attr;
166 mod bound;
167 mod constfn;
168 mod date;
169 mod error;
170 mod expr;
171 mod iter;
172 mod release;
173 mod time;
174 mod token;
175 mod version;
176
177 use crate::attr::Then;
178 use crate::error::{Error, Result};
179 use crate::version::Version;
180 use proc_macro::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream, TokenTree};
181 use std::iter::FromIterator;
182
183 // ANDROID: Soong is providing the version of rustc via an env variable.
184 const ANDROID_RUSTVERSION: Option<&str> = option_env!("ANDROID_RUST_VERSION");
rust_version() -> Version185 fn rust_version() -> Version {
186 let v: Vec<&str> = ANDROID_RUSTVERSION.unwrap().split('.').collect();
187 Version {
188 minor: v[1].parse().unwrap(),
189 patch: v[2].parse().unwrap(),
190 channel: version::Channel::Stable,
191 }
192 }
193
194 #[proc_macro_attribute]
stable(args: TokenStream, input: TokenStream) -> TokenStream195 pub fn stable(args: TokenStream, input: TokenStream) -> TokenStream {
196 cfg("stable", args, input)
197 }
198
199 #[proc_macro_attribute]
beta(args: TokenStream, input: TokenStream) -> TokenStream200 pub fn beta(args: TokenStream, input: TokenStream) -> TokenStream {
201 cfg("beta", args, input)
202 }
203
204 #[proc_macro_attribute]
nightly(args: TokenStream, input: TokenStream) -> TokenStream205 pub fn nightly(args: TokenStream, input: TokenStream) -> TokenStream {
206 cfg("nightly", args, input)
207 }
208
209 #[proc_macro_attribute]
since(args: TokenStream, input: TokenStream) -> TokenStream210 pub fn since(args: TokenStream, input: TokenStream) -> TokenStream {
211 cfg("since", args, input)
212 }
213
214 #[proc_macro_attribute]
before(args: TokenStream, input: TokenStream) -> TokenStream215 pub fn before(args: TokenStream, input: TokenStream) -> TokenStream {
216 cfg("before", args, input)
217 }
218
219 #[proc_macro_attribute]
not(args: TokenStream, input: TokenStream) -> TokenStream220 pub fn not(args: TokenStream, input: TokenStream) -> TokenStream {
221 cfg("not", args, input)
222 }
223
224 #[proc_macro_attribute]
any(args: TokenStream, input: TokenStream) -> TokenStream225 pub fn any(args: TokenStream, input: TokenStream) -> TokenStream {
226 cfg("any", args, input)
227 }
228
229 #[proc_macro_attribute]
all(args: TokenStream, input: TokenStream) -> TokenStream230 pub fn all(args: TokenStream, input: TokenStream) -> TokenStream {
231 cfg("all", args, input)
232 }
233
cfg(introducer: &str, args: TokenStream, input: TokenStream) -> TokenStream234 fn cfg(introducer: &str, args: TokenStream, input: TokenStream) -> TokenStream {
235 try_cfg(introducer, args, input).unwrap_or_else(Error::into_compile_error)
236 }
237
try_cfg(introducer: &str, args: TokenStream, input: TokenStream) -> Result<TokenStream>238 fn try_cfg(introducer: &str, args: TokenStream, input: TokenStream) -> Result<TokenStream> {
239 let introducer = Ident::new(introducer, Span::call_site());
240
241 let mut full_args = TokenStream::from(TokenTree::Ident(introducer));
242 if !args.is_empty() {
243 full_args.extend(std::iter::once(TokenTree::Group(Group::new(
244 Delimiter::Parenthesis,
245 args,
246 ))));
247 }
248
249 let ref mut full_args = iter::new(full_args);
250 let expr = expr::parse(full_args)?;
251 token::parse_end(full_args)?;
252
253 if expr.eval(rust_version()) {
254 Ok(input)
255 } else {
256 Ok(TokenStream::new())
257 }
258 }
259
260 #[proc_macro_attribute]
attr(args: TokenStream, input: TokenStream) -> TokenStream261 pub fn attr(args: TokenStream, input: TokenStream) -> TokenStream {
262 attr::parse(args)
263 .and_then(|args| try_attr(args, input))
264 .unwrap_or_else(Error::into_compile_error)
265 }
266
try_attr(args: attr::Args, input: TokenStream) -> Result<TokenStream>267 fn try_attr(args: attr::Args, input: TokenStream) -> Result<TokenStream> {
268 if !args.condition.eval(rust_version()) {
269 return Ok(input);
270 }
271
272 match args.then {
273 Then::Const(const_token) => constfn::insert_const(input, const_token),
274 Then::Attribute(then) => {
275 // #[cfg_attr(all(), #then)]
276 Ok(TokenStream::from_iter(
277 vec![
278 TokenTree::Punct(Punct::new('#', Spacing::Alone)),
279 TokenTree::Group(Group::new(
280 Delimiter::Bracket,
281 TokenStream::from_iter(vec![
282 TokenTree::Ident(Ident::new("cfg_attr", Span::call_site())),
283 TokenTree::Group(Group::new(
284 Delimiter::Parenthesis,
285 TokenStream::from_iter(
286 vec![
287 TokenTree::Ident(Ident::new("all", Span::call_site())),
288 TokenTree::Group(Group::new(
289 Delimiter::Parenthesis,
290 TokenStream::new(),
291 )),
292 TokenTree::Punct(Punct::new(',', Spacing::Alone)),
293 ]
294 .into_iter()
295 .chain(then),
296 ),
297 )),
298 ]),
299 )),
300 ]
301 .into_iter()
302 .chain(input),
303 ))
304 }
305 }
306 }
307