1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
//! [![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&logo=docs.rs
//!
//! <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>

#![doc(html_root_url = "https://docs.rs/rustversion/1.0.15")]
#![allow(
    clippy::cast_lossless,
    clippy::cast_possible_truncation,
    clippy::derive_partial_eq_without_eq,
    clippy::doc_markdown,
    clippy::enum_glob_use,
    clippy::from_iter_instead_of_collect,
    // https://github.com/rust-lang/rust-clippy/issues/8539
    clippy::iter_with_drain,
    clippy::module_name_repetitions,
    clippy::must_use_candidate,
    clippy::needless_doctest_main,
    clippy::needless_pass_by_value,
    clippy::redundant_else,
    clippy::toplevel_ref_arg,
    clippy::unreadable_literal
)]

extern crate proc_macro;

mod attr;
mod bound;
mod constfn;
mod date;
mod error;
mod expand;
mod expr;
mod iter;
mod release;
mod time;
mod token;
mod version;

use crate::error::Error;
use crate::version::Version;
use proc_macro::TokenStream;

const RUSTVERSION: Version = include!(concat!(env!("OUT_DIR"), "/version.expr"));

#[proc_macro_attribute]
pub fn stable(args: TokenStream, input: TokenStream) -> TokenStream {
    expand::cfg("stable", args, input)
}

#[proc_macro_attribute]
pub fn beta(args: TokenStream, input: TokenStream) -> TokenStream {
    expand::cfg("beta", args, input)
}

#[proc_macro_attribute]
pub fn nightly(args: TokenStream, input: TokenStream) -> TokenStream {
    expand::cfg("nightly", args, input)
}

#[proc_macro_attribute]
pub fn since(args: TokenStream, input: TokenStream) -> TokenStream {
    expand::cfg("since", args, input)
}

#[proc_macro_attribute]
pub fn before(args: TokenStream, input: TokenStream) -> TokenStream {
    expand::cfg("before", args, input)
}

#[proc_macro_attribute]
pub fn not(args: TokenStream, input: TokenStream) -> TokenStream {
    expand::cfg("not", args, input)
}

#[proc_macro_attribute]
pub fn any(args: TokenStream, input: TokenStream) -> TokenStream {
    expand::cfg("any", args, input)
}

#[proc_macro_attribute]
pub fn all(args: TokenStream, input: TokenStream) -> TokenStream {
    expand::cfg("all", args, input)
}

#[proc_macro_attribute]
pub fn attr(args: TokenStream, input: TokenStream) -> TokenStream {
    attr::parse(args)
        .and_then(|args| expand::try_attr(args, input))
        .unwrap_or_else(Error::into_compile_error)
}

#[cfg(not(cfg_macro_not_allowed))]
#[proc_macro]
pub fn cfg(input: TokenStream) -> TokenStream {
    use proc_macro::{Ident, Span, TokenTree};
    (|| {
        let ref mut args = iter::new(input);
        let expr = expr::parse(args)?;
        token::parse_end(args)?;
        let boolean = expr.eval(RUSTVERSION);
        let ident = Ident::new(&boolean.to_string(), Span::call_site());
        Ok(TokenStream::from(TokenTree::Ident(ident)))
    })()
    .unwrap_or_else(Error::into_compile_error)
}