projects / rustc.git / blame
| Commit | Line | Data |
|---|---|---|
| e74abb32 XL |
1 | autocfg |
| 2 | ======= | |
| 3 | ||
| 4 | [](https://crates.io/crates/autocfg) | |
| 5 | [](https://docs.rs/autocfg) | |
| 6 |  | |
| 7 | [](https://travis-ci.org/cuviper/autocfg) | |
| 8 | ||
| 9 | A Rust library for build scripts to automatically configure code based on | |
| 10 | compiler support. Code snippets are dynamically tested to see if the `rustc` | |
| 11 | will accept them, rather than hard-coding specific version support. | |
| 12 | ||
| 13 | ||
| 14 | ## Usage | |
| 15 | ||
| 16 | Add this to your `Cargo.toml`: | |
| 17 | ||
| 18 | ```toml | |
| 19 | [build-dependencies] | |
| ba9703b0 | 20 | autocfg = "1" |
| e74abb32 XL |
21 | ``` |
| 22 | ||
| 23 | Then use it in your `build.rs` script to detect compiler features. For | |
| 24 | example, to test for 128-bit integer support, it might look like: | |
| 25 | ||
| 26 | ```rust | |
| 27 | extern crate autocfg; | |
| 28 | ||
| 29 | fn main() { | |
| 30 | let ac = autocfg::new(); | |
| 31 | ac.emit_has_type("i128"); | |
| 32 | ||
| 33 | // (optional) We don't need to rerun for anything external. | |
| ba9703b0 | 34 | autocfg::rerun_path("build.rs"); |
| e74abb32 XL |
35 | } |
| 36 | ``` | |
| 37 | ||
| 38 | If the type test succeeds, this will write a `cargo:rustc-cfg=has_i128` line | |
| 39 | for Cargo, which translates to Rust arguments `--cfg has_i128`. Then in the | |
| 40 | rest of your Rust code, you can add `#[cfg(has_i128)]` conditions on code that | |
| 41 | should only be used when the compiler supports it. | |
| 42 | ||
| 43 | ||
| 44 | ## Release Notes | |
| 45 | ||
| ba9703b0 XL |
46 | - 1.0.0 (2020-01-08) |
| 47 | - 🎉 Release 1.0! 🎉 (no breaking changes) | |
| 48 | - Add `probe_expression` and `emit_expression_cfg` to test arbitrary expressions. | |
| 49 | - Add `probe_constant` and `emit_constant_cfg` to test arbitrary constant expressions. | |
| 50 | ||
| dfeec247 XL |
51 | - 0.1.7 (2019-10-20) |
| 52 | - Apply `RUSTFLAGS` when probing `$TARGET != $HOST`, mainly for sysroot, by @roblabla. | |
| 53 | ||
| e74abb32 | 54 | - 0.1.6 (2019-08-19) |
| dfeec247 | 55 | - Add `probe`/`emit_sysroot_crate`, by @leo60228. |
| e74abb32 XL |
56 | |
| 57 | - 0.1.5 (2019-07-16) | |
| 58 | - Mask some warnings from newer rustc. | |
| 59 | ||
| 60 | - 0.1.4 (2019-05-22) | |
| 61 | - Relax `std`/`no_std` probing to a warning instead of an error. | |
| 62 | - Improve `rustc` bootstrap compatibility. | |
| 63 | ||
| 64 | - 0.1.3 (2019-05-21) | |
| dfeec247 | 65 | - Auto-detects if `#![no_std]` is needed for the `$TARGET`. |
| e74abb32 XL |
66 | |
| 67 | - 0.1.2 (2019-01-16) | |
| dfeec247 XL |
68 | - Add `rerun_env(ENV)` to print `cargo:rerun-if-env-changed=ENV`. |
| 69 | - Add `rerun_path(PATH)` to print `cargo:rerun-if-changed=PATH`. | |
| e74abb32 XL |
70 | |
| 71 | ||
| 72 | ## Minimum Rust version policy | |
| 73 | ||
| 74 | This crate's minimum supported `rustc` version is `1.0.0`. Compatibility is | |
| 75 | its entire reason for existence, so this crate will be extremely conservative | |
| 76 | about raising this requirement. If this is ever deemed necessary, it will be | |
| 77 | treated as a major breaking change for semver purposes. | |
| 78 | ||
| 79 | ||
| 80 | ## License | |
| 81 | ||
| 82 | This project is licensed under either of | |
| 83 | ||
| 84 | * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or | |
| 85 | http://www.apache.org/licenses/LICENSE-2.0) | |
| 86 | * MIT license ([LICENSE-MIT](LICENSE-MIT) or | |
| 87 | http://opensource.org/licenses/MIT) | |
| 88 | ||
| 89 | at your option. |