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diff --git a/third_party/rust/autocfg/README.md b/third_party/rust/autocfg/README.md new file mode 100644 index 0000000000..8c95696cd5 --- /dev/null +++ b/third_party/rust/autocfg/README.md @@ -0,0 +1,95 @@ +autocfg +======= + +[](https://crates.io/crates/autocfg) +[](https://docs.rs/autocfg) + + + +A Rust library for build scripts to automatically configure code based on +compiler support. Code snippets are dynamically tested to see if the `rustc` +will accept them, rather than hard-coding specific version support. + + +## Usage + +Add this to your `Cargo.toml`: + +```toml +[build-dependencies] +autocfg = "1" +``` + +Then use it in your `build.rs` script to detect compiler features. For +example, to test for 128-bit integer support, it might look like: + +```rust +extern crate autocfg; + +fn main() { + let ac = autocfg::new(); + ac.emit_has_type("i128"); + + // (optional) We don't need to rerun for anything external. + autocfg::rerun_path("build.rs"); +} +``` + +If the type test succeeds, this will write a `cargo:rustc-cfg=has_i128` line +for Cargo, which translates to Rust arguments `--cfg has_i128`. Then in the +rest of your Rust code, you can add `#[cfg(has_i128)]` conditions on code that +should only be used when the compiler supports it. + + +## Release Notes + +- 1.1.0 (2022-02-07) + - Use `CARGO_ENCODED_RUSTFLAGS` when it is set. + +- 1.0.1 (2020-08-20) + - Apply `RUSTFLAGS` for more `--target` scenarios, by @adamreichold. + +- 1.0.0 (2020-01-08) + - 🎉 Release 1.0! 🎉 (no breaking changes) + - Add `probe_expression` and `emit_expression_cfg` to test arbitrary expressions. + - Add `probe_constant` and `emit_constant_cfg` to test arbitrary constant expressions. + +- 0.1.7 (2019-10-20) + - Apply `RUSTFLAGS` when probing `$TARGET != $HOST`, mainly for sysroot, by @roblabla. + +- 0.1.6 (2019-08-19) + - Add `probe`/`emit_sysroot_crate`, by @leo60228. + +- 0.1.5 (2019-07-16) + - Mask some warnings from newer rustc. + +- 0.1.4 (2019-05-22) + - Relax `std`/`no_std` probing to a warning instead of an error. + - Improve `rustc` bootstrap compatibility. + +- 0.1.3 (2019-05-21) + - Auto-detects if `#![no_std]` is needed for the `$TARGET`. + +- 0.1.2 (2019-01-16) + - Add `rerun_env(ENV)` to print `cargo:rerun-if-env-changed=ENV`. + - Add `rerun_path(PATH)` to print `cargo:rerun-if-changed=PATH`. + + +## Minimum Rust version policy + +This crate's minimum supported `rustc` version is `1.0.0`. Compatibility is +its entire reason for existence, so this crate will be extremely conservative +about raising this requirement. If this is ever deemed necessary, it will be +treated as a major breaking change for semver purposes. + + +## License + +This project is licensed under either of + + * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or + http://www.apache.org/licenses/LICENSE-2.0) + * MIT license ([LICENSE-MIT](LICENSE-MIT) or + http://opensource.org/licenses/MIT) + +at your option. |