81 lines
2.6 KiB
Markdown
81 lines
2.6 KiB
Markdown
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# version\_check
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[](https://github.com/SergioBenitez/version_check/actions)
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[](https://crates.io/crates/version_check)
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[](https://docs.rs/version_check)
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This tiny crate checks that the running or installed `rustc` meets some version
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requirements. The version is queried by calling the Rust compiler with
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`--version`. The path to the compiler is determined first via the `RUSTC`
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environment variable. If it is not set, then `rustc` is used. If that fails, no
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determination is made, and calls return `None`.
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## Usage
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Add to your `Cargo.toml` file, typically as a build dependency:
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```toml
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[build-dependencies]
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version_check = "0.9"
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```
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`version_check` is compatible and compiles with Rust 1.0.0 and beyond.
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## Examples
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Set a `cfg` flag in `build.rs` if the running compiler was determined to be
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at least version `1.13.0`:
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```rust
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extern crate version_check as rustc;
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if rustc::is_min_version("1.13.0").unwrap_or(false) {
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println!("cargo:rustc-cfg=question_mark_operator");
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}
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```
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Check that the running compiler was released on or after `2018-12-18`:
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```rust
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extern crate version_check as rustc;
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match rustc::is_min_date("2018-12-18") {
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Some(true) => "Yep! It's recent!",
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Some(false) => "No, it's older.",
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None => "Couldn't determine the rustc version."
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};
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```
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Check that the running compiler supports feature flags:
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```rust
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extern crate version_check as rustc;
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match rustc::is_feature_flaggable() {
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Some(true) => "Yes! It's a dev or nightly release!",
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Some(false) => "No, it's stable or beta.",
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None => "Couldn't determine the rustc version."
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};
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```
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See the [rustdocs](https://docs.rs/version_check) for more examples and complete
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documentation.
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## Alternatives
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This crate is dead simple with no dependencies. If you need something more and
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don't care about panicking if the version cannot be obtained, or if you don't
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mind adding dependencies, see [rustc_version]. If you'd instead prefer a feature
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detection library that works by dynamically invoking `rustc` with a
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representative code sample, see [autocfg].
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[rustc_version]: https://crates.io/crates/rustc_version
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[autocfg]: https://crates.io/crates/autocfg
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## License
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`version_check` is licensed under either of the following, at your option:
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* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
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* MIT License ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)
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