Update MSRV contribution docs

This commit is contained in:
Cameron Steffen 2021-04-26 15:47:39 -05:00
parent 340b570ea0
commit 3a8e759d8a

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@ -390,17 +390,23 @@ pass.
## Specifying the lint's minimum supported Rust version (MSRV)
Projects supporting older versions of Rust would need to disable a lint if it
targets features present in later versions. Support for this can be added by
specifying an MSRV in your lint like so,
Sometimes a lint makes suggestions that require a certain version of Rust. For example, the `manual_strip` lint suggests
using `str::strip_prefix` and `str::strip_suffix` which is only available after Rust 1.45. In such cases, you need to
ensure that the MSRV configured for the project is >= the MSRV of the required Rust feature. If multiple features are
required, just use the one with a lower MSRV.
First, add an MSRV alias for the required feature in [`clippy_utils::msrvs`](/clippy_utils/src/msrvs.rs). This can be
accessed later as `msrvs::STR_STRIP_PREFIX`, for example.
```rust
const MANUAL_STRIP_MSRV: RustcVersion = RustcVersion::new(1, 45, 0);
msrv_aliases! {
..
1,45,0 { STR_STRIP_PREFIX }
}
```
The project's MSRV will also have to be an attribute in the lint so you'll have
to add a struct and constructor for your lint. The project's MSRV needs to be
passed when the lint is registered in `lib.rs`
In order to access the project-configured MSRV, you need to have an `msrv` field in the LintPass struct, and a
constructor to initialize the field. The `msrv` value is passed to the constructor in `clippy_lints/lib.rs`.
```rust
pub struct ManualStrip {
@ -415,11 +421,11 @@ impl ManualStrip {
}
```
The project's MSRV can then be matched against the lint's `msrv` in the LintPass
The project's MSRV can then be matched against the feature MSRV in the LintPass
using the `meets_msrv` utility function.
``` rust
if !meets_msrv(self.msrv.as_ref(), &MANUAL_STRIP_MSRV) {
if !meets_msrv(self.msrv.as_ref(), &msrvs::STR_STRIP_PREFIX) {
return;
}
```