From 3a8e759d8a6250b77c37fd43a13aab34b82bbfbb Mon Sep 17 00:00:00 2001
From: Cameron Steffen <cam.steffen94@gmail.com>
Date: Mon, 26 Apr 2021 15:47:39 -0500
Subject: [PATCH] Update MSRV contribution docs
---
doc/adding_lints.md | 24 +++++++++++++++---------
1 file changed, 15 insertions(+), 9 deletions(-)
diff --git a/doc/adding_lints.md b/doc/adding_lints.md
index 50f0d724016..d6cc6d0c2c7 100644
--- a/doc/adding_lints.md
+++ b/doc/adding_lints.md
@@ -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;
}
```