Auto-generate lint documentation.

Author: ehuss

Cargo.lock

@@ -1677,6 +1677,15 @@ version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8dd5a6d5999d9907cda8ed67bbd137d3af8085216c2ac62de5be860bd41f304a"
 
+[[package]]
+name = "lint-docs"
+version = "0.1.0"
+dependencies = [
+ "serde_json",
+ "tempfile",
+ "walkdir",
+]
+
 [[package]]
 name = "lock_api"
 version = "0.3.4"

Cargo.toml

@@ -9,6 +9,7 @@ members = [
   "src/tools/compiletest",
   "src/tools/error_index_generator",
   "src/tools/linkchecker",
+  "src/tools/lint-docs",
   "src/tools/rustbook",
   "src/tools/unstable-book-gen",
   "src/tools/tidy",

compiler/rustc_lint/src/array_into_iter.rs

@@ -7,6 +7,31 @@ use rustc_session::lint::FutureIncompatibleInfo;
 use rustc_span::symbol::sym;
 
 declare_lint! {
+    /// The `array_into_iter` lint detects calling `into_iter` on arrays.
+    ///
+    /// ### Example
+    ///
+    /// ```rust
+    /// # #![allow(unused)]
+    /// [1, 2, 3].into_iter().for_each(|n| { *n; });
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// In the future, it is planned to add an `IntoIter` implementation for
+    /// arrays such that it will iterate over *values* of the array instead of
+    /// references. Due to how method resolution works, this will change
+    /// existing code that uses `into_iter` on arrays. The solution to avoid
+    /// this warning is to use `iter()` instead of `into_iter()`.
+    ///
+    /// This is a [future-incompatible] lint to transition this to a hard error
+    /// in the future. See [issue #66145] for more details and a more thorough
+    /// description of the lint.
+    ///
+    /// [issue #66145]: https://github.com/rust-lang/rust/issues/66145
+    /// [future-incompatible]: ../index.md#future-incompatible-lints
     pub ARRAY_INTO_ITER,
     Warn,
     "detects calling `into_iter` on arrays",