From c0a9f722c40b728eef492040332d4616c1393e4e Mon Sep 17 00:00:00 2001
From: León Orell Valerian Liehr <me@fmease.dev>
Date: Tue, 5 Dec 2023 08:56:30 +0100
Subject: Undeprecate and use lint `unstable_features`

---
 compiler/rustc_lint/src/builtin.rs | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

(limited to 'compiler/rustc_lint/src')

diff --git a/compiler/rustc_lint/src/builtin.rs b/compiler/rustc_lint/src/builtin.rs
index 045ff38c056..324a8896a07 100644
--- a/compiler/rustc_lint/src/builtin.rs
+++ b/compiler/rustc_lint/src/builtin.rs
@@ -1233,10 +1233,30 @@ impl<'tcx> LateLintPass<'tcx> for MutableTransmutes {
 }
 
 declare_lint! {
-    /// The `unstable_features` is deprecated and should no longer be used.
+    /// The `unstable_features` lint detects uses of `#![feature]`.
+    ///
+    /// ### Example
+    ///
+    /// ```rust,compile_fail
+    /// #![deny(unstable_features)]
+    /// #![feature(test)]
+    /// ```
+    ///
+    /// {{produces}}
+    ///
+    /// ### Explanation
+    ///
+    /// In larger nightly-based projects which
+    ///
+    /// * consist of a multitude of crates where a subset of crates has to compile on
+    ///   stable either unconditionally or depending on a `cfg` flag to for example
+    ///   allow stable users to depend on them,
+    /// * don't use nightly for experimental features but for, e.g., unstable options only,
+    ///
+    /// this lint may come in handy to enforce policies of these kinds.
     UNSTABLE_FEATURES,
     Allow,
-    "enabling unstable features (deprecated. do not use)"
+    "enabling unstable features"
 }
 
 declare_lint_pass!(
@@ -1246,11 +1266,11 @@ declare_lint_pass!(
 
 impl<'tcx> LateLintPass<'tcx> for UnstableFeatures {
     fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &ast::Attribute) {
-        if attr.has_name(sym::feature) {
-            if let Some(items) = attr.meta_item_list() {
-                for item in items {
-                    cx.emit_spanned_lint(UNSTABLE_FEATURES, item.span(), BuiltinUnstableFeatures);
-                }
+        if attr.has_name(sym::feature)
+            && let Some(items) = attr.meta_item_list()
+        {
+            for item in items {
+                cx.emit_spanned_lint(UNSTABLE_FEATURES, item.span(), BuiltinUnstableFeatures);
             }
         }
     }
-- 
cgit 1.4.1-3-g733a5