Replace #[plugin_registrar] with exporting __rustc_plugin_registrar

compiler/rustc_feature/src/active.rs

@@ -281,9 +281,6 @@ declare_features! (
     // feature-group-start: actual feature gates
     // -------------------------------------------------------------------------
 
-    /// Allows using `#[plugin_registrar]` on functions.
-    (active, plugin_registrar, "1.0.0", Some(29597), None),
-
     /// Allows using `#![plugin(myplugin)]`.
     (active, plugin, "1.0.0", Some(29597), None),
 

compiler/rustc_feature/src/builtin_attrs.rs

@@ -291,18 +291,6 @@ pub const BUILTIN_ATTRIBUTES: &[BuiltinAttribute] = &[
     ),
 
     // Plugins:
-    (
-        sym::plugin_registrar, Normal, template!(Word),
-        Gated(
-            Stability::Deprecated(
-                "https://github.com/rust-lang/rust/pull/64675",
-                Some("may be removed in a future compiler version"),
-            ),
-            sym::plugin_registrar,
-            "compiler plugins are deprecated",
-            cfg_fn!(plugin_registrar)
-        )
-    ),
     (
         sym::plugin, CrateLevel, template!(List: "name"),
         Gated(

compiler/rustc_feature/src/removed.rs

@@ -136,9 +136,12 @@ declare_features! (
     (removed, main, "1.53.0", Some(29634), None, None),
     (removed, pub_macro_rules, "1.53.0", Some(78855), None,
      Some("removed due to being incomplete, in particular it does not work across crates")),
-     /// Allows the definition of `const` functions with some advanced features.
+    /// Allows the definition of `const` functions with some advanced features.
     (removed, const_fn, "1.54.0", Some(57563), None,
      Some("split into finer-grained feature gates")),
+    /// Allows using `#[plugin_registrar]` on functions.
+    (removed, plugin_registrar, "1.54.0", Some(29597), None,
+     Some("a __rustc_plugin_registrar symbol must now be defined instead")),
 
     /// Allows `#[doc(include = "some-file")]`.
     (removed, external_doc, "1.54.0", Some(44732), None,