Auto merge of #85296 - bjorn3:plugin_cleanup, r=petrochenkov

Plugin interface cleanup

The first commit performs two uncontroversial cleanups. The second commit removes `#[plugin_registrar]` and instead requires you to export a `__rustc_plugin_registrar` function, this will require a change to servo's script_plugins (cc `@jdm)`

compiler/rustc_ast_passes/src/feature_gate.rs

@@ -375,14 +375,6 @@ impl<'a> Visitor<'a> for PostExpansionVisitor<'a> {
             }
 
             ast::ItemKind::Fn(..) => {
-                if self.sess.contains_name(&i.attrs[..], sym::plugin_registrar) {
-                    gate_feature_post!(
-                        &self,
-                        plugin_registrar,
-                        i.span,
-                        "compiler plugins are experimental and possibly buggy"
-                    );
-                }
                 if self.sess.contains_name(&i.attrs[..], sym::start) {
                     gate_feature_post!(
                         &self,

compiler/rustc_codegen_ssa/src/back/symbol_export.rs

@@ -137,10 +137,6 @@ fn reachable_non_generics_provider(tcx: TyCtxt<'_>, cnum: CrateNum) -> DefIdMap<
         reachable_non_generics.insert(id.to_def_id(), SymbolExportLevel::C);
     }
 
-    if let Some(id) = tcx.plugin_registrar_fn(()) {
-        reachable_non_generics.insert(id.to_def_id(), SymbolExportLevel::C);
-    }
-
     reachable_non_generics
 }
 

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

@@ -139,6 +139,9 @@ declare_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,

compiler/rustc_interface/src/passes.rs

@@ -741,7 +741,6 @@ pub static DEFAULT_QUERY_PROVIDERS: SyncLazy<Providers> = SyncLazy::new(|| {
     let providers = &mut Providers::default();
     providers.analysis = analysis;
     proc_macro_decls::provide(providers);
-    plugin::build::provide(providers);
     rustc_middle::hir::provide(providers);
     mir::provide(providers);
     mir_build::provide(providers);
@@ -856,8 +855,6 @@ fn analysis(tcx: TyCtxt<'_>, (): ()) -> Result<()> {
             {
                 entry_point = sess.time("looking_for_entry_point", || tcx.entry_fn(()));
 
-                sess.time("looking_for_plugin_registrar", || tcx.ensure().plugin_registrar_fn(()));
-
                 sess.time("looking_for_derive_registrar", || {
                     tcx.ensure().proc_macro_decls_static(())
                 });

compiler/rustc_metadata/src/locator.rs

@@ -226,7 +226,7 @@ use rustc_session::config::{self, CrateType};
 use rustc_session::filesearch::{FileDoesntMatch, FileMatches, FileSearch};
 use rustc_session::search_paths::PathKind;
 use rustc_session::utils::CanonicalizedPath;
-use rustc_session::{Session, StableCrateId};
+use rustc_session::Session;
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
 use rustc_target::spec::{Target, TargetTriple};
@@ -787,7 +787,7 @@ pub fn find_plugin_registrar(
     metadata_loader: &dyn MetadataLoader,
     span: Span,
     name: Symbol,
-) -> (PathBuf, StableCrateId) {
+) -> PathBuf {
     match find_plugin_registrar_impl(sess, metadata_loader, name) {
         Ok(res) => res,
         // `core` is always available if we got as far as loading plugins.
@@ -799,7 +799,7 @@ fn find_plugin_registrar_impl<'a>(
     sess: &'a Session,
     metadata_loader: &dyn MetadataLoader,
     name: Symbol,
-) -> Result<(PathBuf, StableCrateId), CrateError> {
+) -> Result<PathBuf, CrateError> {
     info!("find plugin registrar `{}`", name);
     let mut locator = CrateLocator::new(
         sess,
@@ -816,7 +816,7 @@ fn find_plugin_registrar_impl<'a>(
 
     match locator.maybe_load_library_crate()? {
         Some(library) => match library.source.dylib {
-            Some(dylib) => Ok((dylib.0, library.metadata.get_root().stable_crate_id())),
+            Some(dylib) => Ok(dylib.0),
             None => Err(CrateError::NonDylibPlugin(name)),
         },
         None => Err(locator.into_error()),

compiler/rustc_middle/src/query/mod.rs

@@ -1252,9 +1252,6 @@ rustc_queries! {
     query entry_fn(_: ()) -> Option<(DefId, EntryFnType)> {
         desc { "looking up the entry function of a crate" }
     }
-    query plugin_registrar_fn(_: ()) -> Option<LocalDefId> {
-        desc { "looking up the plugin registrar for a crate" }
-    }
     query proc_macro_decls_static(_: ()) -> Option<LocalDefId> {
         desc { "looking up the derive registrar for a crate" }
     }

compiler/rustc_plugin_impl/src/build.rs

@@ -1,57 +0,0 @@
-//! Used by `rustc` when compiling a plugin crate.
-
-use rustc_hir as hir;
-use rustc_hir::def_id::LocalDefId;
-use rustc_hir::itemlikevisit::ItemLikeVisitor;
-use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::TyCtxt;
-use rustc_span::symbol::sym;
-use rustc_span::Span;
-
-struct RegistrarFinder<'tcx> {
-    tcx: TyCtxt<'tcx>,
-    registrars: Vec<(LocalDefId, Span)>,
-}
-
-impl<'v, 'tcx> ItemLikeVisitor<'v> for RegistrarFinder<'tcx> {
-    fn visit_item(&mut self, item: &hir::Item<'_>) {
-        if let hir::ItemKind::Fn(..) = item.kind {
-            let attrs = self.tcx.hir().attrs(item.hir_id());
-            if self.tcx.sess.contains_name(attrs, sym::plugin_registrar) {
-                self.registrars.push((item.def_id, item.span));
-            }
-        }
-    }
-
-    fn visit_trait_item(&mut self, _trait_item: &hir::TraitItem<'_>) {}
-
-    fn visit_impl_item(&mut self, _impl_item: &hir::ImplItem<'_>) {}
-
-    fn visit_foreign_item(&mut self, _foreign_item: &hir::ForeignItem<'_>) {}
-}
-
-/// Finds the function marked with `#[plugin_registrar]`, if any.
-fn plugin_registrar_fn(tcx: TyCtxt<'_>, (): ()) -> Option<LocalDefId> {
-    let mut finder = RegistrarFinder { tcx, registrars: Vec::new() };
-    tcx.hir().krate().visit_all_item_likes(&mut finder);
-
-    let (def_id, span) = finder.registrars.pop()?;
-
-    if !finder.registrars.is_empty() {
-        let diagnostic = tcx.sess.diagnostic();
-        let mut e = diagnostic.struct_err("multiple plugin registration functions found");
-        e.span_note(span, "one is here");
-        for &(_, span) in &finder.registrars {
-            e.span_note(span, "one is here");
-        }
-        e.emit();
-        diagnostic.abort_if_errors();
-        unreachable!();
-    }
-
-    Some(def_id)
-}
-
-pub fn provide(providers: &mut Providers) {
-    *providers = Providers { plugin_registrar_fn, ..*providers };
-}

compiler/rustc_plugin_impl/src/lib.rs

@@ -12,7 +12,6 @@
 
 use rustc_lint::LintStore;
 
-pub mod build;
 pub mod load;
 
 /// Structure used to register plugins.

compiler/rustc_plugin_impl/src/load.rs

@@ -55,20 +55,13 @@ fn load_plugin(
     metadata_loader: &dyn MetadataLoader,
     ident: Ident,
 ) {
-    let (lib, disambiguator) =
-        locator::find_plugin_registrar(sess, metadata_loader, ident.span, ident.name);
-    let symbol = sess.generate_plugin_registrar_symbol(disambiguator);
-    let fun = dylink_registrar(sess, ident.span, lib, symbol);
+    let lib = locator::find_plugin_registrar(sess, metadata_loader, ident.span, ident.name);
+    let fun = dylink_registrar(sess, ident.span, lib);
     plugins.push(fun);
 }
 
 // Dynamically link a registrar function into the compiler process.
-fn dylink_registrar(
-    sess: &Session,
-    span: Span,
-    path: PathBuf,
-    symbol: String,
-) -> PluginRegistrarFn {
+fn dylink_registrar(sess: &Session, span: Span, path: PathBuf) -> PluginRegistrarFn {
     use rustc_metadata::dynamic_lib::DynamicLibrary;
 
     // Make sure the path contains a / or the linker will search for it.
@@ -83,7 +76,7 @@ fn dylink_registrar(
     };
 
     unsafe {
-        let registrar = match lib.symbol(&symbol) {
+        let registrar = match lib.symbol("__rustc_plugin_registrar") {
             Ok(registrar) => mem::transmute::<*mut u8, PluginRegistrarFn>(registrar),
             // again fatal if we can't register macros
             Err(err) => sess.span_fatal(span, &err),
@@ -91,7 +84,7 @@ fn dylink_registrar(
 
         // Intentionally leak the dynamic library. We can't ever unload it
         // since the library can make things that will live arbitrarily long
-        // (e.g., an @-box cycle or a thread).
+        // (e.g., an Rc cycle or a thread).
         mem::forget(lib);
 
         registrar

compiler/rustc_session/src/session.rs

@@ -792,12 +792,6 @@ impl Session {
             )
     }
 
-    /// Returns the symbol name for the registrar function,
-    /// given the crate `Svh` and the function `DefIndex`.
-    pub fn generate_plugin_registrar_symbol(&self, stable_crate_id: StableCrateId) -> String {
-        format!("__rustc_plugin_registrar_{:08x}__", stable_crate_id.to_u64())
-    }
-
     pub fn generate_proc_macro_decls_symbol(&self, stable_crate_id: StableCrateId) -> String {
         format!("__rustc_proc_macro_decls_{:08x}__", stable_crate_id.to_u64())
     }

compiler/rustc_symbol_mangling/src/lib.rs

@@ -164,10 +164,6 @@ fn compute_symbol_name(
 
     // FIXME(eddyb) Precompute a custom symbol name based on attributes.
     let is_foreign = if let Some(def_id) = def_id.as_local() {
-        if tcx.plugin_registrar_fn(()) == Some(def_id) {
-            let stable_crate_id = tcx.sess.local_stable_crate_id();
-            return tcx.sess.generate_plugin_registrar_symbol(stable_crate_id);
-        }
         if tcx.proc_macro_decls_static(()) == Some(def_id) {
             let stable_crate_id = tcx.sess.local_stable_crate_id();
             return tcx.sess.generate_proc_macro_decls_symbol(stable_crate_id);

src/doc/unstable-book/src/language-features/plugin-registrar.md

@@ -1,13 +0,0 @@
-# `plugin_registrar`
-
-The tracking issue for this feature is: [#29597]
-
-[#29597]: https://github.com/rust-lang/rust/issues/29597
-
-This feature is part of "compiler plugins." It will often be used with the
-[`plugin`] and `rustc_private` features as well. For more details, see
-their docs.
-
-[`plugin`]: plugin.md
-
-------------------------

src/doc/unstable-book/src/language-features/plugin.md

@@ -6,9 +6,7 @@ The tracking issue for this feature is: [#29597]
 
 
 This feature is part of "compiler plugins." It will often be used with the
-[`plugin_registrar`] and `rustc_private` features.
-
-[`plugin_registrar`]: plugin-registrar.md
+`rustc_private` feature.
 
 ------------------------
 
@@ -39,7 +37,6 @@ additional checks for code style, safety, etc. Now let's write a plugin
 that warns about any item named `lintme`.
 
 ```rust,ignore (requires-stage-2)
-#![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 
 extern crate rustc_ast;
@@ -68,8 +65,8 @@ impl EarlyLintPass for Pass {
     }
 }
 
-#[plugin_registrar]
-pub fn plugin_registrar(reg: &mut Registry) {
+#[no_mangle]
+fn __rustc_plugin_registrar(reg: &mut Registry) {
     reg.lint_store.register_lints(&[&TEST_LINT]);
     reg.lint_store.register_early_pass(|| box Pass);
 }

src/test/ui-fulldeps/auxiliary/empty-plugin.rs

@@ -1,10 +1,9 @@
 // force-host
 
-#![feature(plugin_registrar)]
 #![feature(rustc_private)]
 
 extern crate rustc_driver;
 use rustc_driver::plugin::Registry;
 
-#[plugin_registrar]
-pub fn plugin_registrar(_: &mut Registry) {}
+#[no_mangle]
+fn __rustc_plugin_registrar(_: &mut Registry) {}

src/test/ui-fulldeps/auxiliary/issue-40001-plugin.rs

@@ -1,10 +1,9 @@
-#![feature(box_syntax, plugin, plugin_registrar, rustc_private)]
+#![feature(box_syntax, plugin, rustc_private)]
 #![crate_type = "dylib"]
 
 extern crate rustc_ast_pretty;
 extern crate rustc_driver;
 extern crate rustc_hir;
-#[macro_use]
 extern crate rustc_lint;
 #[macro_use]
 extern crate rustc_session;
@@ -16,11 +15,11 @@ use rustc_driver::plugin::Registry;
 use rustc_hir as hir;
 use rustc_hir::intravisit;
 use rustc_hir::Node;
-use rustc_lint::{LateContext, LateLintPass, LintArray, LintContext, LintPass};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_span::source_map;
 
-#[plugin_registrar]
-pub fn plugin_registrar(reg: &mut Registry) {
+#[no_mangle]
+fn __rustc_plugin_registrar(reg: &mut Registry) {
     reg.lint_store.register_lints(&[&MISSING_ALLOWED_ATTR]);
     reg.lint_store.register_late_pass(|| box MissingAllowedAttrPass);
 }

src/test/ui-fulldeps/auxiliary/lint-for-crate-rpass.rs

@@ -1,6 +1,6 @@
 // force-host
 
-#![feature(plugin_registrar, rustc_private)]
+#![feature(rustc_private)]
 #![feature(box_syntax)]
 
 extern crate rustc_driver;
@@ -64,8 +64,8 @@ fake_lint_pass! {
     Symbol::intern("crate_grey"), Symbol::intern("crate_green")
 }
 
-#[plugin_registrar]
-pub fn plugin_registrar(reg: &mut Registry) {
+#[no_mangle]
+fn __rustc_plugin_registrar(reg: &mut Registry) {
     reg.lint_store.register_lints(&[
         &CRATE_NOT_OKAY,
         &CRATE_NOT_RED,

src/test/ui-fulldeps/auxiliary/lint-for-crate.rs

@@ -1,6 +1,6 @@
 // force-host
 
-#![feature(plugin_registrar, rustc_private)]
+#![feature(rustc_private)]
 #![feature(box_syntax)]
 
 extern crate rustc_driver;
@@ -38,8 +38,8 @@ impl<'tcx> LateLintPass<'tcx> for Pass {
     }
 }
 
-#[plugin_registrar]
-pub fn plugin_registrar(reg: &mut Registry) {
+#[no_mangle]
+fn __rustc_plugin_registrar(reg: &mut Registry) {
     reg.lint_store.register_lints(&[&CRATE_NOT_OKAY]);
     reg.lint_store.register_late_pass(|| box Pass);
 }

src/test/ui-fulldeps/auxiliary/lint-group-plugin-test.rs

@@ -1,6 +1,5 @@
 // force-host
 
-#![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 
 // Load rustc as a plugin to get macros.
@@ -34,8 +33,8 @@ impl<'tcx> LateLintPass<'tcx> for Pass {
     }
 }
 
-#[plugin_registrar]
-pub fn plugin_registrar(reg: &mut Registry) {
+#[no_mangle]
+fn __rustc_plugin_registrar(reg: &mut Registry) {
     reg.lint_store.register_lints(&[&TEST_LINT, &PLEASE_LINT]);
     reg.lint_store.register_late_pass(|| box Pass);
     reg.lint_store.register_group(

src/test/ui-fulldeps/auxiliary/lint-plugin-test.rs

@@ -1,6 +1,5 @@
 // force-host
 
-#![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 
 extern crate rustc_ast;
@@ -29,8 +28,8 @@ impl EarlyLintPass for Pass {
     }
 }
 
-#[plugin_registrar]
-pub fn plugin_registrar(reg: &mut Registry) {
+#[no_mangle]
+fn __rustc_plugin_registrar(reg: &mut Registry) {
     reg.lint_store.register_lints(&[&TEST_LINT]);
     reg.lint_store.register_early_pass(|| box Pass);
 }

src/test/ui-fulldeps/auxiliary/lint-tool-test.rs

@@ -1,4 +1,3 @@
-#![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 
 extern crate rustc_ast;
@@ -44,8 +43,8 @@ impl EarlyLintPass for Pass {
     }
 }
 
-#[plugin_registrar]
-pub fn plugin_registrar(reg: &mut Registry) {
+#[no_mangle]
+fn __rustc_plugin_registrar(reg: &mut Registry) {
     reg.lint_store.register_lints(&[&TEST_RUSTC_TOOL_LINT, &TEST_LINT, &TEST_GROUP]);
     reg.lint_store.register_early_pass(|| box Pass);
     reg.lint_store.register_group(

src/test/ui-fulldeps/auxiliary/lto-syntax-extension-plugin.rs

@@ -1,6 +1,5 @@
 // force-host
 
-#![feature(plugin_registrar)]
 #![feature(rustc_private)]
 
 extern crate rustc_middle;
@@ -8,5 +7,5 @@ extern crate rustc_driver;
 
 use rustc_driver::plugin::Registry;
 
-#[plugin_registrar]
-pub fn plugin_registrar(_reg: &mut Registry) {}
+#[no_mangle]
+fn __rustc_plugin_registrar(_reg: &mut Registry) {}

src/test/ui-fulldeps/auxiliary/multiple-plugins-1.rs

@@ -0,0 +1,10 @@
+#![crate_type = "dylib"]
+#![feature(rustc_private)]
+
+extern crate rustc_middle;
+extern crate rustc_driver;
+
+use rustc_driver::plugin::Registry;
+
+#[no_mangle]
+fn __rustc_plugin_registrar(_: &mut Registry) {}

src/test/ui-fulldeps/auxiliary/multiple-plugins-2.rs

@@ -0,0 +1,10 @@
+#![crate_type = "dylib"]
+#![feature(rustc_private)]
+
+extern crate rustc_middle;
+extern crate rustc_driver;
+
+use rustc_driver::plugin::Registry;
+
+#[no_mangle]
+fn __rustc_plugin_registrar(_: &mut Registry) {}

src/test/ui-fulldeps/auxiliary/outlive-expansion-phase.rs

@@ -1,6 +1,5 @@
 // force-host
 
-#![feature(plugin_registrar)]
 #![feature(box_syntax, rustc_private)]
 
 extern crate rustc_middle;
@@ -18,8 +17,8 @@ impl Drop for Foo {
     fn drop(&mut self) {}
 }
 
-#[plugin_registrar]
-pub fn registrar(_: &mut Registry) {
+#[no_mangle]
+fn __rustc_plugin_registrar(_: &mut Registry) {
     thread_local!(static FOO: RefCell<Option<Box<Any+Send>>> = RefCell::new(None));
     FOO.with(|s| *s.borrow_mut() = Some(box Foo { foo: 10 } as Box<Any+Send>));
 }

src/test/ui-fulldeps/auxiliary/rlib-crate-test.rs

@@ -1,12 +1,12 @@
 // no-prefer-dynamic
 
 #![crate_type = "rlib"]
-#![feature(plugin_registrar, rustc_private)]
+#![feature(rustc_private)]
 
 extern crate rustc_middle;
 extern crate rustc_driver;
 
 use rustc_driver::plugin::Registry;
 
-#[plugin_registrar]
-pub fn plugin_registrar(_: &mut Registry) {}
+#[no_mangle]
+fn __rustc_plugin_registrar(_: &mut Registry) {}

src/test/ui-fulldeps/multiple-plugins.rs

@@ -0,0 +1,11 @@
+// run-pass
+// aux-build:multiple-plugins-1.rs
+// aux-build:multiple-plugins-2.rs
+
+// Check that the plugin registrar of multiple plugins doesn't conflict
+
+#![feature(plugin)]
+#![plugin(multiple_plugins_1)] //~ WARN use of deprecated attribute `plugin`
+#![plugin(multiple_plugins_2)] //~ WARN use of deprecated attribute `plugin`
+
+fn main() {}

src/test/ui-fulldeps/multiple-plugins.stderr

@@ -0,0 +1,16 @@
+warning: use of deprecated attribute `plugin`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
+  --> $DIR/multiple-plugins.rs:8:1
+   |
+LL | #![plugin(multiple_plugins_1)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: may be removed in a future compiler version
+   |
+   = note: `#[warn(deprecated)]` on by default
+
+warning: use of deprecated attribute `plugin`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
+  --> $DIR/multiple-plugins.rs:9:1
+   |
+LL | #![plugin(multiple_plugins_2)]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: may be removed in a future compiler version
+
+warning: 2 warnings emitted
+

src/test/ui/feature-gates/feature-gate-plugin_registrar.rs

@@ -1,11 +0,0 @@
-// Test that `#[plugin_registrar]` attribute is gated by `plugin_registrar`
-// feature gate.
-
-// the registration function isn't typechecked yet
-#[plugin_registrar]
-//~^ ERROR compiler plugins are deprecated
-//~| WARN use of deprecated attribute `plugin_registrar`: compiler plugins are deprecated
-pub fn registrar() {}
-//~^ ERROR compiler plugins are experimental and possibly buggy
-
-fn main() {}

src/test/ui/feature-gates/feature-gate-plugin_registrar.stderr

@@ -1,29 +0,0 @@
-error[E0658]: compiler plugins are experimental and possibly buggy
-  --> $DIR/feature-gate-plugin_registrar.rs:8:1
-   |
-LL | pub fn registrar() {}
-   | ^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #29597 <https://github.com/rust-lang/rust/issues/29597> for more information
-   = help: add `#![feature(plugin_registrar)]` to the crate attributes to enable
-
-error[E0658]: compiler plugins are deprecated
-  --> $DIR/feature-gate-plugin_registrar.rs:5:1
-   |
-LL | #[plugin_registrar]
-   | ^^^^^^^^^^^^^^^^^^^
-   |
-   = note: see issue #29597 <https://github.com/rust-lang/rust/issues/29597> for more information
-   = help: add `#![feature(plugin_registrar)]` to the crate attributes to enable
-
-warning: use of deprecated attribute `plugin_registrar`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
-  --> $DIR/feature-gate-plugin_registrar.rs:5:1
-   |
-LL | #[plugin_registrar]
-   | ^^^^^^^^^^^^^^^^^^^ help: may be removed in a future compiler version
-   |
-   = note: `#[warn(deprecated)]` on by default
-
-error: aborting due to 2 previous errors; 1 warning emitted
-
-For more information about this error, try `rustc --explain E0658`.

src/test/ui/feature-gates/issue-43106-gating-of-builtin-attrs.rs

@@ -35,18 +35,11 @@
 
 // check-pass
 
-#![feature(test, plugin_registrar)]
+#![feature(test)]
 #![warn(unused_attributes, unknown_lints)]
 //~^ NOTE the lint level is defined here
 //~| NOTE the lint level is defined here
 
-// Exception, a gated and deprecated attribute.
-
-#![plugin_registrar]
-//~^ WARN unused attribute
-//~| WARN use of deprecated attribute
-//~| HELP may be removed in a future compiler version
-
 // UNGATED WHITE-LISTED BUILT-IN ATTRIBUTES
 
 #![warn(x5400)] //~ WARN unknown lint: `x5400`
@@ -90,6 +83,7 @@
 #![crate_id = "10"]
 //~^ WARN use of deprecated attribute
 //~| HELP remove this attribute
+//~| NOTE `#[warn(deprecated)]` on by default
 
 // FIXME(#44232) we should warn that this isn't used.
 #![feature(rust1)]
@@ -219,35 +213,6 @@ mod macro_export {
     //~^ WARN unused attribute
 }
 
-#[plugin_registrar]
-//~^ WARN unused attribute
-//~| WARN use of deprecated attribute
-//~| HELP may be removed in a future compiler version
-mod plugin_registrar {
-    mod inner { #![plugin_registrar] }
-    //~^ WARN unused attribute
-    //~| WARN use of deprecated attribute
-    //~| HELP may be removed in a future compiler version
-    //~| NOTE `#[warn(deprecated)]` on by default
-
-    // for `fn f()` case, see gated-plugin_registrar.rs
-
-    #[plugin_registrar] struct S;
-    //~^ WARN unused attribute
-    //~| WARN use of deprecated attribute
-    //~| HELP may be removed in a future compiler version
-
-    #[plugin_registrar] type T = S;
-    //~^ WARN unused attribute
-    //~| WARN use of deprecated attribute
-    //~| HELP may be removed in a future compiler version
-
-    #[plugin_registrar] impl S { }
-    //~^ WARN unused attribute
-    //~| WARN use of deprecated attribute
-    //~| HELP may be removed in a future compiler version
-}
-
 // At time of unit test authorship, if compiling without `--test` then
 // non-crate-level #[test] attributes seem to be ignored.
 

src/test/ui/multiple-plugin-registrars.rs

@@ -1,12 +0,0 @@
-// error-pattern: multiple plugin registration functions found
-
-#![feature(plugin_registrar)]
-
-// the registration function isn't typechecked yet
-#[plugin_registrar]
-pub fn one() {}
-
-#[plugin_registrar]
-pub fn two() {}
-
-fn main() {}

src/test/ui/multiple-plugin-registrars.stderr

@@ -1,29 +0,0 @@
-warning: use of deprecated attribute `plugin_registrar`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
-  --> $DIR/multiple-plugin-registrars.rs:6:1
-   |
-LL | #[plugin_registrar]
-   | ^^^^^^^^^^^^^^^^^^^ help: may be removed in a future compiler version
-   |
-   = note: `#[warn(deprecated)]` on by default
-
-warning: use of deprecated attribute `plugin_registrar`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
-  --> $DIR/multiple-plugin-registrars.rs:9:1
-   |
-LL | #[plugin_registrar]
-   | ^^^^^^^^^^^^^^^^^^^ help: may be removed in a future compiler version
-
-error: multiple plugin registration functions found
-   |
-note: one is here
-  --> $DIR/multiple-plugin-registrars.rs:10:1
-   |
-LL | pub fn two() {}
-   | ^^^^^^^^^^^^^^^
-note: one is here
-  --> $DIR/multiple-plugin-registrars.rs:7:1
-   |
-LL | pub fn one() {}
-   | ^^^^^^^^^^^^^^^
-
-error: aborting due to previous error; 2 warnings emitted
-