rustc_plugin: Some further cleanup

Remove a useless test

src/librustc_interface/passes.rs

@@ -30,7 +30,6 @@ use rustc_mir as mir;
 use rustc_parse::{parse_crate_from_file, parse_crate_from_source_str};
 use rustc_passes::{self, ast_validation, hir_stats, layout_test};
 use rustc_plugin_impl as plugin;
-use rustc_plugin_impl::registry::Registry;
 use rustc_privacy;
 use rustc_resolve::{Resolver, ResolverArenas};
 use rustc_traits;
@@ -218,7 +217,7 @@ pub fn register_plugins<'a>(
         plugin::load::load_plugins(sess, metadata_loader, &krate)
     });
     time(sess, "plugin registration", || {
-        let mut registry = Registry::new(sess, &mut lint_store, krate.span);
+        let mut registry = plugin::Registry { lint_store: &mut lint_store };
         for registrar in registrars {
             registrar(&mut registry);
         }

src/librustc_plugin_impl/lib.rs

@@ -10,10 +10,16 @@
 
 #![feature(nll)]
 
-#![recursion_limit="256"]
+use rustc::lint::LintStore;
 
-pub use registry::Registry;
-
-pub mod registry;
-pub mod load;
 pub mod build;
+pub mod load;
+
+/// Structure used to register plugins.
+///
+/// A plugin registrar function takes an `&mut Registry` and should call
+/// methods to register its plugins.
+pub struct Registry<'a> {
+    /// The `LintStore` allows plugins to register new lints.
+    pub lint_store: &'a mut LintStore,
+}

src/librustc_plugin_impl/load.rs

@@ -3,7 +3,7 @@
 use rustc::middle::cstore::MetadataLoader;
 use rustc::session::Session;
 use rustc_metadata::locator;
-use crate::registry::Registry;
+use crate::Registry;
 
 use std::borrow::ToOwned;
 use std::env;

src/test/ui-fulldeps/plugin-args-2.stderr → src/test/ui-fulldeps/plugin-args.stderr

@@ -1,11 +1,11 @@
 error[E0498]: malformed `plugin` attribute
-  --> $DIR/plugin-args-2.rs:5:11
+  --> $DIR/plugin-args.rs:5:11
    |
 LL | #![plugin(empty_plugin(args))]
    |           ^^^^^^^^^^^^^^^^^^ malformed attribute
 
 warning: use of deprecated attribute `plugin`: compiler plugins are deprecated. See https://github.com/rust-lang/rust/pull/64675
-  --> $DIR/plugin-args-2.rs:5:1
+  --> $DIR/plugin-args.rs:5:1
    |
 LL | #![plugin(empty_plugin(args))]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: may be removed in a future compiler version