Rollup merge of #64139 - Mark-Simulacrum:strip-legacy-proc-macro, r=petrochenkov

Migrate internal diagnostic registration to macro_rules

Review is best done commit-by-commit.

Fixes #64132.

1 files changed, 0 insertions, 6 deletions

diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 1741932c1b8..49efbce482f 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -18,7 +18,6 @@
 #![feature(proc_macro_diagnostic)]
 #![feature(proc_macro_internals)]
 #![feature(proc_macro_span)]
-#![feature(rustc_diagnostic_macros)]
 #![feature(try_trait)]
 #![feature(unicode_internals)]
 
@@ -123,11 +122,8 @@ scoped_tls::scoped_thread_local!(pub static GLOBALS: Globals);
 pub mod diagnostics {
     #[macro_use]
     pub mod macros;
-    pub mod plugin;
 }
 
-// N.B., this module needs to be declared first so diagnostics are
-// registered before they are used.
 pub mod error_codes;
 
 pub mod util {
@@ -182,5 +178,3 @@ pub mod ext {
 }
 
 pub mod early_buffered_lints;
-
-__build_diagnostic_array! { libsyntax, DIAGNOSTICS }