From 81136cb391135e7a2817316268f0795e7350f5ea Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Wed, 4 Oct 2023 16:21:02 +1100
Subject: [PATCH 1/2] Sort `compiler/rustc_attr/Cargo.toml` dependencies.

It's easier to read in sorted order.
---
 compiler/rustc_attr/Cargo.toml | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/compiler/rustc_attr/Cargo.toml b/compiler/rustc_attr/Cargo.toml
index 2c4c3a0c2635b..a14d279681792 100644
--- a/compiler/rustc_attr/Cargo.toml
+++ b/compiler/rustc_attr/Cargo.toml
@@ -6,14 +6,14 @@ edition = "2021"
 [lib]
 
 [dependencies]
+rustc_ast = { path = "../rustc_ast" }
 rustc_ast_pretty = { path = "../rustc_ast_pretty" }
-rustc_serialize = { path = "../rustc_serialize" }
-rustc_errors = { path = "../rustc_errors" }
-rustc_fluent_macro = { path = "../rustc_fluent_macro" }
-rustc_span = { path = "../rustc_span" }
 rustc_data_structures = { path = "../rustc_data_structures" }
+rustc_errors = { path = "../rustc_errors" }
 rustc_feature = { path = "../rustc_feature" }
+rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_lexer = { path = "../rustc_lexer" }
 rustc_macros = { path = "../rustc_macros" }
+rustc_serialize = { path = "../rustc_serialize" }
 rustc_session = { path = "../rustc_session" }
-rustc_ast = { path = "../rustc_ast" }
+rustc_span = { path = "../rustc_span" }

From 0ece171c2f7f96ca9bd445fbac3c1b0c4402af14 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Wed, 4 Oct 2023 17:20:15 +1100
Subject: [PATCH 2/2] Remove E0551.

Because it's the same as E0539.

Fixes #51489.
---
 compiler/rustc_attr/src/builtin.rs                  |  2 +-
 compiler/rustc_attr/src/session_diagnostics.rs      |  9 ---------
 compiler/rustc_error_codes/src/error_codes/E0551.md |  4 +++-
 tests/ui/deprecation/deprecation-sanity.stderr      | 10 +++++-----
 4 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/compiler/rustc_attr/src/builtin.rs b/compiler/rustc_attr/src/builtin.rs
index ca4b3662a089f..3ffb4b83f20a2 100644
--- a/compiler/rustc_attr/src/builtin.rs
+++ b/compiler/rustc_attr/src/builtin.rs
@@ -846,7 +846,7 @@ pub fn find_deprecation(
                                 ),
                             );
                         } else {
-                            sess.emit_err(session_diagnostics::IncorrectMetaItem2 {
+                            sess.emit_err(session_diagnostics::IncorrectMetaItem {
                                 span: meta.span,
                             });
                         }
diff --git a/compiler/rustc_attr/src/session_diagnostics.rs b/compiler/rustc_attr/src/session_diagnostics.rs
index ee79545e304ae..86f27254db25c 100644
--- a/compiler/rustc_attr/src/session_diagnostics.rs
+++ b/compiler/rustc_attr/src/session_diagnostics.rs
@@ -165,15 +165,6 @@ pub(crate) struct MissingIssue {
     pub span: Span,
 }
 
-// FIXME: This diagnostic is identical to `IncorrectMetaItem`, barring the error code. Consider
-// changing this to `IncorrectMetaItem`. See #51489.
-#[derive(Diagnostic)]
-#[diag(attr_incorrect_meta_item, code = "E0551")]
-pub(crate) struct IncorrectMetaItem2 {
-    #[primary_span]
-    pub span: Span,
-}
-
 // FIXME: Why is this the same error code as `InvalidReprHintNoParen` and `InvalidReprHintNoValue`?
 // It is more similar to `IncorrectReprFormatGeneric`.
 #[derive(Diagnostic)]
diff --git a/compiler/rustc_error_codes/src/error_codes/E0551.md b/compiler/rustc_error_codes/src/error_codes/E0551.md
index 53db559a4fcbf..0e078fe71bfd1 100644
--- a/compiler/rustc_error_codes/src/error_codes/E0551.md
+++ b/compiler/rustc_error_codes/src/error_codes/E0551.md
@@ -1,8 +1,10 @@
+#### Note: this error code is no longer emitted by the compiler
+
 An invalid meta-item was used inside an attribute.
 
 Erroneous code example:
 
-```compile_fail,E0551
+```compile_fail,E0539
 #[deprecated(note)] // error!
 fn i_am_deprecated() {}
 ```
diff --git a/tests/ui/deprecation/deprecation-sanity.stderr b/tests/ui/deprecation/deprecation-sanity.stderr
index 8b2b480d19586..383212ad9b4b8 100644
--- a/tests/ui/deprecation/deprecation-sanity.stderr
+++ b/tests/ui/deprecation/deprecation-sanity.stderr
@@ -16,25 +16,25 @@ error[E0541]: unknown meta item 'reason'
 LL |     #[deprecated(since = "a", note = "a", reason)]
    |                                           ^^^^^^ expected one of `since`, `note`
 
-error[E0551]: incorrect meta item
+error[E0539]: incorrect meta item
   --> $DIR/deprecation-sanity.rs:7:31
    |
 LL |     #[deprecated(since = "a", note)]
    |                               ^^^^
 
-error[E0551]: incorrect meta item
+error[E0539]: incorrect meta item
   --> $DIR/deprecation-sanity.rs:10:18
    |
 LL |     #[deprecated(since, note = "a")]
    |                  ^^^^^
 
-error[E0551]: incorrect meta item
+error[E0539]: incorrect meta item
   --> $DIR/deprecation-sanity.rs:13:31
    |
 LL |     #[deprecated(since = "a", note(b))]
    |                               ^^^^^^^
 
-error[E0551]: incorrect meta item
+error[E0539]: incorrect meta item
   --> $DIR/deprecation-sanity.rs:16:18
    |
 LL |     #[deprecated(since(b), note = "a")]
@@ -70,5 +70,5 @@ LL | #[deprecated = "hello"]
 
 error: aborting due to 10 previous errors
 
-Some errors have detailed explanations: E0538, E0541, E0551, E0565.
+Some errors have detailed explanations: E0538, E0539, E0541, E0565.
 For more information about an error, try `rustc --explain E0538`.