From f5e0fbcb141b2a111adf3bb16a5f1a4850ed70d3 Mon Sep 17 00:00:00 2001
From: bebecue <bebecue@proton.me>
Date: Sun, 5 Mar 2023 15:14:51 +0800
Subject: [PATCH 1/2] Make #[serde(alias)] works in #[serde(flatten)] context

fix #1504
---
 serde_derive/src/de.rs               |  3 ++-
 test_suite/tests/test_annotations.rs | 10 +++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/serde_derive/src/de.rs b/serde_derive/src/de.rs
index a703adaf7..679086e61 100644
--- a/serde_derive/src/de.rs
+++ b/serde_derive/src/de.rs
@@ -2400,7 +2400,8 @@ fn deserialize_struct_as_struct_visitor(
         .collect();
 
     let fields_stmt = {
-        let field_names = field_names_idents.iter().map(|(name, _, _)| name);
+        let field_names = field_names_idents.iter().flat_map(|(_, _, aliases)| aliases);
+
         quote_block! {
             const FIELDS: &'static [&'static str] = &[ #(#field_names),* ];
         }
diff --git a/test_suite/tests/test_annotations.rs b/test_suite/tests/test_annotations.rs
index f32c22c1a..75b7ffdd0 100644
--- a/test_suite/tests/test_annotations.rs
+++ b/test_suite/tests/test_annotations.rs
@@ -642,7 +642,7 @@ fn test_unknown_field_rename_struct() {
             Token::Str("a4"),
             Token::I32(3),
         ],
-        "unknown field `a4`, expected one of `a1`, `a2`, `a6`",
+        "unknown field `a4`, expected one of `a1`, `a3`, `a2`, `a5`, `a6`",
     );
 }
 
@@ -780,7 +780,7 @@ fn test_rename_enum() {
             Token::StructVariant {
                 name: "AliasEnum",
                 variant: "sailor_moon",
-                len: 3,
+                len: 5,
             },
             Token::Str("a"),
             Token::I8(0),
@@ -798,7 +798,7 @@ fn test_rename_enum() {
             Token::StructVariant {
                 name: "AliasEnum",
                 variant: "usagi_tsukino",
-                len: 3,
+                len: 5,
             },
             Token::Str("a"),
             Token::I8(0),
@@ -827,7 +827,7 @@ fn test_unknown_field_rename_enum() {
             Token::StructVariant {
                 name: "AliasEnum",
                 variant: "usagi_tsukino",
-                len: 3,
+                len: 5,
             },
             Token::Str("a"),
             Token::I8(0),
@@ -836,7 +836,7 @@ fn test_unknown_field_rename_enum() {
             Token::Str("d"),
             Token::I8(2),
         ],
-        "unknown field `d`, expected one of `a`, `b`, `f`",
+        "unknown field `d`, expected one of `a`, `c`, `b`, `e`, `f`",
     );
 }
 

From 01da3f79c9a41220174e8b7e89c3e836325e97ff Mon Sep 17 00:00:00 2001
From: bebecue <bebecue@proton.me>
Date: Tue, 7 Mar 2023 08:09:01 +0800
Subject: [PATCH 2/2] Add tests for #2387

---
 test_suite/tests/test_annotations.rs | 62 ++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/test_suite/tests/test_annotations.rs b/test_suite/tests/test_annotations.rs
index 75b7ffdd0..8ff725e01 100644
--- a/test_suite/tests/test_annotations.rs
+++ b/test_suite/tests/test_annotations.rs
@@ -2658,6 +2658,68 @@ fn test_flatten_any_after_flatten_struct() {
     );
 }
 
+#[test]
+fn test_alias_in_flatten_context() {
+    #[derive(Debug, PartialEq, Deserialize)]
+    struct Outer {
+        #[serde(flatten)]
+        a: AliasStruct,
+        b: i32,
+    }
+
+    assert_de_tokens(
+        &Outer {
+            a: AliasStruct {
+                a1: 1,
+                a2: 2,
+                a4: 4,
+            },
+            b: 7,
+        },
+        &[
+            Token::Struct {
+                name: "Outer",
+                len: 4,
+            },
+            Token::Str("a1"),
+            Token::I32(1),
+            Token::Str("a2"),
+            Token::I32(2),
+            Token::Str("a5"),
+            Token::I32(4),
+            Token::Str("b"),
+            Token::I32(7),
+            Token::StructEnd,
+        ],
+    );
+
+    assert_de_tokens(
+        &Outer {
+            a: AliasStruct {
+                a1: 1,
+                a2: 2,
+                a4: 4,
+            },
+            b: 7,
+        },
+        &[
+            Token::Struct {
+                name: "Outer",
+                len: 4,
+            },
+            Token::Str("a1"),
+            Token::I32(1),
+            Token::Str("a2"),
+            Token::I32(2),
+            Token::Str("a6"),
+            Token::I32(4),
+            Token::Str("b"),
+            Token::I32(7),
+            Token::StructEnd,
+        ],
+    );
+}
+
 #[test]
 fn test_expecting_message() {
     #[derive(Deserialize, PartialEq, Debug)]