From f861420a170f13900a5133b72da339d709f648e1 Mon Sep 17 00:00:00 2001
From: Tanner Rogalsky <tanner@tannerrogalsky.com>
Date: Sun, 17 May 2020 12:14:30 -0400
Subject: [PATCH 1/3] Add tests validating Serialize derivation for packed
 structs.

---
 test_suite/tests/test_macros.rs | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/test_suite/tests/test_macros.rs b/test_suite/tests/test_macros.rs
index c0c807ec7..bcd16b483 100644
--- a/test_suite/tests/test_macros.rs
+++ b/test_suite/tests/test_macros.rs
@@ -1878,3 +1878,19 @@ fn test_internally_tagged_newtype_variant_containing_unit_struct() {
         ],
     );
 }
+
+#[deny(safe_packed_borrows)]
+#[test]
+fn test_packed_struct_can_derive_serialize() {
+    #[derive(Copy, Clone, Serialize)]
+    #[repr(packed, C)]
+    struct PackedC {
+        t: f32,
+    }
+
+    #[derive(Copy, Clone, Serialize)]
+    #[repr(C, packed)]
+    struct CPacked {
+        t: f32,
+    }
+}

From 5806e6bb24eb389a628f2fd1c04423e46718ec26 Mon Sep 17 00:00:00 2001
From: Tanner Rogalsky <tanner@tannerrogalsky.com>
Date: Sun, 17 May 2020 12:14:42 -0400
Subject: [PATCH 2/3] Improved packed repr matching.

---
 serde_derive/src/internals/attr.rs | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/serde_derive/src/internals/attr.rs b/serde_derive/src/internals/attr.rs
index 44f757021..691a156d2 100644
--- a/serde_derive/src/internals/attr.rs
+++ b/serde_derive/src/internals/attr.rs
@@ -597,8 +597,19 @@ impl Container {
         for attr in &item.attrs {
             if attr.path.is_ident("repr") {
                 let _ = attr.parse_args_with(|input: ParseStream| {
-                    is_packed |= input.parse::<Ident>()? == "packed";
-                    Ok(())
+                    input.step(|cursor| {
+                        let mut rest = *cursor;
+                        while let Some((tt, next)) = rest.token_tree() {
+                            match &tt {
+                                TokenTree::Ident(ident) if ident == "packed" => {
+                                    is_packed |= true;
+                                    return Ok(((), next));
+                                }
+                                _ => rest = next,
+                            }
+                        }
+                        Err(cursor.error("no `packed` was found in the reprs"))
+                    })
                 });
             }
         }

From b7051208e0a344ef3b3d7ec675b9240666a9aa18 Mon Sep 17 00:00:00 2001
From: Tanner Rogalsky <tanner@tannerrogalsky.com>
Date: Tue, 19 May 2020 16:01:41 -0400
Subject: [PATCH 3/3] add alignment specific packed repr tests

---
 test_suite/tests/test_macros.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/test_suite/tests/test_macros.rs b/test_suite/tests/test_macros.rs
index bcd16b483..c6c0c1785 100644
--- a/test_suite/tests/test_macros.rs
+++ b/test_suite/tests/test_macros.rs
@@ -1893,4 +1893,16 @@ fn test_packed_struct_can_derive_serialize() {
     struct CPacked {
         t: f32,
     }
+
+    #[derive(Copy, Clone, Serialize)]
+    #[repr(C, packed(2))]
+    struct CPacked2 {
+        t: f32,
+    }
+
+    #[derive(Copy, Clone, Serialize)]
+    #[repr(packed(2), C)]
+    struct Packed2C {
+        t: f32,
+    }
 }