Add test of remote with a packed struct

Currently fails to build:

    error: reference to packed field is unaligned
       --> test_suite/tests/test_gen.rs:858:10
        |
    858 | #[derive(Serialize, Deserialize)]
        |          ^^^^^^^^^
        |
    note: the lint level is defined here
       --> test_suite/tests/test_gen.rs:5:9
        |
    5   | #![deny(warnings)]
        |         ^^^^^^^^
        = note: `#[deny(unaligned_references)]` implied by `#[deny(warnings)]`
        = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
        = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
        = note: this error originates in the derive macro `Serialize` (in Nightly builds, run with -Z macro-backtrace for more info)

    error: reference to packed field is unaligned
       --> test_suite/tests/test_gen.rs:858:21
        |
    858 | #[derive(Serialize, Deserialize)]
        |                     ^^^^^^^^^^^
        |
        = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
        = note: fields of packed structs are not properly aligned, and creating a misaligned reference is undefined behavior (even if that reference is never dereferenced)
        = note: this error originates in the derive macro `Deserialize` (in Nightly builds, run with -Z macro-backtrace for more info)

Author: dtolnay

test_suite/tests/test_gen.rs

@@ -846,3 +846,19 @@ where
 {
     T::deserialize(deserializer)
 }
+
+//////////////////////////////////////////////////////////////////////////
+
+#[repr(packed)]
+pub struct RemotePacked {
+    pub a: u8,
+    pub b: u16,
+}
+
+#[derive(Serialize, Deserialize)]
+#[repr(packed)]
+#[serde(remote = "RemotePacked")]
+pub struct RemotePackedDef {
+    a: u8,
+    b: u16,
+}