From d7e72b33d1091049ca8d08b36453e91f3b46f0c6 Mon Sep 17 00:00:00 2001
From: Armani Ferrante <armaniferrante@gmail.com>
Date: Sun, 9 Jan 2022 16:19:41 -0500
Subject: [PATCH] lang: repr override for zero copy (#1273)

---
 lang/attribute/account/src/lib.rs             | 14 +++++++++++++-
 tests/zero-copy/programs/zero-copy/src/lib.rs |  1 +
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/lang/attribute/account/src/lib.rs b/lang/attribute/account/src/lib.rs
index da1dd8bd..4ea13811 100644
--- a/lang/attribute/account/src/lib.rs
+++ b/lang/attribute/account/src/lib.rs
@@ -291,9 +291,21 @@ pub fn zero_copy(
 ) -> proc_macro::TokenStream {
     let account_strct = parse_macro_input!(item as syn::ItemStruct);
 
+    // Takes the first repr. It's assumed that more than one are not on the
+    // struct.
+    let attr = account_strct
+        .attrs
+        .iter()
+        .find(|attr| anchor_syn::parser::tts_to_string(&attr.path) == "repr");
+
+    let repr = match attr {
+        Some(_attr) => quote! {},
+        None => quote! {#[repr(C)]},
+    };
+
     proc_macro::TokenStream::from(quote! {
         #[derive(anchor_lang::__private::ZeroCopyAccessor, Copy, Clone)]
-        #[repr(C)]
+        #repr
         #account_strct
     })
 }
diff --git a/tests/zero-copy/programs/zero-copy/src/lib.rs b/tests/zero-copy/programs/zero-copy/src/lib.rs
index d029d521..05927688 100644
--- a/tests/zero-copy/programs/zero-copy/src/lib.rs
+++ b/tests/zero-copy/programs/zero-copy/src/lib.rs
@@ -139,6 +139,7 @@ pub struct UpdateLargeAccount<'info> {
 
 #[account(zero_copy)]
 #[derive(Default)]
+#[repr(packed)]
 pub struct Foo {
     pub authority: Pubkey,
     pub data: u64,