1 files changed, 81 insertions, 17 deletions
diff --git a/tests/struct_as_bytes.rs b/tests/struct_as_bytes.rs
index fd464ce..e1507aa 100644
--- a/tests/struct_as_bytes.rs
+++ b/tests/struct_as_bytes.rs
@@ -4,20 +4,13 @@
 
 #![allow(warnings)]
 
-use std::{marker::PhantomData, option::IntoIter};
+mod util;
 
-use zerocopy::AsBytes;
+use std::{marker::PhantomData, mem::ManuallyDrop, option::IntoIter};
 
-struct IsAsBytes<T: AsBytes>(T);
+use {static_assertions::assert_impl_all, zerocopy::AsBytes};
 
-// Fail compilation if `$ty: !AsBytes`.
-macro_rules! is_as_bytes {
-    ($ty:ty) => {
-        const _: () = {
-            let _: IsAsBytes<$ty>;
-        };
-    };
-}
+use self::util::AU16;
 
 // A struct is `AsBytes` if:
 // - all fields are `AsBytes`
@@ -29,17 +22,17 @@ macro_rules! is_as_bytes {
 #[repr(C)]
 struct CZst;
 
-is_as_bytes!(CZst);
+assert_impl_all!(CZst: AsBytes);
 
 #[derive(AsBytes)]
 #[repr(C)]
 struct C {
     a: u8,
     b: u8,
-    c: u16,
+    c: AU16,
 }
 
-is_as_bytes!(C);
+assert_impl_all!(C: AsBytes);
 
 #[derive(AsBytes)]
 #[repr(transparent)]
@@ -48,19 +41,90 @@ struct Transparent {
     b: CZst,
 }
 
-is_as_bytes!(Transparent);
+assert_impl_all!(Transparent: AsBytes);
+
+#[derive(AsBytes)]
+#[repr(transparent)]
+struct TransparentGeneric<T: ?Sized> {
+    a: CZst,
+    b: T,
+}
+
+assert_impl_all!(TransparentGeneric<u64>: AsBytes);
+assert_impl_all!(TransparentGeneric<[u64]>: AsBytes);
 
 #[derive(AsBytes)]
 #[repr(C, packed)]
 struct CZstPacked;
 
-is_as_bytes!(CZstPacked);
+assert_impl_all!(CZstPacked: AsBytes);
 
 #[derive(AsBytes)]
 #[repr(C, packed)]
 struct CPacked {
     a: u8,
+    // NOTE: The `u16` type is not guaranteed to have alignment 2, although it
+    // does on many platforms. However, to fix this would require a custom type
+    // with a `#[repr(align(2))]` attribute, and `#[repr(packed)]` types are not
+    // allowed to transitively contain `#[repr(align(...))]` types. Thus, we
+    // have no choice but to use `u16` here. Luckily, these tests run in CI on
+    // platforms on which `u16` has alignment 2, so this isn't that big of a
+    // deal.
+    b: u16,
+}
+
+assert_impl_all!(CPacked: AsBytes);
+
+#[derive(AsBytes)]
+#[repr(C, packed)]
+struct CPackedGeneric<T, U: ?Sized> {
+    t: T,
+    // Unsized types stored in `repr(packed)` structs must not be dropped
+    // because dropping them in-place might be unsound depending on the
+    // alignment of the outer struct. Sized types can be dropped by first being
+    // moved to an aligned stack variable, but this isn't possible with unsized
+    // types.
+    u: ManuallyDrop<U>,
+}
+
+assert_impl_all!(CPackedGeneric<u8, AU16>: AsBytes);
+assert_impl_all!(CPackedGeneric<u8, [AU16]>: AsBytes);
+
+#[derive(AsBytes)]
+#[repr(packed)]
+struct Packed {
+    a: u8,
+    // NOTE: The `u16` type is not guaranteed to have alignment 2, although it
+    // does on many platforms. However, to fix this would require a custom type
+    // with a `#[repr(align(2))]` attribute, and `#[repr(packed)]` types are not
+    // allowed to transitively contain `#[repr(align(...))]` types. Thus, we
+    // have no choice but to use `u16` here. Luckily, these tests run in CI on
+    // platforms on which `u16` has alignment 2, so this isn't that big of a
+    // deal.
     b: u16,
 }
 
-is_as_bytes!(CPacked);
+assert_impl_all!(Packed: AsBytes);
+
+#[derive(AsBytes)]
+#[repr(packed)]
+struct PackedGeneric<T, U: ?Sized> {
+    t: T,
+    // Unsized types stored in `repr(packed)` structs must not be dropped
+    // because dropping them in-place might be unsound depending on the
+    // alignment of the outer struct. Sized types can be dropped by first being
+    // moved to an aligned stack variable, but this isn't possible with unsized
+    // types.
+    u: ManuallyDrop<U>,
+}
+
+assert_impl_all!(PackedGeneric<u8, AU16>: AsBytes);
+assert_impl_all!(PackedGeneric<u8, [AU16]>: AsBytes);
+
+#[derive(AsBytes)]
+#[repr(transparent)]
+struct Unsized {
+    a: [u8],
+}
+
+assert_impl_all!(Unsized: AsBytes);