Vendor things

third-party/vendor/zerocopy-derive/tests/union_as_bytes.rs

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+// Copyright 2019 The Fuchsia Authors
+//
+// Licensed under a BSD-style license <LICENSE-BSD>, Apache License, Version 2.0
+// <LICENSE-APACHE or https://www.apache.org/licenses/LICENSE-2.0>, or the MIT
+// license <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your option.
+// This file may not be copied, modified, or distributed except according to
+// those terms.
+
+#![allow(warnings)]
+
+use std::{marker::PhantomData, option::IntoIter};
+
+use {static_assertions::assert_impl_all, zerocopy::AsBytes};
+
+// A union is `AsBytes` if:
+// - all fields are `AsBytes`
+// - `repr(C)` or `repr(transparent)` and
+//   - no padding (size of union equals size of each field type)
+// - `repr(packed)`
+
+#[derive(AsBytes, Clone, Copy)]
+#[repr(C)]
+union CZst {
+    a: (),
+}
+
+assert_impl_all!(CZst: AsBytes);
+
+#[derive(AsBytes)]
+#[repr(C)]
+union C {
+    a: u8,
+    b: u8,
+}
+
+assert_impl_all!(C: AsBytes);
+
+// Transparent unions are unstable; see issue #60405
+// <https://github.com/rust-lang/rust/issues/60405> for more information.
+
+// #[derive(AsBytes)]
+// #[repr(transparent)]
+// union Transparent {
+//     a: u8,
+//     b: CZst,
+// }
+
+// is_as_bytes!(Transparent);
+
+#[derive(AsBytes)]
+#[repr(C, packed)]
+union CZstPacked {
+    a: (),
+}
+
+assert_impl_all!(CZstPacked: AsBytes);
+
+#[derive(AsBytes)]
+#[repr(C, packed)]
+union CPacked {
+    a: u8,
+    b: i8,
+}
+
+assert_impl_all!(CPacked: AsBytes);
+
+#[derive(AsBytes)]
+#[repr(C, packed)]
+union CMultibytePacked {
+    a: i32,
+    b: u32,
+    c: f32,
+}
+
+assert_impl_all!(CMultibytePacked: AsBytes);