1 files changed, 109 insertions, 0 deletions

diff --git a/vendor/memoffset/src/raw_field.rs b/vendor/memoffset/src/raw_field.rs
index a8dd2b359..e16df9f28 100644
--- a/vendor/memoffset/src/raw_field.rs
+++ b/vendor/memoffset/src/raw_field.rs
@@ -39,6 +39,21 @@ macro_rules! _memoffset__addr_of {
 }
 
 /// Deref-coercion protection macro.
+///
+/// Prevents complilation if the specified field name is not a part of the
+/// struct definition.
+///
+/// ```compile_fail
+/// use memoffset::_memoffset__field_check;
+///
+/// struct Foo {
+///     foo: i32,
+/// }
+///
+/// type BoxedFoo = Box<Foo>;
+///
+/// _memoffset__field_check!(BoxedFoo, foo);
+/// ```
 #[cfg(allow_clippy)]
 #[macro_export]
 #[doc(hidden)]
@@ -64,6 +79,25 @@ macro_rules! _memoffset__field_check {
 }
 
 /// Deref-coercion protection macro.
+///
+/// Prevents complilation if the specified type is not a tuple.
+///
+/// ```compile_fail
+/// use memoffset::_memoffset__field_check_tuple;
+///
+/// _memoffset__field_check_tuple!(i32, 0);
+/// ```
+#[cfg(allow_clippy)]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__field_check_tuple {
+    ($type:ty, $field:tt) => {
+        // Make sure the type argument is a tuple
+        #[allow(clippy::unneeded_wildcard_pattern)]
+        let (_, ..): $type;
+    };
+}
+#[cfg(not(allow_clippy))]
 #[macro_export]
 #[doc(hidden)]
 macro_rules! _memoffset__field_check_tuple {
@@ -73,6 +107,53 @@ macro_rules! _memoffset__field_check_tuple {
     };
 }
 
+/// Deref-coercion protection macro for unions.
+/// Unfortunately accepts single-field structs as well, which is not ideal,
+/// but ultimately pretty harmless.
+///
+/// ```compile_fail
+/// use memoffset::_memoffset__field_check_union;
+///
+/// union Foo {
+///     variant_a: i32,
+/// }
+///
+/// type BoxedFoo = Box<Foo>;
+///
+/// _memoffset__field_check_union!(BoxedFoo, variant_a);
+/// ```
+#[cfg(allow_clippy)]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__field_check_union {
+    ($type:path, $field:tt) => {
+        // Make sure the field actually exists. This line ensures that a
+        // compile-time error is generated if $field is accessed through a
+        // Deref impl.
+        #[allow(clippy::unneeded_wildcard_pattern)]
+        // rustc1.19 requires unsafe here for the pattern; not needed in newer versions
+        #[allow(unused_unsafe)]
+        unsafe {
+            let $type { $field: _ };
+        }
+    };
+}
+#[cfg(not(allow_clippy))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__field_check_union {
+    ($type:path, $field:tt) => {
+        // Make sure the field actually exists. This line ensures that a
+        // compile-time error is generated if $field is accessed through a
+        // Deref impl.
+        // rustc1.19 requires unsafe here for the pattern; not needed in newer versions
+        #[allow(unused_unsafe)]
+        unsafe {
+            let $type { $field: _ };
+        }
+    };
+}
+
 /// Computes a const raw pointer to the given field of the given base pointer
 /// to the given parent type.
 ///
@@ -115,3 +196,31 @@ macro_rules! raw_field_tuple {
         }
     }};
 }
+
+/// Computes a const raw pointer to the given field of the given base pointer
+/// to the given parent tuple typle.
+///
+/// The `base` pointer *must not* be dangling, but it *may* point to
+/// uninitialized memory.
+///
+/// ## Note
+/// This macro is the same as `raw_field`, except for a different Deref-coercion check that
+/// supports unions.
+/// Due to macro_rules limitations, this check will accept structs with a single field as well as unions.
+/// This is not a stable guarantee, and future versions of this crate might fail
+/// on any use of this macro with a struct, without a semver bump.
+#[macro_export(local_inner_macros)]
+macro_rules! raw_field_union {
+    ($base:expr, $parent:path, $field:tt) => {{
+        _memoffset__field_check_union!($parent, $field);
+        let base = $base; // evaluate $base outside the `unsafe` block
+
+        // Get the field address.
+        // Crucially, we know that this will not trigger a deref coercion because
+        // of the field check we did above.
+        #[allow(unused_unsafe)] // for when the macro is used in an unsafe block
+        unsafe {
+            _memoffset__addr_of!((*(base as *const $parent)).$field)
+        }
+    }};
+}