Merging upstream version 1.67.1+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

4 files changed, 747 insertions, 0 deletions

diff --git a/vendor/memoffset-0.6.5/src/lib.rs b/vendor/memoffset-0.6.5/src/lib.rs
new file mode 100644
index 000000000..d80ff1743
--- /dev/null
+++ b/vendor/memoffset-0.6.5/src/lib.rs
@@ -0,0 +1,92 @@
+// Copyright (c) 2017 Gilad Naaman
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+//! A crate used for calculating offsets of struct members and their spans.
+//!
+//! This functionality currently can not be used in compile time code such as `const` or `const fn` definitions.
+//!
+//! ## Examples
+//! ```
+//! use memoffset::{offset_of, span_of};
+//!
+//! #[repr(C, packed)]
+//! struct HelpMeIAmTrappedInAStructFactory {
+//!     help_me_before_they_: [u8; 15],
+//!     a: u32
+//! }
+//!
+//! fn main() {
+//!     assert_eq!(offset_of!(HelpMeIAmTrappedInAStructFactory, a), 15);
+//!     assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, a), 15..19);
+//!     assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, help_me_before_they_ .. a), 0..15);
+//! }
+//! ```
+//!
+//! This functionality can be useful, for example, for checksum calculations:
+//!
+//! ```ignore
+//! #[repr(C, packed)]
+//! struct Message {
+//!     header: MessageHeader,
+//!     fragment_index: u32,
+//!     fragment_count: u32,
+//!     payload: [u8; 1024],
+//!     checksum: u16
+//! }
+//!
+//! let checksum_range = &raw[span_of!(Message, header..checksum)];
+//! let checksum = crc16(checksum_range);
+//! ```
+
+#![no_std]
+#![cfg_attr(
+    feature = "unstable_const",
+    feature(const_ptr_offset_from, const_refs_to_cell)
+)]
+
+#[macro_use]
+#[cfg(doctests)]
+#[cfg(doctest)]
+extern crate doc_comment;
+#[cfg(doctests)]
+#[cfg(doctest)]
+doctest!("../README.md");
+
+/// Hidden module for things the macros need to access.
+#[doc(hidden)]
+pub mod __priv {
+    #[doc(hidden)]
+    pub use core::mem;
+    #[doc(hidden)]
+    pub use core::ptr;
+
+    /// Use type inference to obtain the size of the pointee (without actually using the pointer).
+    #[doc(hidden)]
+    pub fn size_of_pointee<T>(_ptr: *const T) -> usize {
+        mem::size_of::<T>()
+    }
+}
+
+#[macro_use]
+mod raw_field;
+#[macro_use]
+mod offset_of;
+#[macro_use]
+mod span_of;
diff --git a/vendor/memoffset-0.6.5/src/offset_of.rs b/vendor/memoffset-0.6.5/src/offset_of.rs
new file mode 100644
index 000000000..8596e45cf
--- /dev/null
+++ b/vendor/memoffset-0.6.5/src/offset_of.rs
@@ -0,0 +1,282 @@
+// Copyright (c) 2017 Gilad Naaman
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+/// Macro to create a local `base_ptr` raw pointer of the given type, avoiding UB as
+/// much as is possible currently.
+#[cfg(maybe_uninit)]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__let_base_ptr {
+    ($name:ident, $type:ty) => {
+        // No UB here, and the pointer does not dangle, either.
+        // But we have to make sure that `uninit` lives long enough,
+        // so it has to be in the same scope as `$name`. That's why
+        // `let_base_ptr` declares a variable (several, actually)
+        // instead of returning one.
+        let uninit = $crate::__priv::mem::MaybeUninit::<$type>::uninit();
+        let $name: *const $type = uninit.as_ptr();
+    };
+}
+#[cfg(not(maybe_uninit))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__let_base_ptr {
+    ($name:ident, $type:ty) => {
+        // No UB right here, but we will later dereference this pointer to
+        // offset into a field, and that is UB because the pointer is dangling.
+        let $name = $crate::__priv::mem::align_of::<$type>() as *const $type;
+    };
+}
+
+/// Macro to compute the distance between two pointers.
+#[cfg(feature = "unstable_const")]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset_offset_from_unsafe {
+    ($field:expr, $base:expr) => {{
+        let field = $field; // evaluate $field outside the `unsafe` block
+        let base = $base; // evaluate $base outside the `unsafe` block
+        // Compute offset, with unstable `offset_from` for const-compatibility.
+        // (Requires the pointers to not dangle, but we already need that for `raw_field!` anyway.)
+        unsafe { (field as *const u8).offset_from(base as *const u8) as usize }
+    }};
+}
+#[cfg(not(feature = "unstable_const"))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset_offset_from_unsafe {
+    ($field:expr, $base:expr) => {
+        // Compute offset.
+        ($field as usize) - ($base as usize)
+    };
+}
+
+/// Calculates the offset of the specified field from the start of the named struct.
+///
+/// ## Examples
+/// ```
+/// use memoffset::offset_of;
+///
+/// #[repr(C, packed)]
+/// struct Foo {
+///     a: u32,
+///     b: u64,
+///     c: [u8; 5]
+/// }
+///
+/// fn main() {
+///     assert_eq!(offset_of!(Foo, a), 0);
+///     assert_eq!(offset_of!(Foo, b), 4);
+/// }
+/// ```
+#[macro_export(local_inner_macros)]
+macro_rules! offset_of {
+    ($parent:path, $field:tt) => {{
+        // Get a base pointer (non-dangling if rustc supports `MaybeUninit`).
+        _memoffset__let_base_ptr!(base_ptr, $parent);
+        // Get field pointer.
+        let field_ptr = raw_field!(base_ptr, $parent, $field);
+        // Compute offset.
+        _memoffset_offset_from_unsafe!(field_ptr, base_ptr)
+    }};
+}
+
+/// Calculates the offset of the specified field from the start of the tuple.
+///
+/// ## Examples
+/// ```
+/// use memoffset::offset_of_tuple;
+///
+/// fn main() {
+///     assert!(offset_of_tuple!((u8, u32), 1) >= 0, "Tuples do not have a defined layout");
+/// }
+/// ```
+#[cfg(tuple_ty)]
+#[macro_export(local_inner_macros)]
+macro_rules! offset_of_tuple {
+    ($parent:ty, $field:tt) => {{
+        // Get a base pointer (non-dangling if rustc supports `MaybeUninit`).
+        _memoffset__let_base_ptr!(base_ptr, $parent);
+        // Get field pointer.
+        let field_ptr = raw_field_tuple!(base_ptr, $parent, $field);
+        // Compute offset.
+        _memoffset_offset_from_unsafe!(field_ptr, base_ptr)
+    }};
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn offset_simple() {
+        #[repr(C)]
+        struct Foo {
+            a: u32,
+            b: [u8; 2],
+            c: i64,
+        }
+
+        assert_eq!(offset_of!(Foo, a), 0);
+        assert_eq!(offset_of!(Foo, b), 4);
+        assert_eq!(offset_of!(Foo, c), 8);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)] // this creates unaligned references
+    fn offset_simple_packed() {
+        #[repr(C, packed)]
+        struct Foo {
+            a: u32,
+            b: [u8; 2],
+            c: i64,
+        }
+
+        assert_eq!(offset_of!(Foo, a), 0);
+        assert_eq!(offset_of!(Foo, b), 4);
+        assert_eq!(offset_of!(Foo, c), 6);
+    }
+
+    #[test]
+    fn tuple_struct() {
+        #[repr(C)]
+        struct Tup(i32, i32);
+
+        assert_eq!(offset_of!(Tup, 0), 0);
+        assert_eq!(offset_of!(Tup, 1), 4);
+    }
+
+    #[test]
+    fn path() {
+        mod sub {
+            #[repr(C)]
+            pub struct Foo {
+                pub x: u32,
+            }
+        }
+
+        assert_eq!(offset_of!(sub::Foo, x), 0);
+    }
+
+    #[test]
+    fn inside_generic_method() {
+        struct Pair<T, U>(T, U);
+
+        fn foo<T, U>(_: Pair<T, U>) -> usize {
+            offset_of!(Pair<T, U>, 1)
+        }
+
+        assert_eq!(foo(Pair(0, 0)), 4);
+    }
+
+    #[cfg(tuple_ty)]
+    #[test]
+    fn test_tuple_offset() {
+        let f = (0i32, 0.0f32, 0u8);
+        let f_ptr = &f as *const _;
+        let f1_ptr = &f.1 as *const _;
+
+        assert_eq!(
+            f1_ptr as usize - f_ptr as usize,
+            offset_of_tuple!((i32, f32, u8), 1)
+        );
+    }
+
+    #[test]
+    fn test_raw_field() {
+        #[repr(C)]
+        struct Foo {
+            a: u32,
+            b: [u8; 2],
+            c: i64,
+        }
+
+        let f: Foo = Foo {
+            a: 0,
+            b: [0, 0],
+            c: 0,
+        };
+        let f_ptr = &f as *const _;
+        assert_eq!(f_ptr as usize + 0, raw_field!(f_ptr, Foo, a) as usize);
+        assert_eq!(f_ptr as usize + 4, raw_field!(f_ptr, Foo, b) as usize);
+        assert_eq!(f_ptr as usize + 8, raw_field!(f_ptr, Foo, c) as usize);
+    }
+
+    #[cfg(tuple_ty)]
+    #[test]
+    fn test_raw_field_tuple() {
+        let t = (0u32, 0u8, false);
+        let t_ptr = &t as *const _;
+        let t_addr = t_ptr as usize;
+
+        assert_eq!(
+            &t.0 as *const _ as usize - t_addr,
+            raw_field_tuple!(t_ptr, (u32, u8, bool), 0) as usize - t_addr
+        );
+        assert_eq!(
+            &t.1 as *const _ as usize - t_addr,
+            raw_field_tuple!(t_ptr, (u32, u8, bool), 1) as usize - t_addr
+        );
+        assert_eq!(
+            &t.2 as *const _ as usize - t_addr,
+            raw_field_tuple!(t_ptr, (u32, u8, bool), 2) as usize - t_addr
+        );
+    }
+
+    #[cfg(feature = "unstable_const")]
+    #[test]
+    fn const_offset() {
+        #[repr(C)]
+        struct Foo {
+            a: u32,
+            b: [u8; 2],
+            c: i64,
+        }
+
+        assert_eq!([0; offset_of!(Foo, b)].len(), 4);
+    }
+
+    #[cfg(feature = "unstable_const")]
+    #[test]
+    fn const_offset_interior_mutable() {
+        #[repr(C)]
+        struct Foo {
+            a: u32,
+            b: core::cell::Cell<u32>,
+        }
+
+        assert_eq!([0; offset_of!(Foo, b)].len(), 4);
+    }
+
+    #[cfg(feature = "unstable_const")]
+    #[test]
+    fn const_fn_offset() {
+        const fn test_fn() -> usize {
+            #[repr(C)]
+            struct Foo {
+                a: u32,
+                b: [u8; 2],
+                c: i64,
+            }
+
+            offset_of!(Foo, b)
+        }
+
+        assert_eq!([0; test_fn()].len(), 4);
+    }
+}
diff --git a/vendor/memoffset-0.6.5/src/raw_field.rs b/vendor/memoffset-0.6.5/src/raw_field.rs
new file mode 100644
index 000000000..a8dd2b359
--- /dev/null
+++ b/vendor/memoffset-0.6.5/src/raw_field.rs
@@ -0,0 +1,117 @@
+// Copyright (c) 2020 Gilad Naaman, Ralf Jung
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+/// `addr_of!`, or just ref-then-cast when that is not available.
+#[cfg(raw_ref_macros)]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__addr_of {
+    ($path:expr) => {{
+        $crate::__priv::ptr::addr_of!($path)
+    }};
+}
+#[cfg(not(raw_ref_macros))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__addr_of {
+    ($path:expr) => {{
+        // This is UB because we create an intermediate reference to uninitialized memory.
+        // Nothing we can do about that without `addr_of!` though.
+        &$path as *const _
+    }};
+}
+
+/// Deref-coercion protection macro.
+#[cfg(allow_clippy)]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__field_check {
+    ($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_field_pattern)]
+        let $type { $field: _, .. };
+    };
+}
+#[cfg(not(allow_clippy))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__field_check {
+    ($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.
+        let $type { $field: _, .. };
+    };
+}
+
+/// Deref-coercion protection macro.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! _memoffset__field_check_tuple {
+    ($type:ty, $field:tt) => {
+        // Make sure the type argument is a tuple
+        let (_, ..): $type;
+    };
+}
+
+/// Computes a const raw pointer to the given field of the given base pointer
+/// to the given parent type.
+///
+/// The `base` pointer *must not* be dangling, but it *may* point to
+/// uninitialized memory.
+#[macro_export(local_inner_macros)]
+macro_rules! raw_field {
+    ($base:expr, $parent:path, $field:tt) => {{
+        _memoffset__field_check!($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)
+        }
+    }};
+}
+
+/// 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.
+#[cfg(tuple_ty)]
+#[macro_export(local_inner_macros)]
+macro_rules! raw_field_tuple {
+    ($base:expr, $parent:ty, $field:tt) => {{
+        _memoffset__field_check_tuple!($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)
+        }
+    }};
+}
diff --git a/vendor/memoffset-0.6.5/src/span_of.rs b/vendor/memoffset-0.6.5/src/span_of.rs
new file mode 100644
index 000000000..aab9d0aca
--- /dev/null
+++ b/vendor/memoffset-0.6.5/src/span_of.rs
@@ -0,0 +1,256 @@
+// Copyright (c) 2017 Gilad Naaman
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+/// Reexport for `local_inner_macros`; see
+/// <https://doc.rust-lang.org/edition-guide/rust-2018/macros/macro-changes.html#macros-using-local_inner_macros>.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _memoffset__compile_error {
+    ($($inner:tt)*) => {
+        compile_error! { $($inner)* }
+    }
+}
+
+/// Produces a range instance representing the sub-slice containing the specified member.
+///
+/// This macro provides 2 forms of differing functionalities.
+///
+/// The first form is identical to the appearance of the `offset_of!` macro.
+///
+/// ```ignore
+/// span_of!(Struct, member)
+/// ```
+///
+/// The second form of `span_of!` returns a sub-slice which starts at one field, and ends at another.
+/// The general pattern of this form is:
+///
+/// ```ignore
+/// // Exclusive
+/// span_of!(Struct, member_a .. member_b)
+/// // Inclusive
+/// span_of!(Struct, member_a ..= member_b)
+///
+/// // Open-ended ranges
+/// span_of!(Struct, .. end)
+/// span_of!(Struct, start ..)
+/// ```
+///
+/// *Note*:
+/// This macro uses recursion in order to resolve the range expressions, so there is a limit to
+/// the complexity of the expression.
+/// In order to raise the limit, the compiler's recursion limit should be lifted.
+///
+/// ## Examples
+/// ```
+/// use memoffset::span_of;
+///
+/// #[repr(C)]
+/// struct Florp {
+///     a: u32
+/// }
+///
+/// #[repr(C)]
+/// struct Blarg {
+///     x: [u32; 2],
+///     y: [u8; 56],
+///     z: Florp,
+///     egg: [[u8; 4]; 4]
+/// }
+///
+/// fn main() {
+///     assert_eq!(0..84,  span_of!(Blarg, ..));
+///     assert_eq!(0..8,   span_of!(Blarg, .. y));
+///     assert_eq!(0..64,  span_of!(Blarg, ..= y));
+///     assert_eq!(0..8,   span_of!(Blarg, x));
+///     assert_eq!(8..84,  span_of!(Blarg, y ..));
+///     assert_eq!(0..8,   span_of!(Blarg, x .. y));
+///     assert_eq!(0..64,  span_of!(Blarg, x ..= y));
+/// }
+/// ```
+#[macro_export(local_inner_macros)]
+macro_rules! span_of {
+    (@helper  $root:ident, [] ..=) => {
+        _memoffset__compile_error!("Expected a range, found '..='")
+    };
+    (@helper $root:ident, [] ..) => {
+        _memoffset__compile_error!("Expected a range, found '..'")
+    };
+    // No explicit begin for range.
+    (@helper $root:ident, $parent:path, [] ..) => {{
+        ($root as usize,
+         $root as usize + $crate::__priv::size_of_pointee($root))
+    }};
+    (@helper $root:ident, $parent:path, [] ..= $end:tt) => {{
+        let end = raw_field!($root, $parent, $end);
+        ($root as usize, end as usize + $crate::__priv::size_of_pointee(end))
+    }};
+    (@helper $root:ident, $parent:path, [] .. $end:tt) => {{
+        ($root as usize, raw_field!($root, $parent, $end) as usize)
+    }};
+    // Explicit begin and end for range.
+    (@helper $root:ident, $parent:path, # $begin:tt [] ..= $end:tt) => {{
+        let begin = raw_field!($root, $parent, $begin);
+        let end = raw_field!($root, $parent, $end);
+        (begin as usize, end as usize + $crate::__priv::size_of_pointee(end))
+    }};
+    (@helper $root:ident, $parent:path, # $begin:tt [] .. $end:tt) => {{
+        (raw_field!($root, $parent, $begin) as usize,
+         raw_field!($root, $parent, $end) as usize)
+    }};
+    // No explicit end for range.
+    (@helper $root:ident, $parent:path, # $begin:tt [] ..) => {{
+        (raw_field!($root, $parent, $begin) as usize,
+         $root as usize + $crate::__priv::size_of_pointee($root))
+    }};
+    (@helper $root:ident, $parent:path, # $begin:tt [] ..=) => {{
+        _memoffset__compile_error!(
+            "Found inclusive range to the end of a struct. Did you mean '..' instead of '..='?")
+    }};
+    // Just one field.
+    (@helper $root:ident, $parent:path, # $field:tt []) => {{
+        let field = raw_field!($root, $parent, $field);
+        (field as usize, field as usize + $crate::__priv::size_of_pointee(field))
+    }};
+    // Parsing.
+    (@helper $root:ident, $parent:path, $(# $begin:tt)+ [] $tt:tt $($rest:tt)*) => {{
+        span_of!(@helper $root, $parent, $(#$begin)* #$tt [] $($rest)*)
+    }};
+    (@helper $root:ident, $parent:path, [] $tt:tt $($rest:tt)*) => {{
+        span_of!(@helper $root, $parent, #$tt [] $($rest)*)
+    }};
+
+    // Entry point.
+    ($sty:path, $($exp:tt)+) => ({
+        // Get a base pointer.
+        _memoffset__let_base_ptr!(root, $sty);
+        let base = root as usize;
+        let (begin, end) = span_of!(@helper root, $sty, [] $($exp)*);
+        begin-base..end-base
+    });
+}
+
+#[cfg(test)]
+mod tests {
+    use core::mem;
+
+    #[test]
+    fn span_simple() {
+        #[repr(C)]
+        struct Foo {
+            a: u32,
+            b: [u8; 2],
+            c: i64,
+        }
+
+        assert_eq!(span_of!(Foo, a), 0..4);
+        assert_eq!(span_of!(Foo, b), 4..6);
+        assert_eq!(span_of!(Foo, c), 8..8 + 8);
+    }
+
+    #[test]
+    #[cfg_attr(miri, ignore)] // this creates unaligned references
+    fn span_simple_packed() {
+        #[repr(C, packed)]
+        struct Foo {
+            a: u32,
+            b: [u8; 2],
+            c: i64,
+        }
+
+        assert_eq!(span_of!(Foo, a), 0..4);
+        assert_eq!(span_of!(Foo, b), 4..6);
+        assert_eq!(span_of!(Foo, c), 6..6 + 8);
+    }
+
+    #[test]
+    fn span_forms() {
+        #[repr(C)]
+        struct Florp {
+            a: u32,
+        }
+
+        #[repr(C)]
+        struct Blarg {
+            x: u64,
+            y: [u8; 56],
+            z: Florp,
+            egg: [[u8; 4]; 5],
+        }
+
+        // Love me some brute force
+        assert_eq!(0..8, span_of!(Blarg, x));
+        assert_eq!(64..68, span_of!(Blarg, z));
+        assert_eq!(68..mem::size_of::<Blarg>(), span_of!(Blarg, egg));
+
+        assert_eq!(8..64, span_of!(Blarg, y..z));
+        assert_eq!(0..64, span_of!(Blarg, x..=y));
+    }
+
+    #[test]
+    fn ig_test() {
+        #[repr(C)]
+        struct Member {
+            foo: u32,
+        }
+
+        #[repr(C)]
+        struct Test {
+            x: u64,
+            y: [u8; 56],
+            z: Member,
+            egg: [[u8; 4]; 4],
+        }
+
+        assert_eq!(span_of!(Test, ..x), 0..0);
+        assert_eq!(span_of!(Test, ..=x), 0..8);
+        assert_eq!(span_of!(Test, ..y), 0..8);
+        assert_eq!(span_of!(Test, ..=y), 0..64);
+        assert_eq!(span_of!(Test, ..z), 0..64);
+        assert_eq!(span_of!(Test, ..=z), 0..68);
+        assert_eq!(span_of!(Test, ..egg), 0..68);
+        assert_eq!(span_of!(Test, ..=egg), 0..84);
+        assert_eq!(span_of!(Test, ..), 0..mem::size_of::<Test>());
+        assert_eq!(
+            span_of!(Test, x..),
+            offset_of!(Test, x)..mem::size_of::<Test>()
+        );
+        assert_eq!(
+            span_of!(Test, y..),
+            offset_of!(Test, y)..mem::size_of::<Test>()
+        );
+
+        assert_eq!(
+            span_of!(Test, z..),
+            offset_of!(Test, z)..mem::size_of::<Test>()
+        );
+        assert_eq!(
+            span_of!(Test, egg..),
+            offset_of!(Test, egg)..mem::size_of::<Test>()
+        );
+        assert_eq!(
+            span_of!(Test, x..y),
+            offset_of!(Test, x)..offset_of!(Test, y)
+        );
+        assert_eq!(
+            span_of!(Test, x..=y),
+            offset_of!(Test, x)..offset_of!(Test, y) + mem::size_of::<[u8; 56]>()
+        );
+    }
+}