rust: remove offset_of replacement

Reviewed-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

4 files changed, 8 insertions, 180 deletions

diff --git a/rust/qemu-api/src/lib.rs b/rust/qemu-api/src/lib.rs
index c3641e8..90c1963 100644
--- a/rust/qemu-api/src/lib.rs
+++ b/rust/qemu-api/src/lib.rs
@@ -23,7 +23,6 @@ pub mod errno;
 pub mod irq;
 pub mod memory;
 pub mod module;
-pub mod offset_of;
 pub mod qdev;
 pub mod qom;
 pub mod sysbus;
@@ -165,6 +164,3 @@ unsafe impl GlobalAlloc for QemuAllocator {
         }
     }
 }
-
-#[cfg(has_offset_of)]
-pub use core::mem::offset_of;
diff --git a/rust/qemu-api/src/offset_of.rs b/rust/qemu-api/src/offset_of.rs
deleted file mode 100644
index 373229b..0000000
--- a/rust/qemu-api/src/offset_of.rs
+++ /dev/null
@@ -1,168 +0,0 @@
-// SPDX-License-Identifier: MIT
-
-#![doc(hidden)]
-//! This module provides macros that emulate the functionality of
-//! `core::mem::offset_of` on older versions of Rust.
-//!
-//! Documentation is hidden because it only exposes macros, which
-//! are exported directly from `qemu_api`.
-
-/// This macro provides the same functionality as `core::mem::offset_of`,
-/// except that only one level of field access is supported.  The declaration
-/// of the struct must be wrapped with `with_offsets! { }`.
-///
-/// It is needed because `offset_of!` was only stabilized in Rust 1.77.
-#[cfg(not(has_offset_of))]
-#[macro_export]
-macro_rules! offset_of {
-    ($Container:ty, $field:ident) => {
-        <$Container>::OFFSET_TO__.$field
-    };
-}
-
-/// A wrapper for struct declarations, that allows using `offset_of!` in
-/// versions of Rust prior to 1.77
-#[macro_export]
-macro_rules! with_offsets {
-    // This method to generate field offset constants comes from:
-    //
-    //     https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=10a22a9b8393abd7b541d8fc844bc0df
-    //
-    // used under MIT license with permission of Yandros aka Daniel Henry-Mantilla
-    (
-        $(#[$struct_meta:meta])*
-        $struct_vis:vis
-        struct $StructName:ident {
-            $(
-                $(#[$field_meta:meta])*
-                $field_vis:vis
-                $field_name:ident : $field_ty:ty
-            ),*
-            $(,)?
-        }
-    ) => (
-        #[cfg(not(has_offset_of))]
-        const _: () = {
-            struct StructOffsetsHelper<T>(std::marker::PhantomData<T>);
-            const END_OF_PREV_FIELD: usize = 0;
-
-            // populate StructOffsetsHelper<T> with associated consts,
-            // one for each field
-            $crate::with_offsets! {
-                @struct $StructName
-                @names [ $($field_name)* ]
-                @tys [ $($field_ty ,)*]
-            }
-
-            // now turn StructOffsetsHelper<T>'s consts into a single struct,
-            // applying field visibility.  This provides better error messages
-            // than if offset_of! used StructOffsetsHelper::<T> directly.
-            pub
-            struct StructOffsets {
-                $(
-                    $field_vis
-                    $field_name: usize,
-                )*
-            }
-            impl $StructName {
-                pub
-                const OFFSET_TO__: StructOffsets = StructOffsets {
-                    $(
-                        $field_name: StructOffsetsHelper::<$StructName>::$field_name,
-                    )*
-                };
-            }
-        };
-    );
-
-    (
-        @struct $StructName:ident
-        @names []
-        @tys []
-    ) => ();
-
-    (
-        @struct $StructName:ident
-        @names [$field_name:ident $($other_names:tt)*]
-        @tys [$field_ty:ty , $($other_tys:tt)*]
-    ) => (
-        #[allow(non_local_definitions)]
-        #[allow(clippy::modulo_one)]
-        impl StructOffsetsHelper<$StructName> {
-            #[allow(nonstandard_style)]
-            const $field_name: usize = {
-                const ALIGN: usize = std::mem::align_of::<$field_ty>();
-                const TRAIL: usize = END_OF_PREV_FIELD % ALIGN;
-                END_OF_PREV_FIELD + (if TRAIL == 0 { 0usize } else { ALIGN - TRAIL })
-            };
-        }
-        const _: () = {
-            const END_OF_PREV_FIELD: usize =
-                StructOffsetsHelper::<$StructName>::$field_name +
-                std::mem::size_of::<$field_ty>()
-            ;
-            $crate::with_offsets! {
-                @struct $StructName
-                @names [$($other_names)*]
-                @tys [$($other_tys)*]
-            }
-        };
-    );
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::offset_of;
-
-    #[repr(C)]
-    struct Foo {
-        a: u16,
-        b: u32,
-        c: u64,
-        d: u16,
-    }
-
-    #[repr(C)]
-    struct Bar {
-        pub a: u16,
-        pub b: u64,
-        c: Foo,
-        d: u64,
-    }
-
-    crate::with_offsets! {
-        #[repr(C)]
-        struct Bar {
-            pub a: u16,
-            pub b: u64,
-            c: Foo,
-            d: u64,
-        }
-    }
-
-    #[repr(C)]
-    pub struct Baz {
-        b: u32,
-        a: u8,
-    }
-    crate::with_offsets! {
-        #[repr(C)]
-        pub struct Baz {
-            b: u32,
-            a: u8,
-        }
-    }
-
-    #[test]
-    fn test_offset_of() {
-        const OFFSET_TO_C: usize = offset_of!(Bar, c);
-
-        assert_eq!(offset_of!(Bar, a), 0);
-        assert_eq!(offset_of!(Bar, b), 8);
-        assert_eq!(OFFSET_TO_C, 16);
-        assert_eq!(offset_of!(Bar, d), 40);
-
-        assert_eq!(offset_of!(Baz, b), 0);
-        assert_eq!(offset_of!(Baz, a), 4);
-    }
-}
diff --git a/rust/qemu-api/src/qdev.rs b/rust/qemu-api/src/qdev.rs
index 17c7fec..1279d7a 100644
--- a/rust/qemu-api/src/qdev.rs
+++ b/rust/qemu-api/src/qdev.rs
@@ -190,7 +190,7 @@ macro_rules! define_property {
             // use associated function syntax for type checking
             name: ::std::ffi::CStr::as_ptr($name),
             info: $prop,
-            offset: $crate::offset_of!($state, $field) as isize,
+            offset: ::std::mem::offset_of!($state, $field) as isize,
             bitnr: $bitnr,
             set_default: true,
             defval: $crate::bindings::Property__bindgen_ty_1 { u: $defval as u64 },
@@ -202,7 +202,7 @@ macro_rules! define_property {
             // use associated function syntax for type checking
             name: ::std::ffi::CStr::as_ptr($name),
             info: $prop,
-            offset: $crate::offset_of!($state, $field) as isize,
+            offset: ::std::mem::offset_of!($state, $field) as isize,
             set_default: true,
             defval: $crate::bindings::Property__bindgen_ty_1 { u: $defval as u64 },
             ..$crate::zeroable::Zeroable::ZERO
@@ -213,7 +213,7 @@ macro_rules! define_property {
             // use associated function syntax for type checking
             name: ::std::ffi::CStr::as_ptr($name),
             info: $prop,
-            offset: $crate::offset_of!($state, $field) as isize,
+            offset: ::std::mem::offset_of!($state, $field) as isize,
             set_default: false,
             ..$crate::zeroable::Zeroable::ZERO
         }
diff --git a/rust/qemu-api/src/vmstate.rs b/rust/qemu-api/src/vmstate.rs
index c0f29f7..205f35a 100644
--- a/rust/qemu-api/src/vmstate.rs
+++ b/rust/qemu-api/src/vmstate.rs
@@ -205,8 +205,8 @@ macro_rules! vmstate_of {
             name: ::core::concat!(::core::stringify!($field_name), "\0")
                 .as_bytes()
                 .as_ptr() as *const ::std::os::raw::c_char,
-            offset: $crate::offset_of!($struct_name, $field_name),
-            $(num_offset: $crate::offset_of!($struct_name, $num),)?
+            offset: ::std::mem::offset_of!($struct_name, $field_name),
+            $(num_offset: ::std::mem::offset_of!($struct_name, $num),)?
             $(field_exists: $crate::vmstate_exist_fn!($struct_name, $test_fn),)?
             // The calls to `call_func_with_field!` are the magic that
             // computes most of the VMStateField from the type of the field.
@@ -483,10 +483,10 @@ macro_rules! vmstate_struct {
             name: ::core::concat!(::core::stringify!($field_name), "\0")
                 .as_bytes()
                 .as_ptr() as *const ::std::os::raw::c_char,
-            $(num_offset: $crate::offset_of!($struct_name, $num),)?
+            $(num_offset: ::std::mem::offset_of!($struct_name, $num),)?
             offset: {
                 $crate::assert_field_type!($struct_name, $field_name, $type $(, num = $num)?);
-                $crate::offset_of!($struct_name, $field_name)
+                ::std::mem::offset_of!($struct_name, $field_name)
             },
             size: ::core::mem::size_of::<$type>(),
             flags: $crate::bindings::VMStateFlags::VMS_STRUCT,
@@ -518,7 +518,7 @@ macro_rules! vmstate_clock {
                     $field_name,
                     $crate::qom::Owned<$crate::qdev::Clock> $(, num = $num)?
                 );
-                $crate::offset_of!($struct_name, $field_name)
+                ::std::mem::offset_of!($struct_name, $field_name)
             },
             size: ::core::mem::size_of::<*const $crate::qdev::Clock>(),
             flags: $crate::bindings::VMStateFlags(