| commit | f9e82b0f07dd35ea2d9ae3bac17f4bed58ae6f30 | [log] [tgz] |
|---|---|---|
| author | Android Build Coastguard Worker <[email protected]> | Thu Apr 28 16:01:06 2022 +0000 |
| committer | Android Build Coastguard Worker <[email protected]> | Thu Apr 28 16:01:06 2022 +0000 |
| tree | 07eb299a12f6f2438012ce9047c89b2b095f915d | |
| parent | 3a1693a425d4486c0343007fb3da0e69e918bd69 [diff] | |
| parent | df849691f3074c6e5086ef022f2e6c808ff00407 [diff] |
Snap for 8512216 from df849691f3074c6e5086ef022f2e6c808ff00407 to tm-frc-resolv-release Change-Id: I30f089544fafa08415820bf86e5076595c5b3a0a
C-Like offset_of functionality for Rust structs.
Introduces the following macros:
offset_of! for obtaining the offset of a member of a struct.offset_of_tuple! for obtaining the offset of a member of a tuple. (Requires Rust 1.20+)span_of! for obtaining the range that a field, or fields, span.memoffset works under no_std environments.
Add the following dependency to your Cargo.toml:
[dependencies] memoffset = "0.6"
These versions will compile fine with rustc versions greater or equal to 1.19.
use memoffset::{offset_of, span_of}; #[repr(C, packed)] struct Foo { a: u32, b: u32, c: [u8; 5], d: u32, } fn main() { assert_eq!(offset_of!(Foo, b), 4); assert_eq!(offset_of!(Foo, d), 4+4+5); assert_eq!(span_of!(Foo, a), 0..4); assert_eq!(span_of!(Foo, a .. c), 0..8); assert_eq!(span_of!(Foo, a ..= c), 0..13); assert_eq!(span_of!(Foo, ..= d), 0..17); assert_eq!(span_of!(Foo, b ..), 4..17); }
memoffset has experimental support for compile-time offset_of! on a nightly compiler.
In order to use it, you must enable the unstable_const crate feature and several compiler features.
Cargo.toml:
[dependencies.memoffset] version = "0.6" features = ["unstable_const"]
Your crate root: (lib.rs/main.rs)
#![feature(const_ptr_offset_from, const_refs_to_cell)]