| commit | c9e1025196b802e60860ff6082cb78f7edb0aa9b | [log] [tgz] |
|---|---|---|
| author | Joel Galenson <jgalenson@google.com> | Wed Apr 28 22:10:47 2021 +0000 |
| committer | Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> | Wed Apr 28 22:10:47 2021 +0000 |
| tree | a7d702e71f38ae1597839c01ccca8820999c02e9 | |
| parent | 301ddc0487a5a72af364e8c4e93f474e8910d6d1 [diff] | |
| parent | ab3823c0e415fe8ef1afca8079646693efa206fc [diff] |
Generate apex_available from c2a instead of a patch am: 01ff0c6d2e am: 0a44958a3e am: ab3823c0e4 Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/memoffset/+/1688983 Change-Id: Ic9fc94c8593a98f90982853628638cb634ed4a6b
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.
Add the following lines at the top of your main.rs or lib.rs files.
#[macro_use] extern crate memoffset;
#[macro_use] extern crate memoffset; #[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(ptr_offset_from, const_ptr_offset_from, const_maybe_uninit_as_ptr, const_raw_ptr_deref)]
If you intend to use offset_of! inside a const fn, also add the const_fn compiler feature.