Update TEST_MAPPING am: abfcb00917 am: 94cd43db7c am: 8000561bc6 Original change: https://android-review.googlesource.com/c/platform/external/rust/crates/memoffset/+/2411834 Change-Id: I3ded14e77f7f27e6fe47b830b31b1eb90cc41929 Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com> 
tree: a6463c28044e1541d12ab020ce4751fbb23fbc72
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  4. .cargo_vcs_info.json
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  6. Android.bp
  7. build.rs
  8. Cargo.toml
  9. Cargo.toml.orig
  10. cargo2android.json
  11. LICENSE
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  14. OWNERS
  15. README.md
  16. TEST_MAPPING
README.md

memoffset

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.

Usage

Add the following dependency to your Cargo.toml:

[dependencies] memoffset = "0.7" 

These versions will compile fine with rustc versions greater or equal to 1.19.

Examples

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); } 

Feature flags

Usage in constants

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 = "0.7" features = ["unstable_const"] 

Your crate root: (lib.rs/main.rs)

#![feature(const_ptr_offset_from, const_refs_to_cell)]