| commit | 01ff0c6d2ee6d0f83edefafd0bd9c019c5fff5af | [log] [tgz] |
|---|---|---|
| author | Joel Galenson <jgalenson@google.com> | Tue Apr 27 14:35:54 2021 -0700 |
| committer | Joel Galenson <jgalenson@google.com> | Tue Apr 27 14:35:54 2021 -0700 |
| tree | a7d702e71f38ae1597839c01ccca8820999c02e9 | |
| parent | 4ba1537d75289a0f796ebf9b3ab44233804455df [diff] |
Generate apex_available from c2a instead of a patch Test: Run c2a Test: Build Change-Id: If0ced6184d7b16e19a874d13e0996ca9e42a5ab3
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.