How do I use cfg to set different attributes on different target architectures?

Question

I have a struct which must be 16-byte aligned when targeting wasm.

How can I do this?

So for instance, I want to have this struct on wasm:

#[cfg(target_arch = "wasm32")] <- not sure about this
#[repr(c, align(16))]
struct Foo {...}

And this on all other architectures:

#[cfg(target_arch = "wasm32")] <- not sure about this
#[repr(c)]
struct Foo {...}

Is this possible to achieve with cfg? If so how?

Like this? https://stackoverflow.com/questions/42551113/is-it-possible-to-conditionally-enable-an-attribute-like-derive — kelsny, Oct 24 '22 at 19:58
More like this: https://doc.rust-lang.org/rust-by-example/attribute/cfg.html — Finomnis, Oct 24 '22 at 19:59

kelsny · Accepted Answer · 2022-10-24T20:19:13.467

2

Looks like its possible with cfg_attr:

#[cfg_attr(not(target_arch = "wasm32"), repr(C))]
#[cfg_attr(target_arch = "wasm32", repr(C, align(16)))]
struct Foo { ... }

edited Oct 24 '22 at 20:19

answered Oct 24 '22 at 20:04

kelsny

1 Answers1