Rust 1.87.0 complains about size-of@0.1.5 usage of "fastcall" on a Mac target

[lemvik]

Hi!

Overview

After updating to Rust toolchain version 1.87.0 we started getting the following complaint from the compiler:

warning: the following packages contain code that will be rejected by a future version of Rust: size-of v0.1.5

Apparently it is related to fastcall convention being used to specify foreign function - on a Mac it has no effect and was previously allowed, but now it's about to become an error.

This tracking issue seems related: rust-lang/rust#87678

Steps to reproduce

Create a new project, add size-of to it and try to build using stable-aarch64-apple-darwin toolchain.

[wangeguo]

I also encountered this issue.

[tdelabro]

Same here.
Is a fix coming?
Otherwise I think I will have to remove the support for SizeOf trait at some point

[Ukko-Ylijumala]

I fixed the immediate issue of compiler bailing out with this: Ukko-Ylijumala@c7e892a

I'm not sure if it's exactly right, but it gets the code to compile (on x86_64) and looks to be working.

edit: AI fetched me the list of valid conventions for arches beyond x86_64 so that part could be wrong, mind.