Re: [PATCH RFC 2/3] rust: implement a test balloon via the "varint" subsystem

From: Eli Schwartz <eschwartz@gentoo.org>
Date: Sep 5, 2025, 13:39 UTC
Message-ID: <033d35f5-6158-4402-b7f4-aaf525a3e64d@gentoo.org>
In-Reply-To: <aLqXHYb2jZpCKzp7@pks.im>

On 9/5/25 3:54 AM, Patrick Steinhardt wrote:

> On Thu, Sep 04, 2025 at 10:00:45PM -0400, Eli Schwartz wrote:

Show 13 quoted lines

>> If the rust code is defined as a crate, meson can auto-import that crate
>> via parsing Cargo.toml, so perhaps this can simply be done by creating a
>>
>> [lib]
>> crate-type = 'cdylib'
>>
>> and... importing it as a meson subproject. You'd be able to build it
>> with cargo build, if you really want to (and the Makefile may have to)
>> but Meson would not be limited to this.
> 
> That sounds like a sensible thing to do. Just to clarify, this doesn't
> need the experimental Cargo wraps, right? Is there any documentation for
> how to set this up?

Experimental cargo wraps are new since 1.3.0

https://mesonbuild.com/Release-notes-for-1-3-0.html#automatic-fallback-to-cmake-and-cargo-subproject https://mesonbuild.com/Wrap-dependency-system-manual.html#cargo-wraps

It operates by synthesizing a virtual `meson.build` file for you via translation of ordinary Cargo.toml. A copy of the synthesized file is written out to ${build_dir}/subprojects/foobar-1-rs/ (or whatever the subproject is named), so you can actually see what a manually written meson.build would look like.

And e.g. tweak it a bit. (Since it's a virtual file, it always writes `meson_version : '>= currentver'` to avoid ever triggering "feature new" warnings, and also stubs out `rust_dependency_map : {}`, but you can delete both.)

-- 
Eli Schwartz