offset_of! ecosystem testing #111839
Description
I'm filing this issue to get some testing of the offset_of macro, whose implementation has recently been merged in #106934 .
There is already widespread use of the offset_of macro in the ecosystem through an implementation supporting stable via the memoffset crate, whose version 0.9.0 supports the unstable_offset_of feature due to Gilnaa/memoffset#72. So for a lot of the users, testing out is as simple as updating memoffset and running the tests with the unstable_offset_of feature enabled. Thankfully, for testing one doesn't have to add that feature to Cargo.toml, creating a requirement on nightly, one can just add --features memoffset/unstable_offset_of and it will work.
The biggest reverse dependencies of memoffset are:
It would be good to go through this list, and:
- update the
memoffsetcrate to 0.9.0, ideally filing a PR (but not enablingunstable_offset_ofin Cargo.toml unless the project already requires nightly!) - run
cargo +nightly test --features memoffset/unstable_offset_oforcargo +nightly run --features memoffset/unstable_offset_ofetc, trying out the feature and seeing if something is broken, ideally also the--allparameter if it's a workspace - tell here about the experience
In addition of that, it is useful to get feedback from any project that uses the memoffset crate indirectly as a transitive dependency. For that, one also has to wait for the upgrade to 0.9.0 to go through the dependency chain and then one can add a direct (unused) dependency on memoffset to enable the feature, and test it out.
For example, field-offset has a large number of reverse dependencies that one could go through also. I have made a PR for rustc in #112298.
cc #106655 tracking issue
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#![feature(offset_of)]#106655[-]offset_of ecosystem testing[/-][+]`offset_of!` ecosystem testing[/+]est31 commentedon May 22, 2023
@rustbot label F-offset_of
est31 commentedon May 22, 2023
@rustbot label E-help-wanted
memoffsetto v0.9 crossbeam-rs/crossbeam#981memoffset0.9 Diggsey/rust-field-offset#24Merge #981
29 remaining items
DO NOT MERGE: Test with memoffset/unstable_offset_of feature
joshlf commentedon Oct 24, 2023
Confirmed for field-offset. Confirmed for pyo3 (there were trybuild failures, but I believe they're related to compiler version, not behavior changes).
Some of the remaining crates are difficult to test locally for one reason or another. I've put up do-not-merge PRs that enable memoffset's
unstable_offset_offeature so that CI can run on those PRs as a replacement for running the test suites locally.rust-vmm/vm-virtio#268(CI only tests on stable; I've requested a maintainer to run for us: rust-vmm/vm-virtio#269)ggez/ggez#1260
DO NOT MERGE: Test with memoffset/unstable_offset_of feature
DO NOT MERGE: Test with memoffset/unstable_offset_of feature
offset_of!macro rust-vmm/vm-virtio#269joshlf commentedon Oct 24, 2023
Confirmed for virtio-queue.
joshlf commentedon Oct 25, 2023
@est31 Are we hoping to get to 100% coverage here, or is 14/16 good enough? (For the remaining 2, we haven't found issues, we've just run into unrelated problems running the test or getting the feature merged.)
est31 commentedon Oct 28, 2023
It's not a precise science, my main goal for the list was to give a starting point. I think we can close this particular issue which was mostly to get things started, as projects often use stable only and are afraid to use nightly features (and indeed there is discussions to maybe change the syntax of
offset_of). Of course, even if this issue is closed, further testing will always be encouraged.Thanks ❤️ @joshlf for your help, and thanks @ojeda and everyone else for confirming that it works for their use cases.
ojeda commentedon Oct 28, 2023
My pleasure!
Update memoffset to 0.9.0
Update memoffset to 0.9.0