cranelift-object: Make sections read only by default

[afonso360]

This changes the default section type to be ReadOnlyDataWithRel instead of Data.

On COFF the CRT initializers do not run unless their section is read only. (See: rust-lang/rustc_codegen_cranelift#1249 (comment))

The new SectionKind makes these sections read only for COFF and MachO, but leaves it as Writable as required by ELF.

cc: @bjorn3

[cfallin]

The diff itself looks fine here; I'll trust that this section type is what is needed :-)

Regarding CI:

• Can you see if you can consolidate deps back to one version of object? There's probably another crate somewhere still using the old version.
• One of us will need to vet the diff for the object upgrade; I'll get to this in a bit if no one else does first!

[afonso360]

Can you see if you can consolidate deps back to one version of object? There's probably another crate somewhere still using the old version.

Did the best I could, we are now only duplicating the hashbrown crate. The old version is a dependency of indexmap which itself is a dependency of 3-4 other crates, and I figured this would be a good place to stop.

Also hashbrown has moved some of their API that we used behind a feature flag.

One of us will need to vet the diff for the object upgrade; I'll get to this in a bit if no one else does first!

👍, You also recently did a similar vet for object up to 0.30 in #5434 (comment) so we're just missing 0.30 -> 0.30.3.

[cfallin]

@afonso360 would you be willing to update this with an exemption for the hashbrown version duplication to the cargo-deny config (if the issue hasn't gone away with updates in the meantime)? Otherwise I think this PR is ready to go...

[afonso360]

I've rebased this and added the exception, but I think we still have the same issue with cargo vet of missing a few vet's similar to #5550.

[afonso360]

Rebased this on top of main, and that resolves pretty much all of our vet issues. With the exception of object 0.30.1 -> 0.30.3, that update is introduced in this PR since SectionKind::ReadOnlyDataWithRel didn't exist before.

[jameysharp]

Once #5827 merges you should be able to rebase this without any cargo-vet complaints. At that point, go ahead and merge!

[afonso360]

Thanks for unblocking this! 🎉

[afonso360]

The merge queue failure seems to have been sporadic, I retried the job and it passed. I'm going to retry the merge queue again.