report the varargs_without_pattern lint in deps

[folkertdev]

tracking issue: #44930

After discussion in rust-lang/reference#2177 (comment).

Based on #143619 (comment) there was only one actual impacted crate https://crates.io/crates/binrw. The issue was fixed in jam1garner/binrw#342, and has since been released jam1garner/binrw#342 (comment).

Hence we may as well report this loudly.

r? @ghost

[joshtriplett]

When we move FCWs to warn in deps, we typically change them to deny-by-default as well. Could you please make that change too?

[joshtriplett]

@rfcbot merge lang

[rust-rfcbot]

Team member @joshtriplett has proposed to merge this. The next step is review by the rest of the tagged team members:

• @joshtriplett
• @nikomatsakis
• @scottmcm
• @tmandry
• @traviscross

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

cc @rust-lang/lang-advisors: FCP proposed for lang, please feel free to register concerns.
See this document for info about what commands tagged team members can give me.

[traviscross]

@rfcbot reviewed

(Inclusive of changing this to deny-by-default.)

[rust-rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[folkertdev]

I'm confused by that failure, there are 3 failing tests which is weird given the diff

failures:
    compiler/rustc_lint_defs/src/builtin.rs - builtin::FORBIDDEN_LINT_GROUPS (line 166)
    compiler/rustc_lint_defs/src/builtin.rs - builtin::VARARGS_WITHOUT_PATTERN (line 5559)
    compiler/rustc_lint_defs/src/builtin.rs - builtin::WARNINGS (line 1068)

Also locally the doc tests (which I believe is what these are) work fine when I run ./x test compiler/rustc_lint_defs --doc.

[ehuss]

Also locally the doc tests (which I believe is what these are) work fine when I run ./x test compiler/rustc_lint_defs --doc.

You need --stage 2 to reproduce.

The problem is a bit complicated. What happens is that rustdoc combines doctests into a single crate. When it fails to build that crate, it then falls back to the "unmerged" mode. With varargs_without_pattern being changed to Deny, the merged doctests no longer compile because fn foo(...) is now an error by default.

The example needs to be marked with ,compile_fail. I would also double-check that everything continues to work when testing with both stage1 and stage2, but I think that should be sufficient.

[folkertdev]

Thanks, that's very helpful. With that change stage 2 works but now stage 1 complains that compilation was successful even though the code block is marked as compile_fail. I guess/hope that just doesn't get tested in CI?

[ehuss]

Unfortunately stage1 is tested in CI (see here).

You can probably add something like this to make it fail on both:

# #![deny(varargs_without_pattern)]

add that towards the top of the example.