Re-exporting types, values, and/or macros with the same names can cause false-positives

[tonowak]

Steps to reproduce the bug with the above code

Clone clap, git checkout v3.2.0, cargo semver-checks check-release --baseline-rev=v3.1.18

Actual Behaviour

     Parsing clap v3.2.0 (current)
     Parsing clap v3.1.18 (baseline)
    Checking clap v3.1.18 -> v3.2.0 (minor change)
   Completed [   3.620s] 35 checks; 33 passed, 2 failed, 5 unnecessary

--- failure auto_trait_impl_removed: auto trait no longer implemented ---

Description:
A public type has stopped implementing one or more auto traits. This can break downstream code that depends on the traits being implemented.
        ref: https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits
       impl: https://github.com/obi1kenobi/cargo-semver-check/tree/v0.17.1/src/queries/auto_trait_impl_removed.ron

Failed in:
  type Arg is no longer UnwindSafe, in src/builder/arg.rs:61
  type Arg is no longer RefUnwindSafe, in src/builder/arg.rs:61
  type ArgMatches is no longer UnwindSafe, in src/parser/matches/arg_matches.rs:68
  type ArgMatches is no longer RefUnwindSafe, in src/parser/matches/arg_matches.rs:68
  type App is no longer UnwindSafe, in src/builder/command.rs:75
  type App is no longer RefUnwindSafe, in src/builder/command.rs:75
  type App is no longer UnwindSafe, in src/builder/command.rs:75
  type App is no longer RefUnwindSafe, in src/builder/command.rs:75
  type Values is no longer UnwindSafe, in src/parser/matches/arg_matches.rs:1466
  type Values is no longer RefUnwindSafe, in src/parser/matches/arg_matches.rs:1466
  type OsValues is no longer UnwindSafe, in src/parser/matches/arg_matches.rs:1548
  type OsValues is no longer RefUnwindSafe, in src/parser/matches/arg_matches.rs:1548

--- failure trait_missing: pub trait removed or renamed ---

Description:
A publicly-visible trait cannot be imported by its prior path. A `pub use` may have been removed, or the trait itself may have been renamed or removed entirely.
        ref: https://doc.rust-lang.org/cargo/reference/semver.html#item-remove
       impl: https://github.com/obi1kenobi/cargo-semver-check/tree/v0.17.1/src/queries/trait_missing.ron

Failed in:
  trait clap::ArgEnum, previously in file src/derive.rs:420
       Final [   3.735s] semver requires new major version: 2 major and 0 minor checks failed

Expected Behaviour

     Parsing clap v3.2.0 (current)
     Parsing clap v3.1.18 (baseline)
    Checking clap v3.1.18 -> v3.2.0 (minor change)
   Completed [   4.668s] 35 checks; 34 passed, 1 failed, 5 unnecessary

--- failure auto_trait_impl_removed: auto trait no longer implemented ---

Description:
A public type has stopped implementing one or more auto traits. This can break downstream code that depends on the traits being implemented.
        ref: https://doc.rust-lang.org/reference/special-types-and-traits.html#auto-traits
       impl: https://github.com/obi1kenobi/cargo-semver-check/tree/v0.17.1/src/queries/auto_trait_impl_removed.ron

Failed in:
  type OsValues is no longer UnwindSafe, in src/parser/matches/arg_matches.rs:1548
  type OsValues is no longer RefUnwindSafe, in src/parser/matches/arg_matches.rs:1548
  type Values is no longer UnwindSafe, in src/parser/matches/arg_matches.rs:1466
  type Values is no longer RefUnwindSafe, in src/parser/matches/arg_matches.rs:1466
  type App is no longer UnwindSafe, in src/builder/command.rs:75
  type App is no longer RefUnwindSafe, in src/builder/command.rs:75
  type App is no longer UnwindSafe, in src/builder/command.rs:75
  type App is no longer RefUnwindSafe, in src/builder/command.rs:75
  type Arg is no longer UnwindSafe, in src/builder/arg.rs:61
  type Arg is no longer RefUnwindSafe, in src/builder/arg.rs:61
  type ArgMatches is no longer UnwindSafe, in src/parser/matches/arg_matches.rs:68
  type ArgMatches is no longer RefUnwindSafe, in src/parser/matches/arg_matches.rs:68
       Final [   4.790s] semver requires new major version: 1 major and 0 minor checks failed

Generated System Information

Software version

cargo-semver-checks 0.17.1

Operating system

Linux 6.1.9-arch1-1

Command-line

/home/tonowak/.cargo/bin/cargo-semver-checks semver-checks --bugreport

cargo version

> cargo -V
cargo 1.67.0-beta.2 (f6e737b1e 2022-12-02)

Compile time information

• Profile: release
• Target triple: x86_64-unknown-linux-gnu
• Family: unix
• OS: linux
• Architecture: x86_64
• Pointer width: 64
• Endian: little
• CPU features: fxsr,sse,sse2
• Host: x86_64-unknown-linux-gnu

Build Configuration

No response

Additional Context

The false positive is present in stable, beta and nightly.

[obi1kenobi]

I'm seeing this on all of 1.67 (stable), 1.68 (current beta), and 1.69 (nightly). I'm worried that you aren't seeing it on your nightly. Can you run rustup upgrade and try stable/beta/nightly again?

[tonowak]

I've updated my Rust versions and now I have the issues on all three Rust releases. I've edited the description.

[obi1kenobi]

Good news: the mentioned trait is indeed missing but the missing name is behind a #[doc(hidden)], so it isn't a new issue.

Bad news: the error message did not exactly make this easy to figure out.

I'm going to leave aside the #[doc(hidden)] question which will require a more systematic solution, and use this opportunity to improve the error message.

Turns out this was actually caused by incomplete rustdoc JSON information in the case where more than one re-exported item happens to share the same name, which is allowed since values, types, and macros have their own namespaces. In clap v3.2.0, ArgEnum is both a trait and a derive macro for that trait, but the rustdoc JSON only lists the derive macro. cargo-semver-checks correctly reports that the trait is missing from the JSON file — but the problem is the JSON file, not the clap source code.

It is not related to #[doc(hidden)].

Underlying issue: rust-lang/rust#107677
Adapter test case: obi1kenobi/trustfall-rustdoc-adapter#72

[obi1kenobi]

The fix for the underlying issue in rustdoc was just merged, so this should make its way over to nightly Rust very soon.

[obi1kenobi]

The fix is available in Rust 1.69 beta (also in nightly) so it should make its way to stable in a few weeks.

If you are a user affected by this issue, the best workaround in the meantime is to run semver-checking on beta Rust by running rustup override set beta before the cargo semver-checks check-release command.

For posterity, Rust 1.68.1 stable and earlier still exhibit this problem, as you can see in this build log: https://github.com/obi1kenobi/trustfall-rustdoc-adapter/actions/runs/4504360060/jobs/7928735963

There's not much we can do in the meantime, so I'm going to close this issue.