Type aliases of types defined outside the current crate are not checked

[jrmuizel]

Steps to reproduce the bug with the above code

Run cargo semver-checks check-release in the core-foundation-sys directory of https://github.com/servo/core-foundation-rs @ eb00adae0c6d3694dccc54b195132c2929ac8c96

Actual Behaviour

No changes detected

Expected Behaviour

semver-checks fails to detect that UniChar has moved from string:: to base::

Generated System Information

Software version

cargo-semver-checks 0.21.0

Operating system

Mac OS X 10.15.6 (Darwin 19.6.0)

Command-line

/Users/jrmuizel/.cargo/bin/cargo-semver-checks semver-checks --bugreport

cargo version

> cargo -V
cargo 1.70.0 (ec8a8a0ca 2023-04-25)

Compile time information

• Profile: release
• Target triple: x86_64-apple-darwin
• Family: unix
• OS: macos
• Architecture: x86_64
• Pointer width: 64
• Endian: little
• CPU features: fxsr,sse,sse2,sse3,ssse3
• Host: x86_64-apple-darwin

Build Configuration

No response

Additional Context

No response

[jrmuizel]

Actually, semver-checks will detect

  --- failure function_missing: pub fn removed or renamed ---

Description:
A publicly-visible function cannot be imported by its prior path. A `pub use` may have been removed, or the function 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/v0.21.0/src/lints/function_missing.ron

Failed in:
  function core_foundation_sys::url::CFURLStopAccessingSecurityScopedResource, previously in file /Users/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/core-foundation-sys-0.8.4/src/url.rs:162
  function core_foundation_sys::url::CFURLStartAccessingSecurityScopedResource, previously in file /Users/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/core-foundation-sys-0.8.4/src/url.rs:161

but not the moved type mentioned above.

[jrmuizel]

If you use cf25b7d943624947ff027b38f75ce0a451b01eb0 instead it now shows no changes detected.

[obi1kenobi]

Thanks for the report.

This is a known issue, caused in part by the same limitation that also causes #355: cargo-semver-checks today cannot see or analyze types defined outside the crate being scanned. UniChar is defined as:

use std::os::raw::{c_uint, c_void, c_int, c_short, c_uchar, c_ushort};
// ...
pub type UniChar = c_ushort;

and c_ushort is an external type.

The limitation is due to the fact that external types' definitions are not part of the rustdoc JSON file of the scanned crate. There is currently no good way to connect data in multiple rustdoc JSON files together.

The rustdoc team is aware of this limitation and is interested in resolving it; I've stayed in touch with them on this.

Sorry I don't have a better answer!

[jrmuizel]

Is there an issue tracking the rustdoc problem?

[obi1kenobi]

This is the closest thing to a single tracking issue I could find: rust-lang/compiler-team#635

That's a prerequisite rustc change after which rustdoc JSON will probably tweak the format in some way that resolves the problems in this link, which is also mentioned in the issue.

[jrmuizel]

We ended up getting burnt with this with the release of core-foundation-sys 0.8.5. servo/core-foundation-rs#619

a pub use CFIndex was remove in servo/core-foundation-rs@6d00383 which broke semver and was not detected.