Fix stack overflow in CoreDID PartialEq impl

[PhilippGackstatter]

Description of change

Fixes an infinite recursion when comparing CoreDIDs. The following example currently causes a stack overflow:

let example1 = CoreDID::parse("did:example:0x0").unwrap();
let example2 = CoreDID::parse("did:example:0x1").unwrap();
println!("{}", example1 == &example2);

The Rust compiler ends up effectively calling:

<CoreDID as PartialEq<&CoreDID>>::eq(&example1, &&example2)

which recurses infinitely. The implementation is:

impl PartialEq<&CoreDID> for CoreDID {
  fn eq(&self, other: &&CoreDID) -> bool {
    self == other
  }
}

Two options for fixing the situation: 1) Using *other or 2) removing the impl. We don't use this implementation anywhere, and since this impl has been around for 9 months without anyone running into the problem, there's a good chance no one is using it. Note that this is an additional implementation next to the derived PartialEq impl on CoreDID. So this PR removes this impl. However, if we don't want this to be a breaking change or think it's a convenient impl, we can also go with option 1.

Edit: CI is failing due to a known ICE: rust-lang/rust#99261

Links to any relevant issues

n/a

Type of change

Add an x to the boxes that are relevant to your changes.

• Bug fix (a non-breaking change which fixes an issue)
• Enhancement (a non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Fix

How the change has been tested

Ran the above example before and after the change.

Change checklist

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• I have followed the contribution guidelines for this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[cycraig]

Not sure why that PartialEq existed (my fault for adding it, just not sure why, apologies). It could have been from when unsafe was used to transmute transparent DID types but that's just a guess (probably not).

Thanks for fixing it! Fully agree to remove the impl, no loss of functionality since CoreDID still derives PartialEq.