Replacing an enum with a typedef is breaking and a hazard, but not semver-major

[obi1kenobi]

Replacing an enum with a typedef is a breaking change, due to the inability to glob-import via the typedef.

But not all breaking changes are major — so is this one major? Is it minor? Should it instead just be a warn level lint pointing out the hazard?

Playground link

fn main() {
    // Works
    // enum Foo {A, B}

    enum SecretFoo {
        A,
        B,
    }
    type Foo = SecretFoo;
    
    // Works fine
    let x = Foo::A;

    // Doesn't work
    use Foo::*;
    let y = A;
}

Example courtesy of @aDotInTheVoid.

[obi1kenobi]

It's not just glob imports that are problematic. Replacing the glob with a direct import of the variant (use Foo::A) doesn't work either.

[obi1kenobi]

I believe this is just a hazard, not breaking. I've laid out my reasoning here: https://predr.ag/blog/re-exporting-enum-with-type-alias-breaking-change-not-major/

[obi1kenobi]

This issue just happened in the time crate in v0.3.35: time-rs/time#675