Selecting prerelease versions doesn't work

[steveklabnik]

This test fails:

    #[test]
    pub fn test_pre() {
        let r = req("2.1.1-really.0");
        assert_match(&r, &["2.1.1-really.0"]);
    }

Discovered in rust-lang/cargo#2337

[steveklabnik]

Here's the core of it:

[AlphaNumeric("really"), AlphaNumeric("0")] == [AlphaNumeric("really"), Numeric(0)]

these are not considered equal for some reason

[steveklabnik]

So the root of the issue is multiple pre sections. With just -really, this works.

[steveklabnik]

Hrm, so https://play.rust-lang.org/?gist=f399089d777f3fc4effd&version=stable

#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
pub enum Identifier {
    /// An identifier that's solely numbers.
    Numeric(u64),
    /// An identifier with letters and numbers.
    AlphaNumeric(String)
}

I am confused as to how these two differ. We only use derive for {Partial,}Eq, so...

[steveklabnik]

Using the same definitions also works: https://play.rust-lang.org/?gist=cffbc41f771a38132c79&version=stable

ugh.

[steveklabnik]

OH: AlphaNumeric("0") vs Numeric(0)

Somehow, these two versions are being parsed differently. That's the problem.

[steveklabnik]

Adjusting the test:

        let v1 = VersionReq::parse("2.1.1-really.0").unwrap();
        let v2 = Version::parse("2.1.1-really.0").unwrap();
        println!("v1: {:?}", v1);
        println!("v2: {:?}", v2);

gives

v1: VersionReq { predicates: [Predicate { op: Compatible, major: 2, minor: Some(1), patch: Some(1), pre: [AlphaNumeric("really"), AlphaNumeric("0")] }] }
v2: Version { major: 2, minor: 1, patch: 1, pre: [AlphaNumeric("really"), Numeric(0)], build: [] }

So, it's that VersionReq parsing has a bug: it thinks that 0 is an AlphaNumeric when it should be a Numeric.

If only I had done that nom port already, I bet this wouldn't have happened :(

[steveklabnik]

PR submitted