Julia prerelease tags are parsed as lexical strings, potentially causing ordering issues

[MilesCranmer]

Julia’s current prerelease tags (-beta1, -rc1, etc.) don't utilize the structured prerelease fields of VersionNumber. Instead of, e.g., -beta1, it should really be -beta.1.

Here is what gets stored inside the VersionNumber struct for 1.12.0-beta4, compared to -beta.4:

julia> VERSION |> dump
VersionNumber
  major: UInt32 0x00000001
  minor: UInt32 0x0000000c
  patch: UInt32 0x00000000
  prerelease: Tuple{String}
    1: String "beta4"
  build: Tuple{} ()

julia> v"1.12.0-beta.4" |> dump
VersionNumber
  major: UInt32 0x00000001
  minor: UInt32 0x0000000c
  patch: UInt32 0x00000000
  prerelease: Tuple{String, UInt64}
    1: String "beta"
    2: UInt64 0x0000000000000004
  build: Tuple{} ()

This means that prerelease versions are ordered lexically as strings, causing unintuitive ordering once double-digit suffixes appear:

julia> v"1.12.0-beta10" > v"1.12.0-beta2"
false

In contrast, using Tuple{String,UInt64} format avoids this issue:

julia> v"1.12.0-beta.10" > v"1.12.0-beta.2"
true

Thanks to @giordano's post here for explaining this subtlety: https://discourse.julialang.org/t/can-we-have-pre-release-versions-in-the-registry-v2/129887/2?u=milescranmer

[StefanKarpinski]

Are you suggesting a change to the parsing of VersionNumber or a change to the prerelease naming convention?

[MilesCranmer]

I don't have strong preferences for any particular solution

[giordano]

I'd suggest making the versioning convention consistent with VersionNumber parsing, and SemVer specification (which VersionNumber implements)