Pre-release tags in package versions

[kokkonisd]

Description

I've noticed that, sadly, SemVer is not actually fully supported in local packages (I'm assuming this is also an issue with "published" packages, but I haven't published one so far so I'm not sure). Assume the following typst.toml:

[package]
name = "test"
version = "0.1.0-dev"
entrypoint = "src/lib.typ"

We then follow the instructions on this repo to install this test package locally, placing it in, e.g., $HOME/.local/share/typst/packages/local/test/0.1.0-dev/. We can also create a src/ directory with an empty lib.typ file inside it (as promised for the entrypoint), but it doesn't matter in this example.

Now, let's try to use this package in another file, called example.typ:

#import "@local/test:0.1.0-dev": *

When we try to compile it, we get the following error:

$ typst c example.typ
error: `0-dev` is not a valid patch version
  ┌─ example.typ:1:8
  │
1 │ #import "@local/test:0.1.0-dev": *
  │         ^^^^^^^^^^^^^^^^^^^^^^^

This is surprising, as 0-dev is in fact a valid patch version! More specifically, SemVer 2.0.0's grammar states that the "version core" (MAJOR.MINOR.PATCH) can be followed by a "pre-release" tag, such as -dev.

Is there any reason why only a subset of SemVer is supported?

[elegaanz]

The current implementation makes it easier to parse and reason about package versions, even if it is not technically compliant with the semver specification. We may implement pre-release tags in the future, but it is not a priority for now. Also, changing the version format would break the compiler (because it wouldn't be able to parse the package index anymore), so it needs to be done carefully the day we decide to implement it.

[Myriad-Dreamin]

cargo made some stupid mistakes when implementing pre-release suffixes, so typst should be careful to not
repeating the mistakes. It should be compatible with semver but be much more strict to make convenient uses.

• Pre-release version numbers rust-lang/cargo#2222