Add semantic versioning support to livecheck

[emcrisostomo (Enrico Maria Crisostomo)]

Today I noticed the following while working on a port update:

$ port livecheck devel/mongo-tools
mongo-tools seems to have been updated (port version: 3.6.0, new version: 3.6.0-rc8)

The devel/mongo-tools port uses the default livecheck settings set by the github port group.

I'm aware that version numbers are tricky to sort, and that many different versioning schemes are used, so there are no silver bullets. But since ​semantic versioning is widely used nowadays, perhaps we could kill many birds with a stone and avoid port maintainers to come up with custom regexes. The databases/mongo port, for example, uses the same versioning scheme used by devel/mongo-tools, and it overcomes this problem using a custom regex that drops the -* and only captures the dot-separated numerical part of the version number).

Implementing sorting of version numbers adhering to semver isn't complicated. Actually, I could contribute ​code to do it.

[ryandesign (Ryan Carsten Schmidt)]

Generally I like the idea of making our version comparisons more accurate. But note that livecheck uses the vercmp procedure, so any changes you make there will affect not only livecheck but also portfiles that use vercmp, and probably even the computations of port outdated. This might change the criteria portfile authors use when deciding whether to increase the epoch. So these changes certainly need to be done with great care and forethought, and communication with portfile authors (i.e. documentation) about the changed epoch requirements.

[ryandesign (Ryan Carsten Schmidt)]

Replying to emcrisostomo:

Actually, I could contribute ​code to do it.

That code says it is licensed under GPL-3+. I don't think we would be able to accept code under that license into MacPorts base, which is licensed BSD. If you wrote that code, you could presumably offer to license it to us under BSD if you wanted to.

[emcrisostomo (Enrico Maria Crisostomo)]

I will certainly be happy to license any code of mine under BSD anyway :) Thanks for your feedback, Ryan. I will dedicate some time to this during the weekend.