[swift]: add support for dev snapshots and add 6.1

[jamieQ]

• adds a new 'dev-snapshot' nightly config entry
• configures this to output these dev compilers to a swift-dev-snapshot directory
• sets the current target to fetch Swift 6.1 dev snapshots. this value is expected to need to be updated when new future releases are cut

[jamieQ]

question for the maintainers: Swift typically has ~2 or so active pre-release branches per year. these generally are built with about the same frequency as the nightlies, but once a new release branch is cut, updated builds for old ones will cease (presumably).

so i'm wondering – is install_always appropriate here? i didn't entirely chase down the logic that it entails... but i guess the concern would be if the development snapshot version here becomes out of date (since it will require manual updating by someone currently), it might end up wasting bandwidth.

[mattgodbolt]

Hi @jamieQ - thanks for the question. install_always does indeed force it to install every time without checking.

For other nightlies we check a dated directory and so only install at most once a day, but that's special cased for the installer types that are "nightly" in nature. I think we can start with install_always and then work from there though if it becomes a problem.

[mattgodbolt]

This should be in the if: nightly section though, else it really will install every time anyone tries to install anything as opposed to our specific "nightly" install. In fact it looks like almost everything can be shared with the nightly section instead of copy pasting it?

[mattgodbolt]

I think (for example) you could just add - '6.1' to the targets: of the nightly block below, though it looks like this is a different ubuntu version? Should we update the nightly to be 2204 too?

(to test a local install you'd need to use:
ce_install --enable nightly install swift
or similar)

[jamieQ]

@mattgodbolt thanks for the feedback!

I think (for example) you could just add - '6.1' to the targets: of the nightly block below

from what i can tell, the URL is slightly different for the two flavors of dev builds. what i was trying to accomplish was to leave the existing nightly as-is (it fetches the main branch snapshot), and add a new one that can be periodically updated to use the next planned release version dev branch (version 6.1 as of now). here's an updated config that seems like it accomplishes this with a bit less duplication:

    nightly:
      if: nightly
      type: restQueryTarballs
      install_always: true
      toolchain: development
      url: https://download.swift.org/{toolchain}/ubuntu2004/latest-build.yml
      query: |
        'https://download.swift.org/{toolchain}/ubuntu2004' \
        + '/' + document['dir'] \
        + '/' + document['download']
      targets:
        - nightly
      dev-snapshot:
        dir: swift-dev-snapshot
        toolchain: swift-{name}-branch
        targets:
          - '6.1'

does this look okay to you? i must admit i don't quite understand how the config structure and substitutions work so i apologize if this is a bit naive.

it looks like this is a different ubuntu version? Should we update the nightly to be 2204 too?

this was an oversight on my part – i didn't intend to diverge from what was already here. as a slight aside: i am not particularly familiar with the Swift on Linux ecosystem – is there a reason to prefer the newer ubuntu versions?

[jamieQ]

i've optimistically pushed an update with changes along these lines. do let me know if there's anything else that seems off with this new config entry!