Nopos-warn in vulpix & Move warn tests form tests/neg to tests/warn: Batch 1

[szymon-rd]

Adds functionality to vulpix that allows putting nopos-warns in comments & First batch of tests moved from tests/neg to tests/warn.
PR 2/5 (merge consecutively, per Nicolas' suggestion

Split up version of #18829

[nicolasstucki]

@szymon-rd you should not create branches on the dotty repo. We are executing all tests twice on this PR (push/pull). That is one of the reasons why we use the dotty-staging repo.

[nicolasstucki]

Otherwise LGTM

[nicolasstucki]

tests/neg-deep-subtype/i3324.scala should be removed.

[nicolasstucki]

For files where git cannot track the change, we might just remove the empty lines at the start. However, this could cause some additional check files to not be tracked.

[szymon-rd]

this could cause some additional check files to not be tracked

What do you mean?
But I can do that, it's a minor cosmetic issue so I didn't pay much attention to it, but it may be better to follow some formatting rules when it doesn't impose much cost.

[nicolasstucki]

Should be squashed and rebased.

[szymon-rd]

@nicolasstucki thank you for the review! however, could you take a look at: #19241 ? It's the first PR. This one is the second one.

[szymon-rd]

@nicolasstucki I will squash it on merge, I removed the test.

[nicolasstucki]

I will squash it on merge

Do you mean click in the squash and merge button?

[szymon-rd]

Do you mean click in the squash and merge button?

Yes

[nicolasstucki]

Do you mean click in the squash and merge button?

Yes

One of the points of squashing is to have a clean commit message. That button concatenates the commit messages, which defeats the purpose.

[nicolasstucki]

It just needs a squash, rebase, and CI test again.

[szymon-rd]

One of the points of squashing is to have a clean commit message. That button concatenates the commit messages, which defeats the purpose.

I usually have pretty good experience with this approach - The PR title is kept as a git commit title (first paragraph), and the commits are put in the commit description (next paragraphs). GitHub and other tools I have used render it nicely. But I agree it's better to squash it now, as we have to rebase and CI test it again.

[nicolasstucki]

There was a conflict with tests/warn/i15474.scala