filesystem: fix upgrade

[lazka]

msys2-base was removed from dash and filesystem, but filesystem gets updated
first and then fails beause it would break dash which hasn't been updated yet.

So add the provides back.

This fixes:

error: failed to prepare transaction (could not satisfy dependencies)
:: installing filesystem (2020.02-3) breaks dependency 'msys2-base' required by dash

[marler8997]

So it sounds like filesystem will have to maintain this provides=('msys2-base') for the forseeable future if we want to avoid this error when upgrading filesystem from the current or previous versions to a newer one.

It seems like the better solution would be to fix pacman to handle when provides are removed and the upgraded versions of their dependents (in this case dash) no longer require them.

If pacman is unable to upgrade a package because it has removed a provides that is needed by another package, shouldn't it save that operation and come back to it later after attempting to upgrade the rest of the packages? In this case, it would fail to upgrade filesystem because it no longer provides msys2-base and dash depends on it, but then it could continue on and eventually upgrade dash which will no longer depend on msys2-base then it can come back to any packages that previously failed and retry. It seems like an mechanism like this would be much more robust.

[marler8997]

For reference, looks like this is the PR that caused the issue: #1984

[lazka]

If pacman is unable to upgrade a package because it has removed a provides that is needed by another package, shouldn't it save that operation and come back to it later after attempting to upgrade the rest of the packages? In this case, it would fail to upgrade filesystem because it no longer provides msys2-base and dash depends on it, but then it could continue on and eventually upgrade dash which will no longer depend on msys2-base then it can come back to any packages that previously failed and retry. It seems like an mechanism like this would be much more robust.

The problem is that we have a "core update group" thingy which gets always update first, which contains filesystem and not dash. pacman can handle this all just fine, we break it by splitting the update into two parts. We need to think about getting rid/reducing the "core update group"..

[marler8997]

The problem is that we have a "core update group" thingy which gets always update first, which contains filesystem and not dash. pacman can handle this all just fine, we break it by splitting the update into two parts. We need to think about getting rid/reducing the "core update group"..

Oh I see, thanks for that explanation.

[pqnet]

For anyone ending up here and looking for a workaround: this is fixed if you upgrade manually dash by running pacman -S dash

[lazka]

@Alexpux thanks!