hasLowerBound anyVersion

[mpilgrem]

The Haddock documentation for Distribution.Types.VersionRange.hasLowerBound explains (as it has since before Cabal-3.4.0.0):

-- | Does the version range have an explicit lower bound?
--
-- Note: this function only considers the user-specified lower bounds, but not
-- the implicit >=0 lower bound.

Before Cabal-3.4.0.0, hasLowerBound anyVersion was False (anyVersion was AnyVersion). From Cabal-3.4.0.0, hasLowerBound anyVersion is True (the data constructor AnyVersion is no more, and anyVersion is now OrLaterVersion (mkVersion [0])).

Is this change in behaviour of hasLowerBound anyVersion what was intended when AnyVersion was dropped? Or should hasLowerBound v now begin not (isAnyVersion v) || ...?

Alternatively, could the current Haddock documentation be clarified, for example:

-- | Does the version range have an explicit lower bound?
--
-- Note: this function only considers the user-specified lower bounds, but not
-- an implicit >=0 lower bound. @hasLowerBound anyVersion@ yields @True@ as
-- the >=0 lower bound is express.

Edit: Depending on what was intended, I can raise a pull request.

[gbaz]

I feel like this is a change in the meaning of anyVersion from AnyVersion more than a change to hasLowerBound. Not sure in what cases it would make a difference, generally?

[mpilgrem]

What prompted me to raise this was that Stack was relying on hasLowerBound to decide whether or not to add a lower bound in stack sdist --pvp-bounds lower - it only added a lower bound if one was not already expressed. When dependency my-package in a Cabal file went from meaning implied ">= 0" (AnyVersion) to meaning my-package >= 0 (express ">=0"), it stopped working (it is now fixed).

I doubt if different Haddock documentation would have headed off the Stack bug, but it might help somebody. Not least, because the data constructors of VersionRange are semi-opaque (they are exposed only in Distribution.Types.VersionRange.Internal).

[gbaz]

Thanks for this report, I think its a wart semantically and probably should be cleaned up (in making anyVersion not have a lower bound) In general the changes to version stuff left us in a somewhat partial state, and this is another instance of that.