Version in Data.Version from base is defined as:

    data Version = Version { versionBranch :: [Int], versionTags :: [String] }

    instance Eq Version where

      v1 == v2  =  versionBranch v1 == versionBranch v2

                    && sort (versionTags v1) == sort (versionTags v2)

                    -- tags may be in any order

    instance Ord Version where

      v1 `compare` v2 = versionBranch v1 `compare` versionBranch v2

## Proposal

Remove the `versionTags` field from this type.

## Motivation

* The Eq and Ord instances of Version don't agree whether two versions with different versionTags are equal or not [1]:

    > a = Version [1] ["a"]

    > b = Version [1] ["b"]

    > compare a b

    EQ

    > a == b

    False

* The Package versioning policy does not include version tags [2].

* Cabal no longer supports package version tags [3,4].

Discussion period: 2 weeks.

Note: this is not a proposal to ignore trailing zeros when comparing versions. Neither is this is a proposal to change the Eq instance for Version to only consider the versionBranch field. This is a proposal to remove versionTags altogether.

[1] https://ghc.haskell.org/trac/ghc/ticket/2496

[2] http://www.haskell.org/haskellwiki/Package_versioning_policy

[3] https://github.com/haskell/cabal/issues/890

[4] http://www.haskell.org/cabal/users-guide/developing-packages.html#package-names-and-versions