[GHC] #14678: GHc 8.4.1-alpha's bundled transformers doesn't correspond to a tagged release

[GHC]

#14678: GHc 8.4.1-alpha's bundled transformers doesn't correspond to a tagged
release
-------------------------------------+-------------------------------------
           Reporter:  RyanGlScott    |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  high           |         Milestone:  8.4.1
          Component:  Compiler       |           Version:  8.4.1-alpha1
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  None/Unknown
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 GHC 8.4.1-alpha claims to be bundled with `transformers-0.5.4.0`, but this
 isn't true. That's because it's using `transformers` commit
 http://git.haskell.org/packages/transformers.git/commit/36311d39bc545261dab85d4a27af562db1868ed6,
 which happened somewhere in between the `0.5.4.0` and `0.5.5.0` releases.

 This is actually a problem for me in practice because that commit gives a
 `Semigroup` instance for `Constant` which should have only been introduced
 in `0.5.5.0`, according to the
 [https://hackage.haskell.org/package/transformers-0.5.5.0/changelog
 changelog]. But commit 36311d39bc545261dab85d4a27af562db1868ed6 uses
 version `0.5.4.0`, which makes it impossible to guard against the
 existence of this instance using CPP (see [https://travis-ci.org/ekmett
 /transformers-compat/jobs/329285046#L739 this Travis build failure] for an
 example of this problem occurring).

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14678>
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