[GHC] #14288: ScopedTypeVariables with nested foralls broken since 8.0.2

[GHC]

#14288: ScopedTypeVariables with nested foralls broken since 8.0.2
-------------------------------------+-------------------------------------
        Reporter:  MikolajKonarski   |                Owner:  RyanGlScott
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler (Type    |              Version:  8.2.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Linux             |         Architecture:  x86_64
 Type of failure:  GHC rejects       |  (amd64)
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14498            |  Differential Rev(s):  Phab:D4272
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ryan Scott <ryan.gl.scott@…>):

 In [changeset:"b6304f8fd9b845466116874db4224f42acbc597d/ghc" b6304f8/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="b6304f8fd9b845466116874db4224f42acbc597d"
 Document ScopedTypeVariables' interaction with nested foralls

 Summary:
 This documents the status quo with regards to how
 `ScopedTypeVariables` brings into scope type variables that are
 quantified by nested `forall`s (that is to say, it doesn't). This
 takes the prose in
 https://ghc.haskell.org/trac/ghc/ticket/14288#comment:5
 and enshrines it into the users' guide.

 Test Plan: Read it

 Reviewers: simonpj, bgamari

 Reviewed By: simonpj

 Subscribers: rwbarton, thomie, carter

 GHC Trac Issues: #14288

 Differential Revision: https://phabricator.haskell.org/D4272
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14288#comment:24>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler