[GHC] #14869: Documentation for isLiftedTypeKind is incorrect

[GHC]

#14869: Documentation for isLiftedTypeKind is incorrect
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Documentation     |  Unknown/Multiple
  bug                                |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D4474
       Wiki Page:                    |
-------------------------------------+-------------------------------------

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

 In [changeset:"49ac3f0f2a13f66fea31a258fa98b0de39bfbf10/ghc"
 49ac3f0f/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="49ac3f0f2a13f66fea31a258fa98b0de39bfbf10"
 Fix #14869 by being more mindful of Type vs. Constraint

 Summary:
 Before, we were using `isLiftedTypeKind` in `reifyType`
 before checking if a type was `Constraint`. But as it turns out,
 `isLiftedTypeKind` treats `Constraint` the same as `Type`, so every
 occurrence of `Constraint` would be reified as `Type`! To make things
 worse, the documentation for `isLiftedTypeKind` stated that it
 treats `Constraint` //differently// from `Type`, which simply isn't
 true.

 This revises the documentation for `isLiftedTypeKind` to reflect
 reality, and defers the `isLiftedTypeKind` check in `reifyType` so
 that it does not accidentally swallow `Constraint`.

 Test Plan: make test TEST=T14869

 Reviewers: goldfire, bgamari

 Reviewed By: goldfire

 Subscribers: rwbarton, thomie, carter

 GHC Trac Issues: #14869

 Differential Revision: https://phabricator.haskell.org/D4474
 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14869#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler