Re: #16411: Inconsistent -Wpartial-fields warnings with (~) vs. (~~)

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#16411: Inconsistent -Wpartial-fields warnings with (~) vs. (~~)
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        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.6.4
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  error/warning at compile-time      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |  https://gitlab.haskell.org/ghc/ghc/merge_requests/520
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Comment (by Marge Bot <ben+marge-bot@…>):

 In [changeset:"36546a43e490ea6f989e6cad369d1a251c94a42b/ghc" 36546a4/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="36546a43e490ea6f989e6cad369d1a251c94a42b"
 Fix #16411 by making dataConCannotMatch aware of (~~)

 The `dataConCannotMatch` function (which powers the
 `-Wpartial-fields` warning, among other things) had special reasoning
 for explicit equality constraints of the form `a ~ b`, but it did
 not extend that reasoning to `a ~~ b` constraints, leading to #16411.
 Easily fixed.
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/16411#comment:2>