[GHC] #11451: Inconsistent warnings for unused binders in type and instance declarations

[GHC]

#11451: Inconsistent warnings for unused binders in type and instance declarations
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        Reporter:  simonpj           |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.10.3
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D1825
       Wiki Page:                    |
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Comment (by RyanGlScott):

 I wholeheartedly agree with your points, although if we introduce a
 `-Wunused-foralls` flag, it will probably be confusing to also have
 `-Wunused-type-variables`, since `forall`-ed variables ''are'' type
 variables, after all. I think it might be better to rename `-Wunused-type-
 variables` to `-Wunused-type-patterns` in light of this (especially since
 you want to emphasize the distinction from `-Wunused-foralls`).

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11451#comment:32>
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