[GHC] #15857: Need for better warnings arising from StarIsType extension

[GHC]

#15857: Need for better warnings arising from StarIsType extension
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        Reporter:  jrp               |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  low               |            Milestone:
       Component:  Compiler          |              Version:  8.6.1
      Resolution:                    |             Keywords:  StarIsType
                                     |  NoStarIsType
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Poor/confusing    |  Unknown/Multiple
  error message                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Description changed by jrp:

Old description:

> If I redefine `type (*) = (,)` I am given not given a warning that it
> doesn't do what I expect, when building with cabal new-repl or cabal new-
> build, because the `StarIsType` extension is now enabled by default.
> Instead or a warning, I get (correct but confusing) error messages.

New description:

 If I redefine `type (*) = (,)` I am given not given a warning that it
 doesn't do what I expect, when building with cabal new-repl or cabal new-
 build, because the `StarIsType` extension is now enabled by default.
 Instead of a warning, I get (correct but confusing) error messages.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15857#comment:1>
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