[GHC] #11102: `ghc --supported-extension` shall not list `TemplateHaskell` when unsupported

[GHC]

#11102: `ghc --supported-extension` shall not list `TemplateHaskell` when
unsupported
-------------------------------------+-------------------------------------
        Reporter:  hvr               |                Owner:  bgamari
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.0.1
       Component:  Compiler          |              Version:  7.10.2
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  phab:D1484
       Wiki Page:                    |
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Comment (by Herbert Valerio Riedel <hvr@…>):

 In [changeset:"7c9cbfd9074055d6db93d4b44c8aea8d32402aa6/ghc" 7c9cbfd/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="7c9cbfd9074055d6db93d4b44c8aea8d32402aa6"
 template-haskell: drop `TemplateHaskell` requirement

 `other-extensions: TemplateHaskell` is inaccurate: It's not required
 to compile `template-haskell` (otherwise we wouldn't be able to build
 that package via `ghc-stage1`...)

 This has been discovered while working on #11102
 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11102#comment:1>
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