[GHC] #9209: Template haskell panic

[GHC]

#9209: Template haskell panic
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              Reporter:  tulcod      |            Owner:
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Compiler    |          Version:  7.8.2
            Resolution:              |         Keywords:
      Operating System:              |     Architecture:  Unknown/Multiple
  Unknown/Multiple                   |       Difficulty:  Unknown
       Type of failure:              |       Blocked By:
  None/Unknown                       |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
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Comment (by goldfire):

 Instead of implementing spliced declarations in more contexts, I'm just
 going to fix the panic and turn it into a sensible error message.

 In contrast to Simon's comment:2, not all the heavy lifting is done. To
 implement declaration splices in other contexts, it will be necessary to
 make rather drastic changes to the relevant AST nodes: we would need, say,
 an `HsLocalBinds` now to store declarations in the order they were
 written, so we can use declaration splices to break up mutually recursive
 blocks, as we do at top level. The same would have to be done for classes
 and instances. This would add up to quite a lot of code change, for a
 feature no one has actually requested. (I'm taking the original report to
 be a complaint about a panic, not a complaint about a missing splice
 feature.)

 All of this ''is'' possible, but it's more work than I wish to invest at
 the moment. Expect a patch soon fixing the error message, but if you want
 non-top-level declaration splices, please create a new ticket.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9209#comment:10>
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