[GHC] #10600: -fwarn-incomplete-patterns doesn't work with -fno-code

[GHC]

#10600: -fwarn-incomplete-patterns doesn't work with -fno-code
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        Reporter:  akio              |                Owner:  ezyang
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.4.1
       Component:  Compiler          |              Version:  7.10.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect         |  Unknown/Multiple
  warning at compile-time            |            Test Case:  driver/T8101b
      Blocked By:                    |             Blocking:
 Related Tickets:  #8101             |  Differential Rev(s):  Phab:D1278
       Wiki Page:                    |
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Comment (by duog):

 I have had a look at this issue and I think the situation must have
 changed somewhat since the last time a fix was attempted.
 Several errors can be thrown during desugaring now, including at least
 - Top-level bindings for unlifted types aren't allowed:
 - Top-level strict pattern bindings aren't allowed:
 which I assume must not have previously been the case?

 If I add an unconditional desugaring in HscMain.finishTypecheckOnly then
 haddock errors on Ghc.Prim with "Top-level bindings for unlifted types
 aren't allowed:"

 This means that currently these desugaring errors are not thrown for
 modules compiled with -fno-code.

 I have pushed D3533 which includes a test for this.

 Let's add a special case to skip desugaring of Ghc.Prim?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10600#comment:20>
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