[GHC] #5664: Missing checks for FFI declaration types

[GHC]

#5664: Missing checks for FFI declaration types
---------------------------------+------------------------------------------
    Reporter:  simonmar          |        Owner:                             
        Type:  bug               |       Status:  new                        
    Priority:  normal            |    Milestone:  7.6.1                      
   Component:  Compiler (FFI)    |      Version:  7.2.1                      
    Keywords:                    |     Testcase:                             
   Blockedby:                    |   Difficulty:                             
          Os:  Unknown/Multiple  |     Blocking:                             
Architecture:  Unknown/Multiple  |      Failure:  GHC accepts invalid program
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 A `foreign import "wrapper"` should have the form `f -> IO (FunPtr f)`,
 and a `foreign import "dynamic"` should have the form `FunPtr f -> f`.
 GHC currently lacks these checks; the type argument to the `FunPtr` is
 ignored in both cases.

 Ian Lynagh's example is below; we should be rejecting `mkFun2` and
 `mkCallback2`.

 {{{
 module A where

 import Foreign
 import Foreign.C

 data D = D

 foreign import ccall "dynamic"
   mkFun1 :: FunPtr (CInt -> IO ()) -> (CInt -> IO ())

 foreign import ccall "dynamic"
   mkFun2 :: FunPtr (D -> IO ()) -> (CInt -> IO ())

 foreign import ccall "wrapper"
   mkCallBack1 :: IO () -> IO (FunPtr (IO ()))

 foreign import ccall "wrapper"
   mkCallBack2 :: IO () -> IO (FunPtr D)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5664>
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