[GHC] #14624: HEAD panic in ghc:DsForeign: toCType

[GHC]

#14624: HEAD panic in ghc:DsForeign: toCType
-------------------------------------+-------------------------------------
           Reporter:  tianxiaogu     |             Owner:  (none)
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Compiler       |           Version:  8.2.2
           Keywords:                 |  Operating System:  Linux
       Architecture:  x86_64         |   Type of failure:  Compile-time
  (amd64)                            |  crash or panic
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
-------------------------------------+-------------------------------------
 The following program crashes in 8.2.2 and HEAD (8.5.20171228).

 {{{#!hs
 {-# LANGUAGE ForeignFunctionInterface, CApiFFI, GHCForeignImportPrim,
              QuasiQuotes, TemplateHaskell, JavaScriptFFI, MagicHash,
              UnliftedFFITypes #-}

 module TH_foreignCallingConventions where

 import GHC.Prim
 import Control.Applicative
 import Language.Haskell.TH
 import System.IO
 import Foreign.Ptr

 $( do let fi cconv safety lbl name ty =
             ForeignD (ImportF cconv safety lbl name ty)
       dec1 <- fi CCall      Interruptible "&"   (mkName "foo") <$> [t| Ptr
 () |]
       dec2 <- fi CApi       Safe          "bar" (mkName "bar") <$> [t|
 Int# -> Int# |]
       -- the declarations below would result in warnings or errors when
 returned
       dec3 <- fi CApi       Unsafe        "baz" (mkName "baz") <$> [t|
 Double -> IO () |]
       dec4 <- fi StdCall    Safe          "bay" (mkName "bay") <$> [t|
 (Int -> Bool) -> IO Int |]
       dec5 <- fi JavaScript Unsafe        "bax" (mkName "bax") <$> [t| Ptr
 Int -> IO String |]
       runIO $
         mapM_ (putStrLn . pprint) [dec1, dec2, dec3, dec4, dec5] >> hFlush
 stdout
       return [dec1, dec2]
  )
 }}}

 This program is derived by mutating test TH_foreignCallingConventions.hs.

 {{{#!diff
 diff --git a/testsuite/tests/th/TH_foreignCallingConventions.hs
 b/testsuite/tests/th/TH_foreignCallingConventions.hs
 index ee39510..16789af 100644
 --- a/testsuite/tests/th/TH_foreignCallingConventions.hs
 +++ b/testsuite/tests/th/TH_foreignCallingConventions.hs
 @@ -13,7 +13,7 @@ import Foreign.Ptr
  $( do let fi cconv safety lbl name ty =
              ForeignD (ImportF cconv safety lbl name ty)
        dec1 <- fi CCall      Interruptible "&"   (mkName "foo") <$> [t|
 Ptr () |]
 -      dec2 <- fi Prim       Safe          "bar" (mkName "bar") <$> [t|
 Int# -> Int# |]
 +      dec2 <- fi CApi       Safe          "bar" (mkName "bar") <$> [t|
 Int# -> Int# |]
        -- the declarations below would result in warnings or errors when
 returned
        dec3 <- fi CApi       Unsafe        "baz" (mkName "baz") <$> [t|
 Double -> IO () |]
        dec4 <- fi StdCall    Safe          "bay" (mkName "bay") <$> [t|
 (Int -> Bool) -> IO Int |]
 }}}

 Log:

 {{{
 foreign import capi safe "bar" bar :: GHC.Prim.Int# ->
                                       GHC.Prim.Int#
 foreign import capi unsafe "baz" baz :: GHC.Types.Double ->
                                         GHC.Types.IO ()
 foreign import stdcall safe "bay" bay :: (GHC.Types.Int ->
                                           GHC.Types.Bool) ->
                                          GHC.Types.IO GHC.Types.Int
 foreign import javascript unsafe "bax" bax :: GHC.Ptr.Ptr GHC.Types.Int ->
                                               GHC.Types.IO GHC.Base.String
 ghc: panic! (the 'impossible' happened)
   (GHC version 8.5.20171228 for x86_64-unknown-linux):
         toCType
   Int#
   Call stack:
       CallStack (from HasCallStack):
         callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in
 ghc:Outputable
         pprPanic, called at compiler/deSugar/DsForeign.hs:730:17 in
 ghc:DsForeign

 Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

 }}}

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14624>
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