Don't put uniqs in ghc wrapper function names; part of #4012

The wrapper functions can end up in interface files, and thus are
part of the ABI hash. But uniqs easily change for no good reason
when recompiling, which can lead to an ABI hash needlessly changing.

compiler/deSugar/DsForeign.lhs

@@ -44,10 +44,12 @@ import FastString
 import DynFlags
 import Platform
 import Config
+import Encoding
 import OrdList
 import Pair
 import Util
 
+import Data.IORef
 import Data.Maybe
 import Data.List
 \end{code}
@@ -211,11 +213,19 @@ dsFCall fn_id co fcall mDeclHeader = do
     (fcall', cDoc) <-
               case fcall of
               CCall (CCallSpec (StaticTarget cName mPackageId isFun) CApiConv safety) ->
-               do fcall_uniq <- newUnique
-                  let wrapperName = mkFastString "ghc_wrapper_" `appendFS`
-                                    mkFastString (showPpr dflags fcall_uniq) `appendFS`
-                                    mkFastString "_" `appendFS`
-                                    cName
+               do let wrapperRef = nextWrapperNum dflags
+                  wrapperNum <- liftIO $ readIORef wrapperRef
+                  liftIO $ writeIORef wrapperRef (wrapperNum + 1)
+                  thisMod <- getModuleDs
+                  let pkg = packageIdString  (modulePackageId thisMod)
+                      mod = moduleNameString (moduleName      thisMod)
+                      wrapperNameComponents = ["ghc_wrapper",
+                                               show wrapperNum,
+                                               pkg, mod,
+                                               unpackFS cName]
+                      wrapperName = mkFastString
+                                  $ zEncodeString
+                                  $ intercalate ":" wrapperNameComponents
                       fcall' = CCall (CCallSpec (StaticTarget wrapperName mPackageId True) CApiConv safety)
                       c = includes
                        $$ fun_proto <+> braces (cRet <> semi)

compiler/main/DynFlags.hs

@@ -690,7 +690,9 @@ data DynFlags = DynFlags {
 
   interactivePrint      :: Maybe String,
 
-  llvmVersion           :: IORef (Int)
+  llvmVersion           :: IORef (Int),
+
+  nextWrapperNum        :: IORef Int
  }
 
 class HasDynFlags m where
@@ -1111,12 +1113,14 @@ initDynFlags dflags = do
  refFilesToNotIntermediateClean <- newIORef []
  refGeneratedDumps <- newIORef Set.empty
  refLlvmVersion <- newIORef 28
+ wrapperNum <- newIORef 0
  return dflags{
         filesToClean   = refFilesToClean,
         dirsToClean    = refDirsToClean,
         filesToNotIntermediateClean = refFilesToNotIntermediateClean,
         generatedDumps = refGeneratedDumps,
-        llvmVersion    = refLlvmVersion
+        llvmVersion    = refLlvmVersion,
+        nextWrapperNum = wrapperNum
         }
 
 -- | The normal 'DynFlags'. Note that they is not suitable for use in this form
@@ -1239,7 +1243,8 @@ defaultDynFlags mySettings =
         traceLevel = 1,
         profAuto = NoProfAuto,
         llvmVersion = panic "defaultDynFlags: No llvmVersion",
-        interactivePrint = Nothing
+        interactivePrint = Nothing,
+        nextWrapperNum = panic "defaultDynFlags: No nextWrapperNum"
       }
 
 defaultWays :: Settings -> [Way]