Do not #include external header files when compiling via C

This has several advantages:

 - -fvia-C is consistent with -fasm with respect to FFI declarations:
   both bind to the ABI, not the API.

 - foreign calls can now be inlined freely across module boundaries, since
   a header file is not required when compiling the call.

 - bootstrapping via C will be more reliable, because this difference
   in behavour between the two backends has been removed.

There is one disadvantage:

 - we get no checking by the C compiler that the FFI declaration
   is correct.

So now, the c-includes field in a .cabal file is always ignored by
GHC, as are header files specified in an FFI declaration.  This was
previously the case only for -fasm compilations, now it is also the
case for -fvia-C too.

3 files changed, 9 insertions, 41 deletions

diff --git a/compiler/main/CodeOutput.lhs b/compiler/main/CodeOutput.lhs
index d6e130946c..fd67f2173a 100644
--- a/compiler/main/CodeOutput.lhs
+++ b/compiler/main/CodeOutput.lhs
@@ -24,7 +24,6 @@ import PprC		( writeCs )
 import CmmLint		( cmmLint )
 import Packages
 import Util
-import FastString	( unpackFS )
 import Cmm		( RawCmm )
 import HscTypes
 import DynFlags
@@ -32,7 +31,6 @@ import DynFlags
 import ErrUtils		( dumpIfSet_dyn, showPass, ghcExit )
 import Outputable
 import Module
-import List		( nub )
 import Maybes		( firstJust )
 
 import Distribution.Package	( showPackageId )
@@ -81,9 +79,7 @@ codeOutput dflags this_mod location foreign_stubs pkg_deps flat_abstractC
 	; case hscTarget dflags of {
              HscInterpreted -> return ();
              HscAsm         -> outputAsm dflags filenm flat_abstractC;
-             HscC           -> outputC dflags filenm this_mod location 
-				 flat_abstractC stubs_exist pkg_deps
-				 foreign_stubs;
+             HscC           -> outputC dflags filenm flat_abstractC pkg_deps;
              HscJava        -> 
 #ifdef JAVA
 			       outputJava dflags filenm mod_name tycons core_binds;
@@ -108,15 +104,12 @@ doOutput filenm io_action = bracket (openFile filenm WriteMode) hClose io_action
 
 \begin{code}
 outputC :: DynFlags
-        -> FilePath -> Module -> ModLocation
+        -> FilePath
         -> [RawCmm]
-        -> (Bool, Bool)
         -> [PackageId]
-        -> ForeignStubs
         -> IO ()
 
-outputC dflags filenm mod location flat_absC 
-	(stub_h_exists, _) packages foreign_stubs
+outputC dflags filenm flat_absC packages
   = do 
        -- figure out which header files to #include in the generated .hc file:
        --
@@ -124,38 +117,22 @@ outputC dflags filenm mod location flat_absC
        --   * -#include options from the cmdline and OPTIONS pragmas
        --   * the _stub.h file, if there is one.
        --
-       pkg_configs <- getPreloadPackagesAnd dflags packages
-       let pkg_names = map (showPackageId.package) pkg_configs
-
-       c_includes <- getPackageCIncludes pkg_configs
-       let cmdline_includes = cmdlineHcIncludes dflags -- -#include options
-       
-	   ffi_decl_headers 
-	      = case foreign_stubs of
-		  NoStubs 		-> []
-		  ForeignStubs _ _ fdhs -> map unpackFS (nub fdhs)
-			-- Remove duplicates, because distinct foreign import decls
-			-- may cite the same #include.  Order doesn't matter.
-
-           all_headers =  c_includes
-		       ++ reverse cmdline_includes
-		       ++ ffi_decl_headers
+       let rts = getPackageDetails (pkgState dflags) rtsPackageId
                        
-       let cc_injects = unlines (map mk_include all_headers)
+       let cc_injects = unlines (map mk_include (includes rts))
        	   mk_include h_file = 
        	    case h_file of 
        	       '"':_{-"-} -> "#include "++h_file
        	       '<':_      -> "#include "++h_file
        	       _          -> "#include \""++h_file++"\""
 
+       pkg_configs <- getPreloadPackagesAnd dflags packages
+       let pkg_names = map (showPackageId.package) pkg_configs
+
        doOutput filenm $ \ h -> do
 	  hPutStr h ("/* GHC_PACKAGES " ++ unwords pkg_names ++ "\n*/\n")
 	  hPutStr h cc_injects
-	  when stub_h_exists $ 
-	     hPutStrLn h ("#include \"" ++ inc_stub_h ++ "\"")
 	  writeCs dflags h flat_absC
-  where
-    (_, _, inc_stub_h) = mkStubPaths dflags (moduleName mod) location
 \end{code}
 
 
@@ -226,7 +203,7 @@ outputForeignStubs dflags mod location stubs
 	stub_h_exists <- doesFileExist stub_h
 	return (stub_h_exists, stub_c_exists)
 
-   ForeignStubs h_code c_code _ -> do
+   ForeignStubs h_code c_code -> do
 	let
 	    stub_c_output_d = pprCode CStyle c_code
 	    stub_c_output_w = showSDoc stub_c_output_d
diff --git a/compiler/main/HscTypes.lhs b/compiler/main/HscTypes.lhs
index ec872626d0..ffb66eed59 100644
--- a/compiler/main/HscTypes.lhs
+++ b/compiler/main/HscTypes.lhs
@@ -629,9 +629,6 @@ data ForeignStubs = NoStubs
                                       	-- 	"foreign exported" functions
 			SDoc 		-- C stubs to use when calling
                                         -- 	"foreign exported" functions
-			[FastString] 	-- Headers that need to be included
-				        -- 	into C code generated for this module
-
 \end{code}
 
 \begin{code}
diff --git a/compiler/main/Packages.lhs b/compiler/main/Packages.lhs
index 982085437c..a7c01aef6a 100644
--- a/compiler/main/Packages.lhs
+++ b/compiler/main/Packages.lhs
@@ -19,7 +19,6 @@ module Packages (
 
 	-- * Inspecting the set of packages in scope
 	getPackageIncludePath,
-	getPackageCIncludes,
 	getPackageLibraryPath,
 	getPackageLinkOpts,
 	getPackageExtraCcOpts,
@@ -593,11 +592,6 @@ getPackageIncludePath dflags pkgs = do
   ps <- getPreloadPackagesAnd dflags pkgs
   return (nub (filter notNull (concatMap includeDirs ps)))
 
-	-- includes are in reverse dependency order (i.e. rts first)
-getPackageCIncludes :: [PackageConfig] -> IO [String]
-getPackageCIncludes pkg_configs = do
-  return (reverse (nub (filter notNull (concatMap includes pkg_configs))))
-
 getPackageLibraryPath :: DynFlags -> [PackageId] -> IO [String]
 getPackageLibraryPath dflags pkgs = do 
   ps <- getPreloadPackagesAnd dflags pkgs