[hoc-cvs] [hoc] r388 committed - Have another shot at fixing the cabal build (issue #12)....

[<cod...@go...>]

Revision: 388
Author: wol...@gm...
Date: Tue Aug 11 11:23:05 2009
Log: Have another shot at fixing the cabal build (issue #12).

HOC_cbits.o is passed in via c-sources; Setup.hs now contains a hack that  
prevents the
"ghc: no input files" problem.

To be exact: the custom build hook arranges for a short shell script to be  
called
instead of ghc. This shell script checks whether it is being called on  
HOC_cbits.o
and silently ignores that command. For all other parameters, it invokes the  
actual ghc.

http://code.google.com/p/hoc/source/detail?r=388

Modified:
  /trunk/hoc/HOC.cabal
  /trunk/hoc/Setup.hs

=======================================
--- /trunk/hoc/HOC.cabal	Sat Feb 14 12:53:11 2009
+++ /trunk/hoc/HOC.cabal	Tue Aug 11 11:23:05 2009
@@ -64,7 +64,16 @@
      hs-source-dirs: HOC

      extra-libraries: objc, ffi
+
+        -- This is a hack.
+        -- Setup.hs contains code to build HOC_cbits.o from the
+        -- objective-c sources, as well as a matching hack to prevent
+        -- Cabal from invoking "ghc -c" on this file. Cabal will then
+        -- include HOC_cbits.o on the linker command line, which is the
+        -- whole point of this exercise.
      c-sources: HOC_cbits.o
+
+
      if os(darwin)
          include-dirs: /usr/include/ffi
          frameworks: Foundation
=======================================
--- /trunk/hoc/Setup.hs	Sun Dec 21 13:42:00 2008
+++ /trunk/hoc/Setup.hs	Tue Aug 11 11:23:05 2009
@@ -5,6 +5,7 @@
  import Distribution.Simple.PreProcess
  import Distribution.Simple.Configure
  import Distribution.Simple.LocalBuildInfo
+import Distribution.Simple.Program
  import System.Cmd( system )
  import System.Exit( ExitCode(..) )
  import System.Environment( getEnv )
@@ -99,6 +100,13 @@

      extraFlags <- buildCBits (libBuildInfo libInfo)

+    -- add compiler flags required by C parts of HOC;
+    --
+    -- HACK #1:
+    -- This passes the HOC_cbits.o object file on the
+    -- as a compiler flag so that template haskell can link
+    -- compile-time code.
+
      let hooked_pd = pd
                  { library = Just $ libInfo
                          { libBuildInfo = addCompilerFlags extraFlags
@@ -109,7 +117,42 @@
                          (executables pd)
                  }

-    build hooked_pd lbi buildFlags knownSuffixHandlers
+    -- HACK #2:
+    -- HOC_cbits.o (built by buildCBits below) is specified in c-sources
+    -- for the library. Cabal reacts to this by invoking ghc -c  
HOC_cbits.o,
+    -- which ghc doesn't like. So, instead of calling ghc directly, we call
+    -- a short auto-generated shell script that does nothing in this case,
+    -- and calls the real ghc in all other cases.
+    -- After having "compiled" HOC_cbits.o in this way, Cabal will link
+    -- HOC_cbits.o as part of the library, which is what we want.
+
+    let Just pr = lookupKnownProgram "ghc" (withPrograms lbi)
+        Just conf = lookupProgram pr (withPrograms lbi)
+
+        ghcLocation = programLocation conf
+
+    let fakeGHC = "./dist/build/fake-ghc.sh"
+
+    writeFile fakeGHC $ unlines [
+            "#!/bin/sh -e",
+            "case \"$*\" in",
+            "    *HOC_cbits.o) true;;",
+            "    *) \"" ++ locationPath ghcLocation ++ "\" \"$@\";;",
+            "esac"
+        ]
+    system $ "chmod +x " ++ fakeGHC
+
+    let conf' = conf { programLocation = UserSpecified fakeGHC }
+
+        progs' = updateProgram conf' (withPrograms lbi)
+
+    let lbi' = lbi {
+                    withPrograms = progs'
+                }
+
+    -- call the default with our modified package description and
+    -- local build info
+    build hooked_pd lbi' buildFlags knownSuffixHandlers

  -- |Build HOC_cbits.o using the flags specified in the configuration
  -- stage, and return a list of flags to add to support usage of