[project @ 2005-01-27 10:44:00 by simonpj]

--------------------------------------------
          Replace hi-boot files with hs-boot files
  	--------------------------------------------

This major commit completely re-organises the way that recursive modules
are dealt with.

  * It should have NO EFFECT if you do not use recursive modules

  * It is a BREAKING CHANGE if you do

====== Warning: .hi-file format has changed, so if you are
======		updating into an existing HEAD build, you'll
======		need to make clean and re-make


The details:  [documentation still to be done]

* Recursive loops are now broken with Foo.hs-boot (or Foo.lhs-boot),
  not Foo.hi-boot

* An hs-boot files is a proper source file.  It is compiled just like
  a regular Haskell source file:
	ghc Foo.hs		generates Foo.hi, Foo.o
	ghc Foo.hs-boot		generates Foo.hi-boot, Foo.o-boot

* hs-boot files are precisely a subset of Haskell. In particular:
	- they have the same import, export, and scoping rules
	- errors (such as kind errors) in hs-boot files are checked
  You do *not* need to mention the "original" name of something in
  an hs-boot file, any more than you do in any other Haskell module.

* The Foo.hi-boot file generated by compiling Foo.hs-boot is a machine-
  generated interface file, in precisely the same format as Foo.hi

* When compiling Foo.hs, its exports are checked for compatibility with
  Foo.hi-boot (previously generated by compiling Foo.hs-boot)

* The dependency analyser (ghc -M) knows about Foo.hs-boot files, and
  generates appropriate dependencies.  For regular source files it
  generates
	Foo.o : Foo.hs
	Foo.o : Baz.hi		-- Foo.hs imports Baz
	Foo.o : Bog.hi-boot	-- Foo.hs source-imports Bog

  For a hs-boot file it generates similar dependencies
	Bog.o-boot : Bog.hs-boot
	Bog.o-boot : Nib.hi	-- Bog.hs-boto imports Nib

* ghc -M is also enhanced to use the compilation manager dependency
  chasing, so that
	ghc -M Main
  will usually do the job.  No need to enumerate all the source files.

* The -c flag is no longer a "compiler mode". It simply means "omit the
  link step", and synonymous with -no-link.

1 files changed, 9 insertions, 5 deletions

diff --git a/ghc/utils/ghc-pkg/Main.hs b/ghc/utils/ghc-pkg/Main.hs
index ce1e0b5bc1..d6da9146f0 100644
--- a/ghc/utils/ghc-pkg/Main.hs
+++ b/ghc/utils/ghc-pkg/Main.hs
@@ -309,7 +309,7 @@ registerPackage :: FilePath
 		-> IO ()
 registerPackage input defines db_stack auto_ghci_libs update force = do
   let
-	db_to_operate_on = head db_stack
+	db_to_operate_on = my_head "db" db_stack
 	db_filename	 = fst db_to_operate_on
   --
   checkConfigAccess db_filename
@@ -541,7 +541,7 @@ checkDuplicates db_stack pkg update = do
   when (not update && exposed pkg && not (null exposed_pkgs_with_same_name)) $
 	die ("trying to register " ++ showPackageId pkgid 
 		  ++ " as exposed, but "
-		  ++ showPackageId (package (head exposed_pkgs_with_same_name))
+		  ++ showPackageId (package (my_head "when" exposed_pkgs_with_same_name))
 		  ++ " is also exposed.")
 
 
@@ -633,9 +633,10 @@ updatePackageDB db_stack pkgs new_pkg = do
 	resolveDep pkgid
 	   | realVersion pkgid  = pkgid
 	   | otherwise		= lookupDep (pkgName pkgid)
-	
+--	   = pkgid
+
 	lookupDep name
-	   = head [ pid | p <- concat (map snd db_stack), 
+	   = my_head "dep" [ pid | p <- concat (map snd db_stack), 
 			  let pid = package p,
 			  pkgName pid == name ]
 
@@ -768,7 +769,7 @@ oldRunit clis = do
 
   let auto_ghci_libs = any isAuto clis 
 	 where isAuto OF_AutoGHCiLibs = True; isAuto _ = False
-      input_file = head ([ f | (OF_Input f) <- clis] ++ ["-"])
+      input_file = my_head "inp" ([ f | (OF_Input f) <- clis] ++ ["-"])
 
       force = OF_Force `elem` clis
       
@@ -786,6 +787,9 @@ oldRunit clis = do
     _            -> do prog <- getProgramName
 		       die (usageInfo (usageHeader prog) flags)
 
+my_head s [] = error s
+my_head s (x:xs) = x
+
 -- ---------------------------------------------------------------------------
 
 #ifdef OLD_STUFF