Generalise Package Support

This patch pushes through one fundamental change: a module is now
identified by the pair of its package and module name, whereas
previously it was identified by its module name alone.  This means
that now a program can contain multiple modules with the same name, as
long as they belong to different packages.

This is a language change - the Haskell report says nothing about
packages, but it is now necessary to understand packages in order to
understand GHC's module system.  For example, a type T from module M
in package P is different from a type T from module M in package Q.
Previously this wasn't an issue because there could only be a single
module M in the program.

The "module restriction" on combining packages has therefore been
lifted, and a program can contain multiple versions of the same
package.

Note that none of the proposed syntax changes have yet been
implemented, but the architecture is geared towards supporting import
declarations qualified by package name, and that is probably the next
step.

It is now necessary to specify the package name when compiling a
package, using the -package-name flag (which has been un-deprecated).
Fortunately Cabal still uses -package-name.

Certain packages are "wired in".  Currently the wired-in packages are:
base, haskell98, template-haskell and rts, and are always referred to
by these versionless names.  Other packages are referred to with full
package IDs (eg. "network-1.0").  This is because the compiler needs
to refer to entities in the wired-in packages, and we didn't want to
bake the version of these packages into the comiler.  It's conceivable
that someone might want to upgrade the base package independently of
GHC.

Internal changes:

  - There are two module-related types:

        ModuleName      just a FastString, the name of a module
        Module          a pair of a PackageId and ModuleName

    A mapping from ModuleName can be a UniqFM, but a mapping from Module
    must be a FiniteMap (we provide it as ModuleEnv).

  - The "HomeModules" type that was passed around the compiler is now
    gone, replaced in most cases by the current package name which is
    contained in DynFlags.  We can tell whether a Module comes from the
    current package by comparing its package name against the current
    package.

  - While I was here, I changed PrintUnqual to be a little more useful:
    it now returns the ModuleName that the identifier should be qualified
    with according to the current scope, rather than its original
    module.  Also, PrintUnqual tells whether to qualify module names with
    package names (currently unused).

Docs to follow.

1 files changed, 24 insertions, 24 deletions

diff --git a/compiler/codeGen/ClosureInfo.lhs b/compiler/codeGen/ClosureInfo.lhs
index 84d9dd95ef..d137d4d3ca 100644
--- a/compiler/codeGen/ClosureInfo.lhs
+++ b/compiler/codeGen/ClosureInfo.lhs
@@ -61,8 +61,8 @@ import SMRep		-- all of it
 
 import CLabel
 
-import Constants	( mIN_PAYLOAD_SIZE )
-import Packages		( isDllName, HomeModules )
+import Packages		( isDllName )
+import PackageConfig	( PackageId )
 import StaticFlags	( opt_SccProfilingOn, opt_OmitBlackHoling,
 			  opt_Parallel, opt_DoTickyProfiling )
 import Id		( Id, idType, idArity, idName )
@@ -330,15 +330,15 @@ mkClosureInfo is_static id lf_info tot_wds ptr_wds srt_info descr
     name   = idName id
     sm_rep = chooseSMRep is_static lf_info tot_wds ptr_wds
 
-mkConInfo :: HomeModules
+mkConInfo :: PackageId
 	  -> Bool	-- Is static
 	  -> DataCon	
 	  -> Int -> Int	-- Total and pointer words
 	  -> ClosureInfo
-mkConInfo hmods is_static data_con tot_wds ptr_wds
+mkConInfo this_pkg is_static data_con tot_wds ptr_wds
    = ConInfo {	closureSMRep = sm_rep,
 		closureCon = data_con,
-		closureDllCon = isDllName hmods (dataConName data_con) }
+		closureDllCon = isDllName this_pkg (dataConName data_con) }
   where
     sm_rep = chooseSMRep is_static (mkConLFInfo data_con) tot_wds ptr_wds
 \end{code}
@@ -560,30 +560,30 @@ data CallMethod
 	CLabel 				--   The code label
 	Int 				--   Its arity
 
-getCallMethod :: HomeModules
+getCallMethod :: PackageId
 	      -> Name		-- Function being applied
 	      -> LambdaFormInfo	-- Its info
 	      -> Int		-- Number of available arguments
 	      -> CallMethod
 
-getCallMethod hmods name lf_info n_args
+getCallMethod this_pkg name lf_info n_args
   | nodeMustPointToIt lf_info && opt_Parallel
   =	-- If we're parallel, then we must always enter via node.  
 	-- The reason is that the closure may have been 	
 	-- fetched since we allocated it.
     EnterIt
 
-getCallMethod hmods name (LFReEntrant _ arity _ _) n_args
+getCallMethod this_pkg name (LFReEntrant _ arity _ _) n_args
   | n_args == 0    = ASSERT( arity /= 0 )
 		     ReturnIt	-- No args at all
   | n_args < arity = SlowCall	-- Not enough args
-  | otherwise      = DirectEntry (enterIdLabel hmods name) arity
+  | otherwise      = DirectEntry (enterIdLabel this_pkg name) arity
 
-getCallMethod hmods name (LFCon con) n_args
+getCallMethod this_pkg name (LFCon con) n_args
   = ASSERT( n_args == 0 )
     ReturnCon con
 
-getCallMethod hmods name (LFThunk _ _ updatable std_form_info is_fun) n_args
+getCallMethod this_pkg name (LFThunk _ _ updatable std_form_info is_fun) n_args
   | is_fun 	-- Must always "call" a function-typed 
   = SlowCall	-- thing, cannot just enter it [in eval/apply, the entry code
 		-- is the fast-entry code]
@@ -598,24 +598,24 @@ getCallMethod hmods name (LFThunk _ _ updatable std_form_info is_fun) n_args
 
   | otherwise	-- Jump direct to code for single-entry thunks
   = ASSERT( n_args == 0 )
-    JumpToIt (thunkEntryLabel hmods name std_form_info updatable)
+    JumpToIt (thunkEntryLabel this_pkg name std_form_info updatable)
 
-getCallMethod hmods name (LFUnknown True) n_args
+getCallMethod this_pkg name (LFUnknown True) n_args
   = SlowCall -- might be a function
 
-getCallMethod hmods name (LFUnknown False) n_args
+getCallMethod this_pkg name (LFUnknown False) n_args
   = ASSERT2 ( n_args == 0, ppr name <+> ppr n_args ) 
     EnterIt -- Not a function
 
-getCallMethod hmods name (LFBlackHole _) n_args
+getCallMethod this_pkg name (LFBlackHole _) n_args
   = SlowCall	-- Presumably the black hole has by now
 		-- been updated, but we don't know with
 		-- what, so we slow call it
 
-getCallMethod hmods name (LFLetNoEscape 0) n_args
+getCallMethod this_pkg name (LFLetNoEscape 0) n_args
   = JumpToIt (enterReturnPtLabel (nameUnique name))
 
-getCallMethod hmods name (LFLetNoEscape arity) n_args
+getCallMethod this_pkg name (LFLetNoEscape arity) n_args
   | n_args == arity = DirectEntry (enterReturnPtLabel (nameUnique name)) arity
   | otherwise = pprPanic "let-no-escape: " (ppr name <+> ppr arity)
 
@@ -845,12 +845,12 @@ closureLabelFromCI _ = panic "closureLabelFromCI"
 -- thunkEntryLabel is a local help function, not exported.  It's used from both
 -- entryLabelFromCI and getCallMethod.
 
-thunkEntryLabel hmods thunk_id (ApThunk arity) is_updatable
+thunkEntryLabel this_pkg thunk_id (ApThunk arity) is_updatable
   = enterApLabel is_updatable arity
-thunkEntryLabel hmods thunk_id (SelectorThunk offset) upd_flag
+thunkEntryLabel this_pkg thunk_id (SelectorThunk offset) upd_flag
   = enterSelectorLabel upd_flag offset
-thunkEntryLabel hmods thunk_id _ is_updatable
-  = enterIdLabel hmods thunk_id
+thunkEntryLabel this_pkg thunk_id _ is_updatable
+  = enterIdLabel this_pkg thunk_id
 
 enterApLabel is_updatable arity
   | tablesNextToCode = mkApInfoTableLabel is_updatable arity
@@ -860,9 +860,9 @@ enterSelectorLabel upd_flag offset
   | tablesNextToCode = mkSelectorInfoLabel upd_flag offset
   | otherwise        = mkSelectorEntryLabel upd_flag offset
 
-enterIdLabel hmods id
-  | tablesNextToCode = mkInfoTableLabel hmods id
-  | otherwise        = mkEntryLabel hmods id
+enterIdLabel this_pkg id
+  | tablesNextToCode = mkInfoTableLabel this_pkg id
+  | otherwise        = mkEntryLabel this_pkg id
 
 enterLocalIdLabel id
   | tablesNextToCode = mkLocalInfoTableLabel id