[project @ 2001-03-13 14:58:25 by simonpj]

----------------
	Nuke ClassContext
	----------------

This commit tidies up a long-standing inconsistency in GHC.
The context of a class or instance decl used to be restricted
to predicates of the form
	C t1 .. tn
with
	type ClassContext = [(Class,[Type])]

but everywhere else in the compiler we used

	type ThetaType = [PredType]
where PredType can be any sort of constraint (= predicate).

The inconsistency actually led to a crash, when compiling
	class (?x::Int) => C a where {}

I've tidied all this up by nuking ClassContext altogether, and using
PredType throughout.  Lots of modified files, but all in
more-or-less trivial ways.

I've also added a check that the context of a class or instance
decl doesn't include a non-inheritable predicate like (?x::Int).

Other things

 * rename constructor 'Class' from type TypeRep.Pred to 'ClassP'
   (makes it easier to grep for)

 * rename constructor HsPClass  => HsClassP
		      HsPIParam => HsIParam

1 files changed, 3 insertions, 1 deletions

diff --git a/ghc/compiler/main/CodeOutput.lhs b/ghc/compiler/main/CodeOutput.lhs
index 1e33654169..33357fcbc2 100644
--- a/ghc/compiler/main/CodeOutput.lhs
+++ b/ghc/compiler/main/CodeOutput.lhs
@@ -35,6 +35,7 @@ import CmdLineOpts	( DynFlags, HscLang(..), dopt_OutName )
 import TmpFiles		( newTempName )
 
 import IO		( IOMode(..), hClose, openFile, Handle )
+import IO		( hPutStr, stderr) 	-- Debugging
 \end{code}
 
 
@@ -81,7 +82,8 @@ codeOutput dflags mod_name tycons core_binds stg_binds
 
 doOutput :: String -> (Handle -> IO ()) -> IO ()
 doOutput filenm io_action
-  = (do	handle <- openFile filenm WriteMode
+  = (do	hPutStr stderr ("Writing to" ++ filenm)
+	handle <- openFile filenm WriteMode
 	io_action handle
 	hClose handle)
     `catch` (\err -> pprPanic "Failed to open or write code output file"