Expunge ThFake, cure Trac #2632

This patch fixes a dirty hack (the fake ThFake module), which in turn
was causing Trac #2632.

The new scheme is that the top-level binders in a TH [d| ... |] decl splice
get Internal names.  That breaks a previous invariant that things like
TyCons always have External names, but these TyCons are never long-lived;
they live only long enough to typecheck the TH quotation; the result is
discarded.  So it seems cool.

Nevertheless -- Template Haskell folk: please test your code.  The testsuite
is OK but it's conceivable that I've broken something in TH.  Let's see.

1 files changed, 10 insertions, 3 deletions

diff --git a/compiler/iface/IfaceEnv.lhs b/compiler/iface/IfaceEnv.lhs
index 20d7327cfe..e09ff41d12 100644
--- a/compiler/iface/IfaceEnv.lhs
+++ b/compiler/iface/IfaceEnv.lhs
@@ -114,9 +114,16 @@ newImplicitBinder :: Name			-- Base name
 -- For source type/class decls, this is the first occurrence
 -- For iface ones, the LoadIface has alrady allocated a suitable name in the cache
 newImplicitBinder base_name mk_sys_occ
-  = newGlobalBinder (nameModule base_name)
-		    (mk_sys_occ (nameOccName base_name))
-		    (nameSrcSpan base_name)    
+  | Just mod <- nameModule_maybe base_name
+  = newGlobalBinder mod occ loc
+  | otherwise	  	-- When typechecking a [d| decl bracket |], 
+    			-- TH generates types, classes etc with Internal names,
+			-- so we follow suit for the implicit binders
+  = do	{ uniq <- newUnique
+	; return (mkInternalName uniq occ loc) }
+  where
+    occ = mk_sys_occ (nameOccName base_name)
+    loc = nameSrcSpan base_name
 
 ifaceExportNames :: [IfaceExport] -> TcRnIf gbl lcl [AvailInfo]
 ifaceExportNames exports = do