X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;ds=sidebyside;f=ghc%2Fcompiler%2Frename%2FRnEnv.lhs;h=80b617484054bc5c9b248828f7c62b6608bcf90c;hb=798374a5fa613d622b70cd4c37bb97f203abb6ba;hp=15a46bfd9d51c985c4c2c263f3afa23003c230d6;hpb=794f1a1d1a11e5a8447e041bfbac37e5c3fb7cc1;p=ghc-hetmet.git

diff --git a/ghc/compiler/rename/RnEnv.lhs b/ghc/compiler/rename/RnEnv.lhs
index 15a46bf..80b6174 100644
--- a/ghc/compiler/rename/RnEnv.lhs
+++ b/ghc/compiler/rename/RnEnv.lhs
@@ -452,7 +452,14 @@ lookupBndrRn rdr_name
 		case lookupRdrEnv global_env (qualifyRdrName mod rdr_name) of
 		  Just (name:rest) -> ASSERT( null rest )
 				      returnRn name 
-		  Nothing	   -> pprPanic "lookupBndrRn" (ppr mod <+> ppr rdr_name)
+		  Nothing	   -> 	-- Almost always this case is a compiler bug.
+					-- But consider a type signature that doesn't have 
+					-- a corresponding binder: 
+					--	module M where { f :: Int->Int }
+					-- We use lookupSigOccRn, which uses lookupBndrRn (for good reasons)
+					-- and we don't want to panic.  So we report an out-of-scope error
+					failWithRn (mkUnboundName rdr_name)
+						   (unknownNameErr rdr_name)
     }
 
 -- lookupOccRn looks up an occurrence of a RdrName