X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2Fmain%2FHscTypes.lhs;h=a76ec5a8744f7fb478cf8638f472cecad02aaead;hb=6c5705e398947a3b74a3f9b7cfb3dd93ca12b8e0;hp=a0e4857e448923fb96f94c75d7d1c8fc25ba74ae;hpb=d0c6c8b3979e6bd11edba434ccbc61105dcd2537;p=ghc-hetmet.git

diff --git a/compiler/main/HscTypes.lhs b/compiler/main/HscTypes.lhs
index a0e4857..a76ec5a 100644
--- a/compiler/main/HscTypes.lhs
+++ b/compiler/main/HscTypes.lhs
@@ -209,9 +209,15 @@ data TargetId
 pprTarget :: Target -> SDoc
 pprTarget (Target id _) = pprTargetId id
 
+instance Outputable Target where
+    ppr = pprTarget
+
 pprTargetId (TargetModule m) = ppr m
 pprTargetId (TargetFile f _) = text f
 
+instance Outputable TargetId where
+    ppr = pprTargetId
+
 type HomePackageTable  = ModuleNameEnv HomeModInfo
 	-- Domain = modules in the home package
 	-- "home" package name cached here for convenience
@@ -295,12 +301,15 @@ hptRules hsc_env deps
     , mod /= moduleName gHC_PRIM
 
 	-- Look it up in the HPT
-    , let mod_info = case lookupUFM hpt mod of
-		  	Nothing -> pprPanic "hptRules" (ppr mod <+> ppr deps)
-		  	Just x  -> x
+    , let rules = case lookupUFM hpt mod of
+		    Just info -> md_rules (hm_details info)
+		    Nothing -> pprTrace "WARNING in hptRules" msg [] 
+	  msg = vcat [ptext SLIT("missing module") <+> ppr mod,
+		      ptext SLIT("Probable cause: out-of-date interface files")]
+			-- This really shouldn't happen, but see Trac #962
 
 	-- And get its dfuns
-    , rule <- md_rules (hm_details mod_info) ]
+    , rule <- rules ]
 \end{code}
 
 %************************************************************************