X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=compiler%2FdeSugar%2FMatchLit.lhs;h=e0a76011b6119137a62cdda39858b363e4a18932;hb=b334ad284ffdbc251ed8cab9ba41977424400a88;hp=2cdab30bf8b162c0059b9182b1eab6385bdfb7b7;hpb=90dc9026b091be5cca5da4c6cbd3713ecc493361;p=ghc-hetmet.git

diff --git a/compiler/deSugar/MatchLit.lhs b/compiler/deSugar/MatchLit.lhs
index 2cdab30..e0a7601 100644
--- a/compiler/deSugar/MatchLit.lhs
+++ b/compiler/deSugar/MatchLit.lhs
@@ -183,7 +183,8 @@ matchLiterals :: [Id]
 	      -> DsM MatchResult
 
 matchLiterals (var:vars) ty sub_groups
-  = do	{	-- Deal with each group
+  = ASSERT( all notNull sub_groups )
+    do	{	-- Deal with each group
 	; alts <- mapM match_group sub_groups
 
 	 	-- Combine results.  For everything except String