Parse error?

[Kwanghoon Choi]

Hello,

When using GHC4.06, we met the following parse error message:

   ParseIface.hs:6827: Non-exhaustive patterns in case

We found that ParseIface.hs is generated from ParseIface.y by using 
Happy.  In that way, we generate the .hs, and we look into the 6827th line. 
The case expression in the line and its alternatives below seem to
concern Haskell tokens. However, we couldn't find any missing token,
which would give the above message.

   [ParseIface.hs generarted by Happy1.6]

   6824  happyNewToken action sts stk
   6825      = lexer(\tk ->
   6826      let cont i = action i i tk (HappyState action) sts stk in
-> 6827      case tk of {
   6828      ITeof -> action 217 217 (error "reading EOF!") (HappyState action) s ts 
stk;
   6829      ITcase -> cont 121;
   6830      ITclass -> cont 122;
   6831      ITdata -> cont 123;
   6832      ITdefault -> cont 124;
   ...       ...

Thanks in advance.

Kwanghoon Choi