From bbc652466faf9f4809d7aaf840be5be861fcd49f Mon Sep 17 00:00:00 2001
From: sof <unknown>
Date: Fri, 7 May 1999 13:41:14 +0000
Subject: [PATCH] [project @ 1999-05-07 13:41:14 by sof] Fixed two
 showstopping bugs in 'deriving Read' code (mea culpa).

---
 ghc/compiler/typecheck/TcGenDeriv.lhs |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/ghc/compiler/typecheck/TcGenDeriv.lhs b/ghc/compiler/typecheck/TcGenDeriv.lhs
index e017cf2..bb27993 100644
--- a/ghc/compiler/typecheck/TcGenDeriv.lhs
+++ b/ghc/compiler/typecheck/TcGenDeriv.lhs
@@ -840,7 +840,7 @@ gen_Read_binds fixities tycon
 				 ])
 	      | lab_fields == 0 =  -- common case.
     		  snd (mapAccumL mk_qual 
-				 c_Expr 
+				 d_Expr 
 				 (zipWithEqual "as_needed" 
 					       (\ con_field draw_from -> (mk_read_qual 10 con_field,
 									  draw_from))
@@ -891,8 +891,9 @@ gen_Read_binds fixities tycon
 	     | not is_infix  = 9
 	     | otherwise     = getFixity fixities dc_nm
 
-	   read_paren_arg  = -- parens depend on precedence...
-	     HsPar (genOpApp a_Expr gt_RDR (HsLit (HsInt paren_prec_limit)))
+	   read_paren_arg   -- parens depend on precedence...
+	    | nullary_con  = false_Expr -- it's optional.
+	    | otherwise    = HsPar (genOpApp a_Expr gt_RDR (HsLit (HsInt paren_prec_limit)))
 
 \end{code}
 
-- 
1.7.10.4