From: Josef Svenningsson <josef.svenningsson@gmail.com>
Date: Thu, 20 Apr 2006 21:36:22 +0000 (+0000)
Subject: Extcore can now handle data types without constructors
X-Git-Tag: Before_FC_branch_merge~527
X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=commitdiff_plain;h=4db2c92cedd11b90c6cec46c245b3b618f734d49

Extcore can now handle data types without constructors
---

diff --git a/compiler/coreSyn/MkExternalCore.lhs b/compiler/coreSyn/MkExternalCore.lhs
index 291b16e..b4970cc 100644
--- a/compiler/coreSyn/MkExternalCore.lhs
+++ b/compiler/coreSyn/MkExternalCore.lhs
@@ -64,7 +64,8 @@ collect_tdefs tcon tdefs
   where
     tdef | isNewTyCon tcon = 
                 C.Newtype (make_con_qid (tyConName tcon)) (map make_tbind tyvars) repclause 
-         | null (tyConDataCons tcon) = error "MkExternalCore died: can't handle datatype declarations with no data constructors"
+-- 20060420 GHC handles empty data types just fine. ExtCore should too! jds
+--         | null (tyConDataCons tcon) = error "MkExternalCore died: can't handle datatype declarations with no data constructors"
          | otherwise = 
                 C.Data (make_con_qid (tyConName tcon)) (map make_tbind tyvars) (map make_cdef (tyConDataCons tcon)) 
          where repclause | isRecursiveTyCon tcon = Nothing
diff --git a/compiler/parser/ParserCore.y b/compiler/parser/ParserCore.y
index 3210583..7b82eba 100644
--- a/compiler/parser/ParserCore.y
+++ b/compiler/parser/ParserCore.y
@@ -82,7 +82,7 @@ tdefs	:: { [TyClDecl RdrName] }
 	| tdef ';' tdefs	{$1:$3}
 
 tdef	:: { TyClDecl RdrName }
-	: '%data' q_tc_name tv_bndrs '=' '{' cons1 '}'
+	: '%data' q_tc_name tv_bndrs '=' '{' cons '}'
                 { mkTyData DataType (noLoc [], noLoc (ifaceExtRdrName $2), map toHsTvBndr $3) Nothing $6 Nothing }
 	| '%newtype' q_tc_name tv_bndrs trep 
 		{ let tc_rdr = ifaceExtRdrName $2 in
@@ -97,9 +97,9 @@ trep    :: { OccName -> [LConDecl RdrName] }
 			                in [noLoc $ ConDecl (noLoc dc_name) Explicit []
 					   (noLoc []) con_info ResTyH98]) }
 
-cons1	:: { [LConDecl RdrName] }
-	: con		{ [$1] }
-	| con ';' cons1	{ $1:$3 }
+cons	:: { [LConDecl RdrName] }
+	: {- empty -}	{ [] } -- 20060420 Empty data types allowed. jds
+	| con ';' cons	{ $1:$3 }
 
 con	:: { LConDecl RdrName }
 	: d_pat_occ attv_bndrs hs_atys