semicolons

[Ross Paterson]

Haskell 98 allows things separated by semicolons to be empty, unlike
earlier versions.  Hugs implements this for decls and ldecls, but not
other contexts, e.g. it rejects stuff like

	module Foo where {import A;;x = 1;;y = 2;}
	do {;;;x <- [1];;;return x;;}

The attached patch fixes this for impDecls, topDecls and stmts.
That leaves alts, I think.
-------------------------------------------------------------------
Index: src/parser.y
===================================================================
RCS file: /cvs/hugs98/src/parser.y,v
retrieving revision 1.33
diff -u -r1.33 parser.y
--- src/parser.y	2002/06/14 14:41:10	1.33
+++ src/parser.y	2002/07/15 11:21:15
@@ -163,7 +163,8 @@
 					  }
 					}
 	  ;
-modBody	  : topDecls			{$$ = $1;}
+modBody	  : /* empty */			{$$ = gc0(NIL);}
+	  | topDecls			{$$ = gc1($1);}
 	  | impDecls chase		{$$ = gc2(NIL);}
 	  | impDecls ';' chase topDecls	{$$ = gc4($4);}
 	  ;
@@ -203,6 +204,7 @@
 /*- Import declarations: --------------------------------------------------*/
 
 impDecls  : impDecls ';' impDecl	{imps = cons($3,imps); $$=gc3(NIL);}
+	  | impDecls ';'		{$$=gc2(NIL);}
 	  | impDecl			{imps = singleton($1); $$=gc1(NIL);}
 	  ;
 chase	  : /* empty */			{if (chase(imps)) {
@@ -260,13 +262,9 @@
 
 /*- Top-level declarations: -----------------------------------------------*/
 
-topDecls  : /* empty */			{$$ = gc0(NIL);}
-	  | ';'				{$$ = gc1(NIL);}
-	  | topDecls1			{$$ = $1;}
-	  | topDecls1 ';'		{$$ = gc2($1);}
-	  ;
-topDecls1 : topDecls1 ';' topDecl	{$$ = gc2($1);}
-	  | topDecls1 ';' decl		{$$ = gc3(cons($3,$1));}
+topDecls  : topDecls ';'		{$$ = gc2($1);}
+	  | topDecls ';' topDecl	{$$ = gc2($1);}
+	  | topDecls ';' decl		{$$ = gc3(cons($3,$1));}
 	  | topDecl			{$$ = gc0(NIL);}
 	  | decl			{$$ = gc1(cons($1,NIL));}
 	  ;
@@ -879,11 +877,9 @@
 	  | guardAlt			{$$ = gc1(cons($1,NIL));}
 	  ;
 guardAlt  : '|' exp0 ARROW exp		{$$ = gc4(pair($3,pair($2,$4)));}
-	  ;
-stmts	  : stmts1 ';'			{$$ = gc2($1);}
-	  | stmts1			{$$ = $1;}
 	  ;
-stmts1    : stmts1 ';' stmt		{$$ = gc3(cons($3,$1));}
+stmts	  : stmts ';' stmt		{$$ = gc3(cons($3,$1));}
+	  | stmts ';'			{$$ = gc2($1);}
 	  | stmt			{$$ = gc1(cons($1,NIL));}
 	  ;
 stmt      : exp_err FROM exp		{$$ = gc3(ap(FROMQUAL,pair($1,$3)));}