Make plpgsql support FOR over a query specified by a cursor declaration,

for improved compatibility with Oracle.

Pavel Stehule, with some fixes by me.

src/pl/plpgsql/src/gram.y

@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.109 2008/04/01 03:51:09 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.110 2008/04/06 23:43:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -50,6 +50,8 @@ static	void			 plpgsql_sql_error_callback(void *arg);
 static	char			*check_label(const char *yytxt);
 static	void			 check_labels(const char *start_label,
 									  const char *end_label);
+static PLpgSQL_expr 	*read_cursor_args(PLpgSQL_var *cursor,
+										  int until, const char *expected);
 
 %}
 
@@ -861,21 +863,15 @@ stmt_for		: opt_block_label K_FOR for_control loop_body
 							new->body	  = $4.stmts;
 							$$ = (PLpgSQL_stmt *) new;
 						}
-						else if ($3->cmd_type == PLPGSQL_STMT_FORS)
-						{
-							PLpgSQL_stmt_fors		*new;
-
-							new = (PLpgSQL_stmt_fors *) $3;
-							new->label	  = $1;
-							new->body	  = $4.stmts;
-							$$ = (PLpgSQL_stmt *) new;
-						}
 						else
 						{
-							PLpgSQL_stmt_dynfors	*new;
+							PLpgSQL_stmt_forq		*new;
 
-							Assert($3->cmd_type == PLPGSQL_STMT_DYNFORS);
-							new = (PLpgSQL_stmt_dynfors *) $3;
+							Assert($3->cmd_type == PLPGSQL_STMT_FORS ||
+								   $3->cmd_type == PLPGSQL_STMT_FORC ||
+								   $3->cmd_type == PLPGSQL_STMT_DYNFORS);
+							/* forq is the common supertype of all three */
+							new = (PLpgSQL_stmt_forq *) $3;
 							new->label	  = $1;
 							new->body	  = $4.stmts;
 							$$ = (PLpgSQL_stmt *) new;
@@ -892,9 +888,9 @@ for_control		:
 					{
 						int			tok = yylex();
 
-						/* Simple case: EXECUTE is a dynamic FOR loop */
 						if (tok == K_EXECUTE)
 						{
+							/* EXECUTE means it's a dynamic FOR loop */
 							PLpgSQL_stmt_dynfors	*new;
 							PLpgSQL_expr			*expr;
 							int						term;
@@ -942,6 +938,47 @@ for_control		:
 
 							$$ = (PLpgSQL_stmt *) new;
 						}
+						else if (tok == T_SCALAR &&
+								 yylval.scalar->dtype == PLPGSQL_DTYPE_VAR &&
+								 ((PLpgSQL_var *) yylval.scalar)->datatype->typoid == REFCURSOROID)
+						{
+							/* It's FOR var IN cursor */
+							PLpgSQL_stmt_forc	*new;
+							PLpgSQL_var			*cursor = (PLpgSQL_var *) yylval.scalar;
+							char				*varname;
+
+							new = (PLpgSQL_stmt_forc *) palloc0(sizeof(PLpgSQL_stmt_forc));
+							new->cmd_type = PLPGSQL_STMT_FORC;
+							new->lineno = $1;
+
+							new->curvar = cursor->varno;
+
+							/* Should have had a single variable name */
+							plpgsql_error_lineno = $2.lineno;
+							if ($2.scalar && $2.row)
+								ereport(ERROR,
+										(errcode(ERRCODE_SYNTAX_ERROR),
+										 errmsg("cursor FOR loop must have just one target variable")));
+
+							/* create loop's private RECORD variable */
+							plpgsql_convert_ident($2.name, &varname, 1);
+							new->rec = plpgsql_build_record(varname,
+															$2.lineno,
+															true);
+
+							/* can't use an unbound cursor this way */
+							if (cursor->cursor_explicit_expr == NULL)
+								ereport(ERROR,
+										(errcode(ERRCODE_SYNTAX_ERROR),
+										 errmsg("cursor FOR loop must use a bound cursor variable")));
+
+							/* collect cursor's parameters if any */
+							new->argquery = read_cursor_args(cursor,
+															 K_LOOP,
+															 "LOOP");
+
+							$$ = (PLpgSQL_stmt *) new;
+						}
 						else
 						{
 							PLpgSQL_expr	*expr1;
@@ -1412,81 +1449,8 @@ stmt_open		: K_OPEN lno cursor_variable
 						}
 						else
 						{
-							if ($3->cursor_explicit_argrow >= 0)
-							{
-								char   *cp;
-
-								tok = yylex();
-								if (tok != '(')
-								{
-									plpgsql_error_lineno = plpgsql_scanner_lineno();
-									ereport(ERROR,
-											(errcode(ERRCODE_SYNTAX_ERROR),
-											 errmsg("cursor \"%s\" has arguments",
-													$3->refname)));
-								}
-
-								/*
-								 * Push back the '(', else read_sql_stmt
-								 * will complain about unbalanced parens.
-								 */
-								plpgsql_push_back_token(tok);
-
-								new->argquery = read_sql_stmt("SELECT ");
-
-								/*
-								 * Now remove the leading and trailing parens,
-								 * because we want "select 1, 2", not
-								 * "select (1, 2)".
-								 */
-								cp = new->argquery->query;
-
-								if (strncmp(cp, "SELECT", 6) != 0)
-								{
-									plpgsql_error_lineno = plpgsql_scanner_lineno();
-									/* internal error */
-									elog(ERROR, "expected \"SELECT (\", got \"%s\"",
-										 new->argquery->query);
-								}
-								cp += 6;
-								while (*cp == ' ') /* could be more than 1 space here */
-									cp++;
-								if (*cp != '(')
-								{
-									plpgsql_error_lineno = plpgsql_scanner_lineno();
-									/* internal error */
-									elog(ERROR, "expected \"SELECT (\", got \"%s\"",
-										 new->argquery->query);
-								}
-								*cp = ' ';
-
-								cp += strlen(cp) - 1;
-
-								if (*cp != ')')
-									yyerror("expected \")\"");
-								*cp = '\0';
-							}
-							else
-							{
-								tok = yylex();
-								if (tok == '(')
-								{
-									plpgsql_error_lineno = plpgsql_scanner_lineno();
-									ereport(ERROR,
-											(errcode(ERRCODE_SYNTAX_ERROR),
-											 errmsg("cursor \"%s\" has no arguments",
-													$3->refname)));
-								}
-
-								if (tok != ';')
-								{
-									plpgsql_error_lineno = plpgsql_scanner_lineno();
-									ereport(ERROR,
-											(errcode(ERRCODE_SYNTAX_ERROR),
-											 errmsg("syntax error at \"%s\"",
-													yytext)));
-								}
-							}
+							/* predefined cursor query, so read args */
+							new->argquery = read_cursor_args($3, ';', ";");
 						}
 
 						$$ = (PLpgSQL_stmt *)new;
@@ -2578,6 +2542,97 @@ check_labels(const char *start_label, const char *end_label)
 	}
 }
 
+/*
+ * Read the arguments (if any) for a cursor, followed by the until token
+ *
+ * If cursor has no args, just swallow the until token and return NULL.
+ * If it does have args, we expect to see "( expr [, expr ...] )" followed
+ * by the until token.  Consume all that and return a SELECT query that
+ * evaluates the expression(s) (without the outer parens).
+ */
+static PLpgSQL_expr *
+read_cursor_args(PLpgSQL_var *cursor, int until, const char *expected)
+{
+	PLpgSQL_expr *expr;
+	int			tok;
+	char	   *cp;
+
+	tok = yylex();
+	if (cursor->cursor_explicit_argrow < 0)
+	{
+		/* No arguments expected */
+		if (tok == '(')
+		{
+			plpgsql_error_lineno = plpgsql_scanner_lineno();
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("cursor \"%s\" has no arguments",
+							cursor->refname)));
+		}
+
+		if (tok != until)
+		{
+			plpgsql_error_lineno = plpgsql_scanner_lineno();
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("syntax error at \"%s\"",
+							yytext)));
+		}
+
+		return NULL;
+	}
+
+	/* Else better provide arguments */
+	if (tok != '(')
+	{
+		plpgsql_error_lineno = plpgsql_scanner_lineno();
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("cursor \"%s\" has arguments",
+						cursor->refname)));
+	}
+
+	/*
+	 * Push back the '(', else plpgsql_read_expression
+	 * will complain about unbalanced parens.
+	 */
+	plpgsql_push_back_token(tok);
+
+	expr = plpgsql_read_expression(until, expected);
+
+	/*
+	 * Now remove the leading and trailing parens,
+	 * because we want "SELECT 1, 2", not "SELECT (1, 2)".
+	 */
+	cp = expr->query;
+
+	if (strncmp(cp, "SELECT", 6) != 0)
+	{
+		plpgsql_error_lineno = plpgsql_scanner_lineno();
+		/* internal error */
+		elog(ERROR, "expected \"SELECT (\", got \"%s\"", expr->query);
+	}
+	cp += 6;
+	while (*cp == ' ')			/* could be more than 1 space here */
+		cp++;
+	if (*cp != '(')
+	{
+		plpgsql_error_lineno = plpgsql_scanner_lineno();
+		/* internal error */
+		elog(ERROR, "expected \"SELECT (\", got \"%s\"", expr->query);
+	}
+	*cp = ' ';
+
+	cp += strlen(cp) - 1;
+
+	if (*cp != ')')
+		yyerror("expected \")\"");
+	*cp = '\0';
+
+	return expr;
+}
+
+
 /* Needed to avoid conflict between different prefix settings: */
 #undef yylex
 

src/pl/plpgsql/src/pl_comp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.123 2008/03/27 03:57:34 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.124 2008/04/06 23:43:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -575,25 +575,11 @@ do_compile(FunctionCallInfo fcinfo,
 						 errhint("You probably want to use TG_NARGS and TG_ARGV instead.")));
 
 			/* Add the record for referencing NEW */
-			rec = palloc0(sizeof(PLpgSQL_rec));
-			rec->dtype = PLPGSQL_DTYPE_REC;
-			rec->refname = pstrdup("new");
-			rec->tup = NULL;
-			rec->tupdesc = NULL;
-			rec->freetup = false;
-			plpgsql_adddatum((PLpgSQL_datum *) rec);
-			plpgsql_ns_additem(PLPGSQL_NSTYPE_REC, rec->recno, rec->refname);
+			rec = plpgsql_build_record("new", 0, true);
 			function->new_varno = rec->recno;
 
 			/* Add the record for referencing OLD */
-			rec = palloc0(sizeof(PLpgSQL_rec));
-			rec->dtype = PLPGSQL_DTYPE_REC;
-			rec->refname = pstrdup("old");
-			rec->tup = NULL;
-			rec->tupdesc = NULL;
-			rec->freetup = false;
-			plpgsql_adddatum((PLpgSQL_datum *) rec);
-			plpgsql_ns_additem(PLPGSQL_NSTYPE_REC, rec->recno, rec->refname);
+			rec = plpgsql_build_record("old", 0, true);
 			function->old_varno = rec->recno;
 
 			/* Add the variable tg_name */
@@ -1481,21 +1467,10 @@ plpgsql_build_variable(const char *refname, int lineno, PLpgSQL_type *dtype,
 			}
 		case PLPGSQL_TTYPE_REC:
 			{
-				/*
-				 * "record" type -- build a variable-contents record variable
-				 */
+				/* "record" type -- build a record variable */
 				PLpgSQL_rec *rec;
 
-				rec = palloc0(sizeof(PLpgSQL_rec));
-				rec->dtype = PLPGSQL_DTYPE_REC;
-				rec->refname = pstrdup(refname);
-				rec->lineno = lineno;
-
-				plpgsql_adddatum((PLpgSQL_datum *) rec);
-				if (add2namespace)
-					plpgsql_ns_additem(PLPGSQL_NSTYPE_REC,
-									   rec->recno,
-									   refname);
+				rec = plpgsql_build_record(refname, lineno, add2namespace);
 				result = (PLpgSQL_variable *) rec;
 				break;
 			}
@@ -1515,6 +1490,28 @@ plpgsql_build_variable(const char *refname, int lineno, PLpgSQL_type *dtype,
 	return result;
 }
 
+/*
+ * Build empty named record variable, and optionally add it to namespace
+ */
+PLpgSQL_rec *
+plpgsql_build_record(const char *refname, int lineno, bool add2namespace)
+{
+	PLpgSQL_rec *rec;
+
+	rec = palloc0(sizeof(PLpgSQL_rec));
+	rec->dtype = PLPGSQL_DTYPE_REC;
+	rec->refname = pstrdup(refname);
+	rec->lineno = lineno;
+	rec->tup = NULL;
+	rec->tupdesc = NULL;
+	rec->freetup = false;
+	plpgsql_adddatum((PLpgSQL_datum *) rec);
+	if (add2namespace)
+		plpgsql_ns_additem(PLPGSQL_NSTYPE_REC, rec->recno, rec->refname);
+
+	return rec;
+}
+
 /*
  * Build a row-variable data structure given the pg_class OID.
  */

src/pl/plpgsql/src/pl_funcs.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_funcs.c,v 1.68 2008/04/01 03:51:09 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_funcs.c,v 1.69 2008/04/06 23:43:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -482,6 +482,8 @@ plpgsql_stmt_typename(PLpgSQL_stmt *stmt)
 			return _("FOR with integer loop variable");
 		case PLPGSQL_STMT_FORS:
 			return _("FOR over SELECT rows");
+		case PLPGSQL_STMT_FORC:
+			return _("FOR over cursor");
 		case PLPGSQL_STMT_EXIT:
 			return "EXIT";
 		case PLPGSQL_STMT_RETURN:
@@ -528,6 +530,7 @@ static void dump_loop(PLpgSQL_stmt_loop *stmt);
 static void dump_while(PLpgSQL_stmt_while *stmt);
 static void dump_fori(PLpgSQL_stmt_fori *stmt);
 static void dump_fors(PLpgSQL_stmt_fors *stmt);
+static void dump_forc(PLpgSQL_stmt_forc *stmt);
 static void dump_exit(PLpgSQL_stmt_exit *stmt);
 static void dump_return(PLpgSQL_stmt_return *stmt);
 static void dump_return_next(PLpgSQL_stmt_return_next *stmt);
@@ -581,6 +584,9 @@ dump_stmt(PLpgSQL_stmt *stmt)
 		case PLPGSQL_STMT_FORS:
 			dump_fors((PLpgSQL_stmt_fors *) stmt);
 			break;
+		case PLPGSQL_STMT_FORC:
+			dump_forc((PLpgSQL_stmt_forc *) stmt);
+			break;
 		case PLPGSQL_STMT_EXIT:
 			dump_exit((PLpgSQL_stmt_exit *) stmt);
 			break;
@@ -775,6 +781,29 @@ dump_fors(PLpgSQL_stmt_fors *stmt)
 	printf("    ENDFORS\n");
 }
 
+static void
+dump_forc(PLpgSQL_stmt_forc *stmt)
+{
+	dump_ind();
+	printf("FORC %s ",  stmt->rec->refname);
+	printf("curvar=%d\n", stmt->curvar);
+
+	dump_indent += 2;
+	if (stmt->argquery != NULL)
+	{
+		dump_ind();
+		printf("  arguments = ");
+		dump_expr(stmt->argquery);
+		printf("\n");
+	}
+	dump_indent -= 2;
+
+	dump_stmts(stmt->body);
+
+	dump_ind();
+	printf("    ENDFORC\n");
+}
+
 static void
 dump_open(PLpgSQL_stmt_open *stmt)
 {

src/pl/plpgsql/src/plpgsql.h

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.96 2008/04/01 03:51:09 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/plpgsql.h,v 1.97 2008/04/06 23:43:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -80,6 +80,7 @@ enum
 	PLPGSQL_STMT_WHILE,
 	PLPGSQL_STMT_FORI,
 	PLPGSQL_STMT_FORS,
+	PLPGSQL_STMT_FORC,
 	PLPGSQL_STMT_EXIT,
 	PLPGSQL_STMT_RETURN,
 	PLPGSQL_STMT_RETURN_NEXT,
@@ -409,6 +410,21 @@ typedef struct
 } PLpgSQL_stmt_fori;
 
 
+/*
+ * PLpgSQL_stmt_forq represents a FOR statement running over a SQL query.
+ * It is the common supertype of PLpgSQL_stmt_fors, PLpgSQL_stmt_forc
+ * and PLpgSQL_dynfors.
+ */
+typedef struct
+{
+	int			cmd_type;
+	int			lineno;
+	char	   *label;
+	PLpgSQL_rec *rec;
+	PLpgSQL_row *row;
+	List	   *body;			/* List of statements */
+} PLpgSQL_stmt_forq;
+
 typedef struct
 {								/* FOR statement running over SELECT	*/
 	int			cmd_type;
@@ -416,10 +432,23 @@ typedef struct
 	char	   *label;
 	PLpgSQL_rec *rec;
 	PLpgSQL_row *row;
-	PLpgSQL_expr *query;
 	List	   *body;			/* List of statements */
+	/* end of fields that must match PLpgSQL_stmt_forq */
+	PLpgSQL_expr *query;
 } PLpgSQL_stmt_fors;
 
+typedef struct
+{								/* FOR statement running over cursor	*/
+	int			cmd_type;
+	int			lineno;
+	char	   *label;
+	PLpgSQL_rec *rec;
+	PLpgSQL_row *row;
+	List	   *body;			/* List of statements */
+	/* end of fields that must match PLpgSQL_stmt_forq */
+	int			curvar;
+	PLpgSQL_expr *argquery;		/* cursor arguments if any */
+} PLpgSQL_stmt_forc;
 
 typedef struct
 {								/* FOR statement running over EXECUTE	*/
@@ -428,8 +457,9 @@ typedef struct
 	char	   *label;
 	PLpgSQL_rec *rec;
 	PLpgSQL_row *row;
-	PLpgSQL_expr *query;
 	List	   *body;			/* List of statements */
+	/* end of fields that must match PLpgSQL_stmt_forq */
+	PLpgSQL_expr *query;
 	List	   *params;			/* USING expressions */
 } PLpgSQL_stmt_dynfors;
 
@@ -738,6 +768,8 @@ extern PLpgSQL_type *plpgsql_build_datatype(Oid typeOid, int32 typmod);
 extern PLpgSQL_variable *plpgsql_build_variable(const char *refname, int lineno,
 					   PLpgSQL_type *dtype,
 					   bool add2namespace);
+extern PLpgSQL_rec *plpgsql_build_record(const char *refname, int lineno,
+										 bool add2namespace);
 extern PLpgSQL_condition *plpgsql_parse_err_condition(char *condname);
 extern void plpgsql_adddatum(PLpgSQL_datum *new);
 extern int	plpgsql_add_initdatums(int **varnos);

src/test/regress/expected/plpgsql.out

@@ -3151,3 +3151,119 @@ NOTICE:  6
         26
 (1 row)
 
+-- test FOR-over-cursor
+create or replace function forc01() returns void as $$
+declare
+  c cursor(r1 integer, r2 integer)
+       for select * from generate_series(r1,r2) i;
+  c2 cursor
+       for select * from generate_series(41,43) i;
+begin
+  for r in c(5,7) loop
+    raise notice '% from %', r.i, c;
+  end loop;
+  -- again, to test if cursor was closed properly
+  for r in c(9,10) loop
+    raise notice '% from %', r.i, c;
+  end loop;
+  -- and test a parameterless cursor
+  for r in c2 loop
+    raise notice '% from %', r.i, c2;
+  end loop;
+  -- and try it with a hand-assigned name
+  raise notice 'after loop, c2 = %', c2;
+  c2 := 'special_name';
+  for r in c2 loop
+    raise notice '% from %', r.i, c2;
+  end loop;
+  raise notice 'after loop, c2 = %', c2;
+  -- and try it with a generated name
+  -- (which we can't show in the output because it's variable)
+  c2 := null;
+  for r in c2 loop
+    raise notice '%', r.i;
+  end loop;
+  raise notice 'after loop, c2 = %', c2;
+  return;
+end;
+$$ language plpgsql;
+select forc01();
+NOTICE:  5 from c
+NOTICE:  6 from c
+NOTICE:  7 from c
+NOTICE:  9 from c
+NOTICE:  10 from c
+NOTICE:  41 from c2
+NOTICE:  42 from c2
+NOTICE:  43 from c2
+NOTICE:  after loop, c2 = c2
+NOTICE:  41 from special_name
+NOTICE:  42 from special_name
+NOTICE:  43 from special_name
+NOTICE:  after loop, c2 = special_name
+NOTICE:  41
+NOTICE:  42
+NOTICE:  43
+NOTICE:  after loop, c2 = <NULL>
+ forc01 
+--------
+ 
+(1 row)
+
+-- try updating the cursor's current row
+create temp table forc_test as
+  select n as i, n as j from generate_series(1,10) n;
+create or replace function forc01() returns void as $$
+declare
+  c cursor for select * from forc_test;
+begin
+  for r in c loop
+    raise notice '%, %', r.i, r.j;
+    update forc_test set i = i * 100, j = r.j * 2 where current of c;
+  end loop;
+end;
+$$ language plpgsql;
+select forc01();
+NOTICE:  1, 1
+NOTICE:  2, 2
+NOTICE:  3, 3
+NOTICE:  4, 4
+NOTICE:  5, 5
+NOTICE:  6, 6
+NOTICE:  7, 7
+NOTICE:  8, 8
+NOTICE:  9, 9
+NOTICE:  10, 10
+ forc01 
+--------
+ 
+(1 row)
+
+select * from forc_test;
+  i   | j  
+------+----
+  100 |  2
+  200 |  4
+  300 |  6
+  400 |  8
+  500 | 10
+  600 | 12
+  700 | 14
+  800 | 16
+  900 | 18
+ 1000 | 20
+(10 rows)
+
+drop function forc01();
+-- fail because cursor has no query bound to it
+create or replace function forc_bad() returns void as $$
+declare
+  c refcursor;
+begin
+  for r in c loop
+    raise notice '%', r.i;
+  end loop;
+end;
+$$ language plpgsql;
+ERROR:  cursor FOR loop must use a bound cursor variable
+CONTEXT:  compile of PL/pgSQL function "forc_bad" near line 4

src/test/regress/sql/plpgsql.sql

@@ -2595,3 +2595,77 @@ end
 $$ language plpgsql;
 
 select exc_using(5, 'foobar');
+
+-- test FOR-over-cursor
+
+create or replace function forc01() returns void as $$
+declare
+  c cursor(r1 integer, r2 integer)
+       for select * from generate_series(r1,r2) i;
+  c2 cursor
+       for select * from generate_series(41,43) i;
+begin
+  for r in c(5,7) loop
+    raise notice '% from %', r.i, c;
+  end loop;
+  -- again, to test if cursor was closed properly
+  for r in c(9,10) loop
+    raise notice '% from %', r.i, c;
+  end loop;
+  -- and test a parameterless cursor
+  for r in c2 loop
+    raise notice '% from %', r.i, c2;
+  end loop;
+  -- and try it with a hand-assigned name
+  raise notice 'after loop, c2 = %', c2;
+  c2 := 'special_name';
+  for r in c2 loop
+    raise notice '% from %', r.i, c2;
+  end loop;
+  raise notice 'after loop, c2 = %', c2;
+  -- and try it with a generated name
+  -- (which we can't show in the output because it's variable)
+  c2 := null;
+  for r in c2 loop
+    raise notice '%', r.i;
+  end loop;
+  raise notice 'after loop, c2 = %', c2;
+  return;
+end;
+$$ language plpgsql;
+
+select forc01();
+
+-- try updating the cursor's current row
+
+create temp table forc_test as
+  select n as i, n as j from generate_series(1,10) n;
+
+create or replace function forc01() returns void as $$
+declare
+  c cursor for select * from forc_test;
+begin
+  for r in c loop
+    raise notice '%, %', r.i, r.j;
+    update forc_test set i = i * 100, j = r.j * 2 where current of c;
+  end loop;
+end;
+$$ language plpgsql;
+
+select forc01();
+
+select * from forc_test;
+
+drop function forc01();
+
+-- fail because cursor has no query bound to it
+
+create or replace function forc_bad() returns void as $$
+declare
+  c refcursor;
+begin
+  for r in c loop
+    raise notice '%', r.i;
+  end loop;
+end;
+$$ language plpgsql;