Allow plpgsql functions to omit RETURN command when the function returns

output parameters or VOID or a set.  There seems no particular reason to
insist on a RETURN in these cases, since the function return value is
determined by other elements anyway.  Per recent discussion.

src/pl/plpgsql/src/gram.y

@@ -4,7 +4,7 @@
  *						  procedural language
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.68 2005/04/05 18:05:46 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/gram.y,v 1.69 2005/04/07 14:53:04 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -1071,7 +1071,7 @@ stmt_return		: K_RETURN lno
 						else if (plpgsql_curr_compile->fn_rettype == VOIDOID)
 						{
 							if (yylex() != ';')
-								yyerror("function returning void cannot specify RETURN expression");
+								yyerror("RETURN cannot have a parameter in function returning void");
 						}
 						else if (plpgsql_curr_compile->fn_retistuple)
 						{

src/pl/plpgsql/src/pl_comp.c

@@ -3,7 +3,7 @@
  *			  procedural language
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.86 2005/04/05 06:22:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_comp.c,v 1.87 2005/04/07 14:53:04 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -271,8 +271,8 @@ do_compile(FunctionCallInfo fcinfo,
 	int			parse_rc;
 	Oid			rettypeid;
 	int			numargs;
-	int			num_in_args;
-	int			num_out_args;
+	int			num_in_args = 0;
+	int			num_out_args = 0;
 	Oid		   *argtypes;
 	char	  **argnames;
 	char	   *argmodes;
@@ -374,7 +374,6 @@ do_compile(FunctionCallInfo fcinfo,
 			/*
 			 * Create the variables for the procedure's parameters.
 			 */
-			num_in_args = num_out_args = 0;
 			for (i = 0; i < numargs; i++)
 			{
 				char		buf[32];
@@ -641,12 +640,48 @@ do_compile(FunctionCallInfo fcinfo,
 	parse_rc = plpgsql_yyparse();
 	if (parse_rc != 0)
 		elog(ERROR, "plpgsql parser returned %d", parse_rc);
+	function->action = plpgsql_yylval.program;
 
 	plpgsql_scanner_finish();
 	pfree(proc_source);
 
 	/*
-	 * If that was successful, complete the function's info.
+	 * If it has OUT parameters or returns VOID or returns a set, we allow
+	 * control to fall off the end without an explicit RETURN statement.
+	 * The easiest way to implement this is to add a RETURN statement to the
+	 * end of the statement list during parsing.  However, if the outer block
+	 * has an EXCEPTION clause, we need to make a new outer block, since the
+	 * added RETURN shouldn't act like it is inside the EXCEPTION clause.
+	 */
+	if (num_out_args > 0 || function->fn_rettype == VOIDOID ||
+		function->fn_retset)
+	{
+		if (function->action->exceptions != NIL)
+		{
+			PLpgSQL_stmt_block *new;
+
+			new = palloc0(sizeof(PLpgSQL_stmt_block));
+			new->cmd_type	= PLPGSQL_STMT_BLOCK;
+			new->body		= list_make1(function->action);
+
+			function->action = new;
+		}
+		if (function->action->body == NIL ||
+			((PLpgSQL_stmt *) llast(function->action->body))->cmd_type != PLPGSQL_STMT_RETURN)
+		{
+			PLpgSQL_stmt_return *new;
+
+			new = palloc0(sizeof(PLpgSQL_stmt_return));
+			new->cmd_type = PLPGSQL_STMT_RETURN;
+			new->expr = NULL;
+			new->retvarno = function->out_param_varno;
+
+			function->action->body = lappend(function->action->body, new);
+		}
+	}
+
+	/*
+	 * Complete the function's info
 	 */
 	function->fn_nargs = procStruct->pronargs;
 	for (i = 0; i < function->fn_nargs; i++)
@@ -655,7 +690,6 @@ do_compile(FunctionCallInfo fcinfo,
 	function->datums = palloc(sizeof(PLpgSQL_datum *) * plpgsql_nDatums);
 	for (i = 0; i < plpgsql_nDatums; i++)
 		function->datums[i] = plpgsql_Datums[i];
-	function->action = plpgsql_yylval.program;
 
 	/* Debug dump for completed functions */
 	if (plpgsql_DumpExecTree)

src/pl/plpgsql/src/pl_exec.c

@@ -3,7 +3,7 @@
  *			  procedural language
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.134 2005/04/05 06:22:16 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/pl/plpgsql/src/pl_exec.c,v 1.135 2005/04/07 14:53:04 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -1691,12 +1691,18 @@ exec_stmt_return(PLpgSQL_execstate *estate, PLpgSQL_stmt_return *stmt)
 											&(estate->retisnull),
 											&(estate->rettype));
 		}
+
+		return PLPGSQL_RC_RETURN;
 	}
 
+	/*
+	 * Special hack for function returning VOID: instead of NULL, return a
+	 * non-null VOID value.  This is of dubious importance but is kept for
+	 * backwards compatibility.  Note that the only other way to get here
+	 * is to have written "RETURN NULL" in a function returning tuple.
+	 */
 	if (estate->fn_rettype == VOIDOID)
 	{
-		/* Special hack for function returning VOID */
-		Assert(stmt->retvarno < 0 && stmt->expr == NULL);
 		estate->retval = (Datum) 0;
 		estate->retisnull = false;
 		estate->rettype = VOIDOID;

src/test/regress/expected/plpgsql.out

@@ -1739,7 +1739,8 @@ SELECT * FROM test_ret_rec_dyn(5) AS (a int, b numeric, c text);
 (1 row)
 
 --
--- Test handling of OUT parameters, including polymorphic cases
+-- Test handling of OUT parameters, including polymorphic cases.
+-- Note that RETURN is optional with OUT params; we try both ways.
 --
 -- wrong way to do it:
 create function f1(in i int, out j int) returns int as $$
@@ -1769,7 +1770,6 @@ select * from f1(42);
 create or replace function f1(inout i int) as $$
 begin
   i := i+1;
-  return;
 end$$ language plpgsql;
 select f1(42);
  f1 
@@ -1805,7 +1805,6 @@ begin
   j := i;
   j := j+1;
   k := 'foo';
-  return;
 end$$ language plpgsql;
 select f1(42);
     f1    
@@ -1828,7 +1827,6 @@ begin
   j := j+1;
   k := 'foot';
   return next;
-  return;
 end$$ language plpgsql;
 select * from f1(42);
  j  |  k   
@@ -2358,6 +2356,27 @@ create function void_return_expr() returns void as $$
 begin
     return 5;
 end;$$ language plpgsql;
-ERROR:  function returning void cannot specify RETURN expression at or near "5" at character 72
+ERROR:  RETURN cannot have a parameter in function returning void at or near "5" at character 72
 LINE 3:     return 5;
                    ^
+-- VOID functions are allowed to omit RETURN
+create function void_return_expr() returns void as $$
+begin
+    perform 2+2;
+end;$$ language plpgsql;
+select void_return_expr();
+ void_return_expr 
+------------------
+ 
+(1 row)
+
+-- but ordinary functions are not
+create function missing_return_expr() returns int as $$
+begin
+    perform 2+2;
+end;$$ language plpgsql;
+select missing_return_expr();
+ERROR:  control reached end of function without RETURN
+CONTEXT:  PL/pgSQL function "missing_return_expr"
+drop function void_return_expr();
+drop function missing_return_expr();

src/test/regress/sql/plpgsql.sql

@@ -1561,7 +1561,8 @@ SELECT * FROM test_ret_rec_dyn(1500) AS (a int, b int, c int);
 SELECT * FROM test_ret_rec_dyn(5) AS (a int, b numeric, c text);
 
 --
--- Test handling of OUT parameters, including polymorphic cases
+-- Test handling of OUT parameters, including polymorphic cases.
+-- Note that RETURN is optional with OUT params; we try both ways.
 --
 
 -- wrong way to do it:
@@ -1582,7 +1583,6 @@ select * from f1(42);
 create or replace function f1(inout i int) as $$
 begin
   i := i+1;
-  return;
 end$$ language plpgsql;
 
 select f1(42);
@@ -1608,7 +1608,6 @@ begin
   j := i;
   j := j+1;
   k := 'foo';
-  return;
 end$$ language plpgsql;
 
 select f1(42);
@@ -1624,7 +1623,6 @@ begin
   j := j+1;
   k := 'foot';
   return next;
-  return;
 end$$ language plpgsql;
 
 select * from f1(42);
@@ -2001,3 +1999,22 @@ create function void_return_expr() returns void as $$
 begin
     return 5;
 end;$$ language plpgsql;
+
+-- VOID functions are allowed to omit RETURN
+create function void_return_expr() returns void as $$
+begin
+    perform 2+2;
+end;$$ language plpgsql;
+
+select void_return_expr();
+
+-- but ordinary functions are not
+create function missing_return_expr() returns int as $$
+begin
+    perform 2+2;
+end;$$ language plpgsql;
+
+select missing_return_expr();
+
+drop function void_return_expr();
+drop function missing_return_expr();