Fix check_sql_fn_retval to allow the case where a SQL function declared to

return void ends with a SELECT, if that SELECT has a single result that is
also of type void.  Without this, it's hard to write a void function that
calls another void function.  Per gripe from Peter.

Back-patch as far as 8.0.

1 files changed, 20 insertions, 22 deletions

diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
index 9f3a85dbf85..ec6ede2a544 100644
--- a/src/backend/executor/functions.c
+++ b/src/backend/executor/functions.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.91.4.3 2007/02/02 00:03:44 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.91.4.4 2007/04/02 18:49:49 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -848,9 +848,9 @@ ShutdownSQLFunction(Datum arg)
  * as rettype.  (This means we can't check the type during function definition
  * of a polymorphic function.)
  *
- * The return value is true if the function returns the entire tuple result
- * of its final SELECT, and false otherwise.  Note that because we allow
- * "SELECT rowtype_expression", this may be false even when the declared
+ * This function returns true if the sql function returns the entire tuple
+ * result of its final SELECT, and false otherwise.  Note that because we
+ * allow "SELECT rowtype_expression", this may be false even when the declared
  * function return type is a rowtype.
  *
  * If junkFilter isn't NULL, then *junkFilter is set to a JunkFilter defined
@@ -863,7 +863,6 @@ check_sql_fn_retval(Oid rettype, char fn_typtype, List *queryTreeList,
 					JunkFilter **junkFilter)
 {
 	Query	   *parse;
-	int			cmd;
 	List	   *tlist;
 	ListCell   *tlistitem;
 	int			tlistlen;
@@ -892,46 +891,45 @@ check_sql_fn_retval(Oid rettype, char fn_typtype, List *queryTreeList,
 	/* find the final query */
 	parse = (Query *) lfirst(list_tail(queryTreeList));
 
-	cmd = parse->commandType;
-	tlist = parse->targetList;
-
 	/*
-	 * The last query must be a SELECT if and only if return type isn't
-	 * VOID.
+	 * If the last query isn't a SELECT, the return type must be VOID.
 	 */
-	if (rettype == VOIDOID)
+	if (!(parse->commandType == CMD_SELECT && parse->into == NULL))
 	{
-		if (cmd == CMD_SELECT)
+		if (rettype != VOIDOID)
 			ereport(ERROR,
 					(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
 					 errmsg("return type mismatch in function declared to return %s",
 							format_type_be(rettype)),
-					 errdetail("Function's final statement must not be a SELECT.")));
+			 errdetail("Function's final statement must be a SELECT.")));
 		return false;
 	}
 
-	/* by here, the function is declared to return some type */
-	if (cmd != CMD_SELECT)
-		ereport(ERROR,
-				(errcode(ERRCODE_INVALID_FUNCTION_DEFINITION),
-		 errmsg("return type mismatch in function declared to return %s",
-				format_type_be(rettype)),
-			 errdetail("Function's final statement must be a SELECT.")));
+	/*
+	 * OK, it's a SELECT, so it must return something matching the declared
+	 * type.  (We used to insist that the declared type not be VOID in this
+	 * case, but that makes it hard to write a void function that exits
+	 * after calling another void function.  Instead, we insist that the
+	 * SELECT return void ... so void is treated as if it were a scalar type
+	 * below.)
+	 */
 
 	/*
 	 * Count the non-junk entries in the result targetlist.
 	 */
+	tlist = parse->targetList;
 	tlistlen = ExecCleanTargetListLength(tlist);
 
 	typerelid = typeidTypeRelid(rettype);
 
-	if (fn_typtype == 'b' || fn_typtype == 'd')
+	if (fn_typtype == 'b' || fn_typtype == 'd' ||
+		rettype == VOIDOID)
 	{
 		/* Shouldn't have a typerelid */
 		Assert(typerelid == InvalidOid);
 
 		/*
-		 * For base-type returns, the target list should have exactly one
+		 * For scalar-type returns, the target list should have exactly one
 		 * entry, and its type should agree with what the user declared.
 		 * (As of Postgres 7.2, we accept binary-compatible types too.)
 		 */