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.

diff --git a/src/backend/executor/functions.c b/src/backend/executor/functions.c
index 4781bd903ab0b5b2e1f112c653847cf22e5602cb..1e1d450be57d2735a03f5b8197fed3d074bf18b0 100644 (file)
--- 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 1.113 2007/04/02 03:49:38 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/executor/functions.c,v 1.114 2007/04/02 18:49:29 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -849,9 +849,9 @@ ShutdownSQLFunction(Datum arg)
  * ANYELEMENT 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
@@ -864,7 +864,6 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
                                        JunkFilter **junkFilter)
 {
        Query      *parse;
-       bool            isSelect;
        List       *tlist;
        ListCell   *tlistitem;
        int                     tlistlen;
@@ -890,32 +889,30 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
        parse = (Query *) lfirst(list_tail(queryTreeList));
 
        /*
-        * Note: eventually replace this with QueryReturnsTuples?  We'd need a
-        * more general method of determining the output type, though.
-        */
-       isSelect = (parse->commandType == CMD_SELECT && parse->into == NULL);
-
-       /*
-        * 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.
+        *
+        * Note: eventually replace this test with QueryReturnsTuples?  We'd need
+        * a more general method of determining the output type, though.
         */
-       if (rettype == VOIDOID)
+       if (!(parse->commandType == CMD_SELECT && parse->into == NULL))
        {
-               if (isSelect)
+               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 (!isSelect)
-               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.
@@ -927,10 +924,11 @@ check_sql_fn_retval(Oid func_id, Oid rettype, List *queryTreeList,
 
        if (fn_typtype == TYPTYPE_BASE ||
                fn_typtype == TYPTYPE_DOMAIN ||
-               fn_typtype == TYPTYPE_ENUM)
+               fn_typtype == TYPTYPE_ENUM ||
+               rettype == VOIDOID)
        {
                /*
-                * 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.)
                 */