Fix GET DIAGNOSTICS for case of assignment to function's first variable.

An incorrect and entirely unnecessary "safety check" in exec_stmt_getdiag()
caused the code to treat an assignment to a variable with dno zero as a
no-op.  Unfortunately, that's a perfectly valid dno.  This has been broken
since GET DIAGNOSTICS was invented.  It's not terribly surprising that the
bug went unnoticed for so long, since in most cases you probably wouldn't
use the function's first-created variable (normally its first parameter)
as a GET DIAGNOSTICS target.  Nonetheless, it's broken.  Per bug #6551
from Adam Buraczewski.

diff --git a/src/pl/plpgsql/src/pl_exec.c b/src/pl/plpgsql/src/pl_exec.c
index 09c86aa4c676f93bae92fcad65fdb41f5c636379..a385b9a82a20ef1b6dbb83c35f8df8e286f24d59 100644 (file)
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -1447,17 +1447,9 @@ exec_stmt_getdiag(PLpgSQL_execstate *estate, PLpgSQL_stmt_getdiag *stmt)
        foreach(lc, stmt->diag_items)
        {
                PLpgSQL_diag_item *diag_item = (PLpgSQL_diag_item *) lfirst(lc);
-               PLpgSQL_datum *var;
+               PLpgSQL_datum *var = estate->datums[diag_item->target];
                bool            isnull = false;
 
-               if (diag_item->target <= 0)
-                       continue;
-
-               var = estate->datums[diag_item->target];
-
-               if (var == NULL)
-                       continue;
-
                switch (diag_item->kind)
                {
                        case PLPGSQL_GETDIAG_ROW_COUNT: