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 441389745fe55e15a2d1915b093a831f859ba1bf..2f8468336f8603cd20ee4137bf15f61327b143d9 100644 (file)
--- a/src/pl/plpgsql/src/pl_exec.c
+++ b/src/pl/plpgsql/src/pl_exec.c
@@ -1418,17 +1418,9 @@ 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: