QIbaseResult: qWarning, when disallowed null parameter becomes zero

QIbaseResult turns null into zero when database field doesn't
accept a null argument.

This patch adds a warning in that case. It would be better to return
with an error, but that breaks existing behavior with code relying on
it.

Fixes: QTBUG-114683
Pick-to: 6.6 6.5
Change-Id: Ib50b7b6b4dd6c51489ba8b355f7baa8b1b14dc15
Reviewed-by: Ievgenii Meshcheriakov <ievgenii.meshcheriakov@qt.io>
Reviewed-by: Christian Ehrlicher <ch.ehrlicher@gmx.de>

src/plugins/sqldrivers/ibase/qsql_ibase.cpp

@@ -1051,6 +1051,9 @@ bool QIBaseResult::exec()
                 }
                 // a value of 0 means non-null.
                 *(d->inda->sqlvar[para].sqlind) = 0;
+            } else {
+                qWarning() << "QIBaseResult::exec: Null value replaced by zero for"_L1
+                           << d->inda->sqlvar[para].ownname;
             }
             switch(d->inda->sqlvar[para].sqltype & ~1) {
             case SQL_INT64: