Spreadsheet: Use Base::fromStdString/toStdString.

src/Mod/Spreadsheet/App/Sheet.cpp

@@ -37,6 +37,7 @@
 #include <Base/Placement.h>
 #include <Base/Reader.h>
 #include <Base/Writer.h>
+#include <Base/Tools.h>
 #include "SpreadsheetExpression.h"
 #include "Sheet.h"
 #include "SheetObserver.h"
@@ -670,7 +671,7 @@ void Sheet::recomputeCell(CellAddress p)
     catch (const Base::Exception & e) {
         QString msg = QString::fromUtf8("ERR: %1").arg(QString::fromUtf8(e.what()));
 
-        setStringProperty(p, msg.toStdString());
+        setStringProperty(p, Base::Tools::toStdString(msg));
         if (cell)
             cell->setException(e.what());