Compiler Warning C0542
Message: Inheritance is not intended for the data type "UNION" <data type name>.
Possible error cause: A structured data type (DUT
) is derived from a UNION
by extending with EXTENDS
, or a UNION
is derived from a DUT
. This kind of derivation is not permitted. However, for reasons of compatibility only a warning is issued.
Example 490. Example of the error:
TYPE U_StringExt EXTENDS U_StringBase : UNION str10 : STRING(10); END_UNION END_TYPE
TYPE U_StringBase : UNION str20 : STRING(20); END_UNION END_TYPE
PROGRAM PLC_PRG VAR uStringExt : U_StringExt; END_VAR uStringExt.str20 := 'a234567890b234567890'; -> C0542