Message        <Context> accepting a compound literal as a constant
                is a language extension.  The compound literal will
                be treated as a cast expression.

 Description    A compound literal appears in a context where a
                constant expression is required.  The C standard does
                not list compound literals as a form of operand that
                is allowed in a constant expression, so using a
                compound literal in this context is not maximally
                portable.  The compiler will treat the compound
                literal as if it were a cast expression, which is a
                form of operand that the standard lists as being
                allowed in constant expressions.

 User Action    For maximum portability, replace the compound literal
                with a cast expression.