Must useless expressions be evaluated?

[vmicro1 at ucbtopaz.UUCP]

	I think useless expressions must be evaluated, simply because there is
no syntactic criterion to determine the uselessness of any expression. For
example,
	(i=j)+something()+k++;
is not syntactically different from
	(i=j)+1+k++;
but something() probably has side effects.