a <a href="#Conversions">conversion</a> with a result that is a constant, or
the result value of some built-in functions such as
<code>min</code> or <code>max</code> applied to constant arguments,
<code>unsafe.Sizeof</code> applied to <a href="#Package_unsafe">certain values</a>,
<code>cap</code> or <code>len</code> applied to
<a href="#Length_and_capacity">some expressions</a>,