<literal>import</literal> declaration
that does not explicitly list the entities brought into scope. For
example
+ </para>
<programlisting>
module M where
import X( f )
import Y
import qualified Z
p x = f x x
-<programlisting>
+</programlisting>
+ <para>
The <option>-fwarn-import-lists</option> flag will warn about the import
of <literal>Y</literal> but not <literal>X</literal>
If module <literal>Y</literal> is later changed to export (say) <literal>f</literal>,
ambiguous. No warning is produced for the import of <literal>Z</literal>
because extending <literal>Z</literal>'s exports would be unlikely to produce
ambiguity in <literal>M</literal>.
+ </para>
</listitem>
</varlistentry>
<para>We don't use a <option>-O*</option> flag for day-to-day
work. We use <option>-O</option> to get respectable speed;
e.g., when we want to measure something. When we want to go for
- broke, we tend to use <option>-O2 -fvia-C</option> (and we go for
+ broke, we tend to use <option>-O2</option> (and we go for
lots of coffee breaks).</para>
<para>The easiest way to see what <option>-O</option> (etc.)