doc/guide/localhost/WarnUnusedAnomalies

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  26 <h1>WarnUnusedAnomalies</h1>
  27 </div>
  28 <div id="content">
  29 <div id="preamble">
  30 <div class="sectionbody">
  31 <div class="paragraph"><p>The <span class="monospaced">warnUnused</span> <a href="MLBasisAnnotations">MLBasis annotation</a> can be used
  32 to report unused identifiers.  This can be useful for catching bugs
  33 and for code maintenance (e.g., eliminating dead code).  However, the
  34 <span class="monospaced">warnUnused</span> annotation can sometimes behave in counter-intuitive
  35 ways.  This page gives some of the anomalies that have been reported.</p></div>
  36 <div class="ulist"><ul>
  37 <li>
  38 <p>
  39 Functions whose only uses are recursive uses within their bodies are
  40 not warned as unused:
  41 </p>
  42 <div class="listingblock">
  43 <div class="content"><div class="highlight"><pre><span class="k">local</span><span class="w"></span>
  44 <span class="k">fun</span><span class="w"> </span><span class="n">foo</span><span class="w"> </span><span class="p">()</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">foo</span><span class="w"> </span><span class="p">()</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
  45 <span class="k">val</span><span class="w"> </span><span class="n">bar</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="k">let</span><span class="w"> </span><span class="k">fun</span><span class="w"> </span><span class="n">baz</span><span class="w"> </span><span class="p">()</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">baz</span><span class="w"> </span><span class="p">()</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">unit</span><span class="w"> </span><span class="k">in</span><span class="w"> </span><span class="n">baz</span><span class="w"> </span><span class="k">end</span><span class="w"></span>
  46 <span class="k">in</span><span class="w"></span>
  47 <span class="k">end</span><span class="w"></span>
  48 </pre></div></div></div>
  49 <div class="listingblock">
  50 <div class="content monospaced">
  51 <pre>Warning: z.sml 3.5.
  52   Unused variable: bar.</pre>
  53 </div></div>
  54 </li>
  55 <li>
  56 <p>
  57 Components of actual functor argument that are necessary to match
  58 the functor argument signature but are unused in the body of the
  59 functor are warned as unused:
  60 </p>
  61 <div class="listingblock">
  62 <div class="content"><div class="highlight"><pre><span class="k">functor</span><span class="w"> </span><span class="n">Warning</span><span class="w"> </span><span class="p">(</span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">x</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="k">struct</span><span class="w"></span>
  63 <span class="w">   </span><span class="k">val</span><span class="w"> </span><span class="n">y</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">x</span><span class="w"></span>
  64 <span class="k">end</span><span class="w"></span>
  65 <span class="k">structure</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">Warning</span><span class="w"> </span><span class="p">(</span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">int</span><span class="w"> </span><span class="k">val</span><span class="w"> </span><span class="n">x</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="mi">1</span><span class="p">)</span><span class="w"></span>
  66 </pre></div></div></div>
  67 <div class="listingblock">
  68 <div class="content monospaced">
  69 <pre>Warning: z.sml 4.29.
  70   Unused type: t.</pre>
  71 </div></div>
  72 </li>
  73 <li>
  74 <p>
  75 No component of a functor result is warned as unused.  In the
  76 following, the only uses of <span class="monospaced">f2</span> are to match the functor argument
  77 signatures of <span class="monospaced">functor G</span> and <span class="monospaced">functor H</span> and there are no uses of
  78 <span class="monospaced">z</span>:
  79 </p>
  80 <div class="listingblock">
  81 <div class="content"><div class="highlight"><pre><span class="k">functor</span><span class="w"> </span><span class="n">F</span><span class="p">(</span><span class="k">structure</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="k">sig</span><span class="w"> </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="k">end</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="k">struct</span><span class="w"></span>
  82 <span class="w">   </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">X</span><span class="p">.</span><span class="n">t</span><span class="w"></span>
  83 <span class="w">   </span><span class="k">fun</span><span class="w"> </span><span class="n">f1</span><span class="w"> </span><span class="p">(_</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">X</span><span class="p">.</span><span class="n">t</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="p">()</span><span class="w"></span>
  84 <span class="w">   </span><span class="k">fun</span><span class="w"> </span><span class="n">f2</span><span class="w"> </span><span class="p">(_</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">X</span><span class="p">.</span><span class="n">t</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="p">()</span><span class="w"></span>
  85 <span class="w">   </span><span class="k">val</span><span class="w"> </span><span class="n">z</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="p">()</span><span class="w"></span>
  86 <span class="k">end</span><span class="w"></span>
  87 <span class="k">functor</span><span class="w"> </span><span class="n">G</span><span class="p">(</span><span class="k">structure</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="k">sig</span><span class="w"></span>
  88 <span class="w">                           </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
  89 <span class="w">                           </span><span class="k">val</span><span class="w"> </span><span class="n">f1</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
  90 <span class="w">                           </span><span class="k">val</span><span class="w"> </span><span class="n">f2</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
  91 <span class="w">                           </span><span class="k">val</span><span class="w"> </span><span class="n">z</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
  92 <span class="w">                        </span><span class="k">end</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="k">struct</span><span class="w"></span>
  93 <span class="w">   </span><span class="k">fun</span><span class="w"> </span><span class="n">g</span><span class="w"> </span><span class="p">(</span><span class="n">x</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span><span class="n">t</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span><span class="n">f1</span><span class="w"> </span><span class="n">x</span><span class="w"></span>
  94 <span class="k">end</span><span class="w"></span>
  95 <span class="k">functor</span><span class="w"> </span><span class="n">H</span><span class="p">(</span><span class="k">structure</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="k">sig</span><span class="w"></span>
  96 <span class="w">                           </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"></span>
  97 <span class="w">                           </span><span class="k">val</span><span class="w"> </span><span class="n">f1</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
  98 <span class="w">                           </span><span class="k">val</span><span class="w"> </span><span class="n">f2</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">-&gt;</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
  99 <span class="w">                           </span><span class="k">val</span><span class="w"> </span><span class="n">z</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">unit</span><span class="w"></span>
 100 <span class="w">                        </span><span class="k">end</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="k">struct</span><span class="w"></span>
 101 <span class="w">   </span><span class="k">fun</span><span class="w"> </span><span class="n">h</span><span class="w"> </span><span class="p">(</span><span class="n">x</span><span class="w"> </span><span class="p">:</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span><span class="n">t</span><span class="p">)</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">Y</span><span class="p">.</span><span class="n">f1</span><span class="w"> </span><span class="n">x</span><span class="w"></span>
 102 <span class="k">end</span><span class="w"></span>
 103 <span class="k">functor</span><span class="w"> </span><span class="n">Z</span><span class="p">()</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="k">struct</span><span class="w"></span>
 104 <span class="w">   </span><span class="k">structure</span><span class="w"> </span><span class="n">S</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">F</span><span class="p">(</span><span class="k">structure</span><span class="w"> </span><span class="n">X</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="k">struct</span><span class="w"> </span><span class="k">type</span><span class="w"> </span><span class="n">t</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">unit</span><span class="w"> </span><span class="k">end</span><span class="p">)</span><span class="w"></span>
 105 <span class="w">   </span><span class="k">structure</span><span class="w"> </span><span class="n">SG</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">G</span><span class="p">(</span><span class="k">structure</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">S</span><span class="p">)</span><span class="w"></span>
 106 <span class="w">   </span><span class="k">structure</span><span class="w"> </span><span class="n">SH</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">H</span><span class="p">(</span><span class="k">structure</span><span class="w"> </span><span class="n">Y</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">S</span><span class="p">)</span><span class="w"></span>
 107 <span class="k">end</span><span class="w"></span>
 108 <span class="k">structure</span><span class="w"> </span><span class="n">U</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">Z</span><span class="p">()</span><span class="w"></span>
 109 <span class="k">val</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">U</span><span class="p">.</span><span class="n">SG</span><span class="p">.</span><span class="n">g</span><span class="w"> </span><span class="p">()</span><span class="w"></span>
 110 <span class="k">val</span><span class="w"> </span><span class="p">_</span><span class="w"> </span><span class="p">=</span><span class="w"> </span><span class="n">U</span><span class="p">.</span><span class="n">SH</span><span class="p">.</span><span class="n">h</span><span class="w"> </span><span class="p">()</span><span class="w"></span>
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