Sophie: sbcl-1.0.31-1mdv2010.0 i586

sbcl-1.0.31-1mdv2010.0.i586.rpm

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<h5 class="subsubsection">4.1.3.2 The Original and Actual Source</h5>

<p><a name="index-Original-Source-39"></a><a name="index-Actual-Source-40"></a>
The <em>original source</em> displayed will almost always be a list. If
the actual source for an message is a symbol, the original source will
be the immediately enclosing evaluated list form. So even if the
offending symbol does appear in the original source, the compiler will
print the enclosing list and then print the symbol as the actual
source (as though the symbol were introduced by a macro.)

   <p>When the <em>actual source</em> is displayed (and is not a symbol), it
will always be code that resulted from the expansion of a macro or a
source-to-source compiler optimization. This is code that did not
appear in the original source program; it was introduced by the
compiler.

   <p>Keep in mind that when the compiler displays a source form in an
diagnostic message, it always displays the most specific (innermost)
responsible form. For example, compiling this function

<pre class="lisp">     (defun bar (x)
       (let (a)
         (declare (fixnum a))
         (setq a (foo x))
         a))
</pre>
   <p>gives this error message

<pre class="example">     ; file: /tmp/foo.lisp
     ; in: DEFUN BAR
     ;     (LET (A)
     ;     (DECLARE (FIXNUM A))
     ;     (SETQ A (FOO X))
     ;     A)
     ;
     ; caught WARNING:
     ;   Asserted type FIXNUM conflicts with derived type (VALUES NULL &amp;OPTIONAL).
</pre>
   <p>This message is not saying &ldquo;there is a problem somewhere in this
<code>let</code>&rdquo; &ndash; it is saying that there is a problem with the
<code>let</code> itself. In this example, the problem is that <code>a</code>'s
<code>nil</code> initial value is not a <code>fixnum</code>.

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