[conv.lval] Add example of erroneous 'trap representation' being read

Author: Eisenwave

source/expressions.tex

@@ -678,6 +678,20 @@
 If the result is an erroneous value\iref{basic.indet} and
 the bits in the value representation are not valid for the object's type,
 the behavior is undefined.
+\begin{example}
+\begin{codeblock}
+int main() {
+  bool a;
+  bool b = a;
+}
+\end{codeblock}
+If the value of the byte(s) of the object representation of \tcode{a}
+are determined by the implementation so that the
+bits of the value representation of \tcode{a}
+correspond to \tcode{true} or \tcode{false},
+the lvalue-to-rvalue conversion during the initialization of \tcode{b}
+has erroneous behavior, and undefined behavior otherwise.
+\end{example}
 \end{itemize}
 
 \pnum