What every compiler writer should know about programmers [pdf]
What? &quot;tested and production&quot; programs might be conforming according to the C standard, but that&#x27;s only because it&#x27;s a largely useless term:  <i>[a] conforming program is one that is acceptable to a conforming implementation.</i> [C99, 4]<p>If the implementation is conforming (which might not be the case) and has accepted the program (which could be chock full of cruft), then the program is conforming. The &quot;conforming&quot; designation simply doesn&#x27;t assure us of any measure of quality, other than that the program isn&#x27;t so bad that it doesn&#x27;t compile and link (with that one toolchain which produced its executable).<p>If the program is tested and in production using a compiler that is operated in a nonconforming mode (often the default on many compilers), then acceptance of the program doesn&#x27;t speak to its conformance at all.<p>This kind of twaddle in the abstract is a very bad way to start out a paper. (And I&#x27;m one of the &quot;converted&quot; people, you don&#x27;t have to work hard to convince me about the dangers of optimizing based on &quot;no UB&quot; ssumptions, without a single diagnostic squawk.)