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diff --git a/docs/CodingStandards.html b/docs/CodingStandards.html index e3ec3ff136..416c29b7be 100644 --- a/docs/CodingStandards.html +++ b/docs/CodingStandards.html @@ -851,6 +851,38 @@ return 0; </pre> </div> +<p>Another issue is that values used only by assertions will produce an "unused + value" warning when assertions are disabled. For example, this code will warn: +</p> + +<div class="doc_code"> +<pre> + unsigned Size = V.size(); + assert(Size > 42 && "Vector smaller than it should be"); + + bool NewToSet = Myset.insert(Value); + assert(NewToSet && "The value shouldn't be in the set yet"); +</pre> +</div> + +<p>These are two interesting different cases: in the first case, the call to +V.size() is only useful for the assert, and we don't want it executed when +assertions are disabled. Code like this should move the call into the assert +itself. In the second case, the side effects of the call must happen whether +the assert is enabled or not. In this case, the value should be cast to void +to disable the warning. To be specific, it is preferred to write the code +like this:</p> + +<div class="doc_code"> +<pre> + assert(V.size() > 42 && "Vector smaller than it should be"); + + bool NewToSet = Myset.insert(Value); (void)NewToSet; + assert(NewToSet && "The value shouldn't be in the set yet"); +</pre> +</div> + + </div> <!-- _______________________________________________________________________ --> |