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<p class="MsoNormal"><span lang="EN-US">Hello Clang developers!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">We wanted to see if alpha.IdenticlExpression can be moved to core. It has been in StaticAnalyzer for a while. We have run alpha.IdenticalExpression on 451 projects in debian and evaluated the results.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Identical expression found 127 warnings - 117 true positives and 10 of them seem to be false positives. All 10 false positives are however due to code is hidden by preprocessor (macros and ifdefs) so we can’t do anything
about them. For example:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">#ifdef __clang__<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">#define MACRO(X)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">#endif<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">….<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> If (x > 10) {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> MACRO(10);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> } else {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> MACRO(1000);<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> }<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">=> 2.c:9:5: warning: true and false branches are identical<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">There was a warning that is not “perfect”. Reduced:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> if (x==10 || x == 20 || x == 10) <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">2.c:3:24: warning: identical expressions on both sides of logical operator<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> if (x==10 || x == 20 || x == 10)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> ~~~~~ ^ ~~~~~~~<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Maybe it could be clarified sometime.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Our conclusion is that this checker is ready for core.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Do you have some opinions?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Daniel Marjamäki<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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