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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>My eventual question:<o:p></o:p></p><p class=MsoNormal>What is the best way for analysis AST visitors to visit template instantiations?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Background:<o:p></o:p></p><p class=MsoNormal>I am working on a checker that will report about excessive padding. Basically, any place where padding could be reduced by reordering data members, I want to emit a report. This is different from –Wpadding because I don’t want to report on items where there isn’t a relatively easy fix.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The general way I’m implementing this is by using the check::ASTDecl<RecordDecl> visitor, returning early for some really troublesome cases, then using getASTRecordLayout. I then compare the actual size and padding against a computed optimal padding and size, and report when the observed padding doesn’t meet the optimal padding.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I started writing tests for this, and started to run into problems with C++ templates. Here is the most troublesome code test case I’ve hit so far:<o:p></o:p></p><p class=MsoNormal>template <typename T><o:p></o:p></p><p class=MsoNormal>struct Foo {<o:p></o:p></p><p class=MsoNormal> // expected-warning@+1{{Excessive padding in struct 'Foo<int>::Nested'}}<o:p></o:p></p><p class=MsoNormal> struct Nested { // doesn’t actually warn though…<o:p></o:p></p><p class=MsoNormal> char c1;<o:p></o:p></p><p class=MsoNormal> T t;<o:p></o:p></p><p class=MsoNormal> char c2;<o:p></o:p></p><p class=MsoNormal> };<o:p></o:p></p><p class=MsoNormal>};<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>struct Holder { //no-warning<o:p></o:p></p><p class=MsoNormal> Foo<int>::Nested t1;<o:p></o:p></p><p class=MsoNormal> Foo<char>::Nested t2;<o:p></o:p></p><p class=MsoNormal>};<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>It seems that by default, AnalysisConsumer doesn’t visit template instantiations. In fact, if I add “bool shouldVisitTemplateInstantiations() const { return true; }” to the AnalysisConsumer class, I get the reports I expect. Is there a better way for me to accomplish my goal? I don’t like the idea of turning on instantiation visitation for every checker just because my checker needs it.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Before I found AnalysisConsumer, I did make an attempt to walk the instantiations by visiting ClassTemplateDecl and iterating over specializations. That works ok if I don’t have nested Records, like I posted above. I hadn’t found the “right” way to recurse into the structure before finding shouldVisitTemplateInsantiations. Maybe a “better” approach is to basically copy RecursiveASTVisitor::TraverseClassInstantiation? I’m not sure if I’m comfortable duplicating that code, but if it’s the better option then I will.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks for the help,<o:p></o:p></p><p class=MsoNormal>Ben Craig<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>Employee of Qualcomm Innovation Center, Inc.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:10.0pt;font-family:"Courier New"'>Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>