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</o:shapelayout></xml><![endif]--></head><body lang=HU link="#0563C1" vlink=purple style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>Thanks for your response David!<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>Actually, clang-tidy does something similar in the misc-redundant-expression check.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> ...<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> areEquivalentNameSpecifier(<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> cast<DependentScopeDeclRefExpr>(Left)->getQualifier(),<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> cast<DependentScopeDeclRefExpr>(Right)->getQualifier());<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>static bool areEquivalentNameSpecifier(const NestedNameSpecifier *Left,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> const NestedNameSpecifier *Right) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> llvm::FoldingSetNodeID LeftID, RightID;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> Left->Profile(LeftID);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> Right->Profile(RightID);<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'> return LeftID == RightID;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>}<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>But when I try to create a positive test case I fail.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>At line 7 in the next example, I don’t get a warning.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>It is because the folding set nodes (`LeftID` and `RightID`) are different.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>Just like the pointer values of `Left` and `Right`.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>I'm surprised about this, since I'm referring to the very same variable, thus I would expect the same pointer values.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>When I dump nested name specifiers I get the same string: “my_trait<char>::”<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>1 template <bool V> struct boolean_value {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>2 static constexpr bool value = V;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>3 };<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>4 template <typename T> struct my_trait : boolean_value<true> {};<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>5 bool respect_nested_name_specifiers(bool sink) {<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>6 sink = my_trait<char>::value || my_trait<int>::value; // no-warning, awesome<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>7 sink = my_trait<char>::value || my_trait<char>::value; // no warning for this either :(<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>8 return sink;<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>9 }<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'><br>How is it possible to have different NestedNameSpecifier pointers describing the same thing?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>Am I missing something?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>Thanks,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='mso-fareast-language:EN-US'>Balázs<br><br><o:p></o:p></span></p><div><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0cm 0cm 0cm'><p class=MsoNormal><b><span lang=EN-US>From:</span></b><span lang=EN-US> David Rector <davrecthreads@gmail.com> <br><b>Sent:</b> 2021. november 23., kedd 23:39<br><b>To:</b> Benics Balázs <benicsbalazs@gmail.com><br><b>Cc:</b> cfe-dev <cfe-dev@lists.llvm.org><br><b>Subject:</b> Re: [cfe-dev] Same AST for is_same<char, int>::value and is_same<char, long>::value<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Comparing the getQualifier()->getAsRecordDecl()s of the two DeclRefExprs should do it I think (untested). Careful though, NNS::getAsRecordDecl() crashes instead of returning null if the qualifier is e.g. a namespace, check its implem for the permissible kinds (or maybe better to add a getAsRecordDeclUnsafe() method).<o:p></o:p></p><div><div><p class=MsoNormal><br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal style='margin-bottom:12.0pt'>On Nov 23, 2021, at 11:03 AM, Benics Balázs via cfe-dev <<a href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a>> wrote:<o:p></o:p></p></blockquote></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><div><p class=MsoNormal> <o:p></o:p></p><div><p class=MsoNormal style='background:white'><span style='color:#212121'>(Resending from my personal email address)<o:p></o:p></span></p></div><div id=ms-outlook-mobile-signature><div><p class=MsoNormal><o:p> </o:p></p></div></div><div id=id-55f9e2ca-f8f6-43bd-a783-9b031c3c0c46><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif;color:black'><o:p> </o:p></span></p></div><div class=MsoNormal align=center style='text-align:center'><hr size=2 width="98%" align=center></div><div id=divRplyFwdMsg><p class=MsoNormal><strong><span style='font-family:"Calibri",sans-serif'>From:</span></strong> Balázs Benics <<a href="mailto:balazs.benics@sigmatechnology.se">balazs.benics@sigmatechnology.se</a>><br><strong><span style='font-family:"Calibri",sans-serif'>Sent:</span></strong> Tuesday, November 23, 2021, 14:45<br><strong><span style='font-family:"Calibri",sans-serif'>To:</span></strong> cfe-dev<br><strong><span style='font-family:"Calibri",sans-serif'>Subject:</span></strong> Same AST for is_same::value and is_same::value<br><br><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal><span lang=EN-US>I seek some advice on the following AST scenario.</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US><a href="https://godbolt.org/z/WcTeoGcbG">https://godbolt.org/z/WcTeoGcbG</a></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>1 #include <type_traits></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>2 using std::is_same;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>3 bool top() {</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>4 return is_same<char, int>::value || is_same<char, long>::value;</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>5 }</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>The `alpha.core.IdenticalExpr` static analyzer checker warns about that the two `..::value` are identical DeclRefExprs.</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>According to the AST, they are indeed identical:</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> BinaryOperator <col:10, col:60> 'bool' '||'</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> |-ImplicitCastExpr <col:10, col:30> 'bool':'bool' <LValueToRValue></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> | `-DeclRefExpr <col:10, col:30> 'const bool':'const bool' lvalue Var 0x563b67cde0a8 'value' 'const bool':'const bool'</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> `-ImplicitCastExpr <col:39, col:60> 'bool':'bool' <LValueToRValue></span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> `-DeclRefExpr <col:39, col:60> 'const bool':'const bool' lvalue Var 0x563b67cde0a8 'value' 'const bool':'const bool'</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Both of them refers to the same `VarDecl`, corresponding (probably) to the `std::false_type::value`.</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>How can I detect that even though the `values` look similar, they correspond to different template instances in that sense?</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>What do you suggest?</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>In the end, I want to suppress these reports in the static analyzer.</span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US> </span><o:p></o:p></p><p class=MsoNormal><span lang=EN-US>Balázs</span><o:p></o:p></p></div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>_______________________________________________<br>cfe-dev mailing list<br><a href="mailto:cfe-dev@lists.llvm.org">cfe-dev@lists.llvm.org</a><br><a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a><o:p></o:p></p></div></blockquote></div></div></body></html>