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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I discovered this starting from the following example<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">extern int &foo();<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">int &m([&]() { m = foo(); return m; }());<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">This should be also warned too.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> cfe-commits-bounces@cs.uiuc.edu [mailto:cfe-commits-bounces@cs.uiuc.edu]
<b>On Behalf Of </b>Richard Smith<br>
<b>Sent:</b> Friday, September 28, 2012 4:15 PM<br>
<b>To:</b> Jordan Rose; Richard Trieu<br>
<b>Cc:</b> llvm cfe<br>
<b>Subject:</b> Re: [cfe-commits] [Patch] Warn about self-init of refs using parenthesized initializers<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">I don't think the patch is right. My recollection of this class is (though perhaps Richard Trieu can correct me):<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">HandleExpr is intended to be called for the expression which is the top-level initializer of the declaration.<o:p></o:p></p>
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<p class="MsoNormal">HandleValue is intended to be called for an expression which is "used" (either directly in the initialization of the result, or as the operand of an lvalue-to-rvalue conversion).<o:p></o:p></p>
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<p class="MsoNormal">Visit* are called for all evaluated subexpressions (including ones we don't consider to be "used").<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">So... I think that we shouldn't be calling HandleExpr (nor HandleValue) from VisitParenListExpr, since it doesn't imply a use, in the required sense. I think the right way to deal with this is to add special cases for ParenListExpr and
InitListExpr to HandleExpr. We also need to decide whether to warn in these cases:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">int n(n); // Warn here, or is this treated like int n = n;?<o:p></o:p></p>
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<p class="MsoNormal">int n{n}; // Warn here, or is this treated like int n = n;?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">FWIW, it looks like we're missing an IgnoreParenCasts call from HandleExpr, and the IgnoreParenImpCasts call in HandleValue should be IgnoreParenCasts. We don't currently warn on cases like these, for instance:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">int &r = static_cast<int&>(r);<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">... nor ...<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">struct S {} s = static_cast<S&>(s);<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Sep 28, 2012 at 9:18 AM, Jordan Rose <<a href="mailto:jordan_rose@apple.com" target="_blank">jordan_rose@apple.com</a>> wrote:<o:p></o:p></p>
<p class="MsoNormal">This still doesn't handle C++11 initialization, does it?<br>
<br>
void g() {<br>
int &a{a};<br>
}<br>
<br>
Jordan<o:p></o:p></p>
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<p class="MsoNormal"><br>
<br>
On Sep 28, 2012, at 4:05 , Hans Wennborg <<a href="mailto:hans@chromium.org">hans@chromium.org</a>> wrote:<br>
<br>
> Hi,<br>
><br>
> As pointed out in Wei's email [1], Clang currently fails to warn about<br>
> self-initialized references when using parenthesized initializers:<br>
><br>
> void f() {<br>
> int &a(a);<br>
> }<br>
><br>
> The attached patch fixes this. Please take a look.<br>
><br>
> Thanks,<br>
> Hans<br>
><br>
> [1]. <a href="http://lists.cs.uiuc.edu/pipermail/cfe-dev/2012-September/024582.html" target="_blank">
http://lists.cs.uiuc.edu/pipermail/cfe-dev/2012-September/024582.html</a><o:p></o:p></p>
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<p class="MsoNormal">> <ref_self_init_parenthesized_initializers.patch>_______________________________________________<br>
> cfe-commits mailing list<br>
> <a href="mailto:cfe-commits@cs.uiuc.edu">cfe-commits@cs.uiuc.edu</a><br>
> <a href="http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits" target="_blank">
http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits</a><br>
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<p class="MsoNormal"><o:p> </o:p></p>
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