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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">You cannot simply skip a redeclaration unless it is declared at same location.<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">For 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">namespace X { int a; }<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">// some other code<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">namespace X { int b; }<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">You cannot eliminate the second namespace, can you?<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">void foo () { using X:a; }<o:p></o:p></span></p>
<p class="MsoNormal"><a name="_MailEndCompose"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">void bar () { using X:a; }<o:p></o:p></span></a></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Also here, you cannot eliminate the second using-decl can you?<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">Looking into the code, it is not simple to introduce these checks, as there is no one place that will affect all Decls, and we will need to handle each Decl separately.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Can you think on a place where we can add this in AST?<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">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Amjad<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"><a name="_____replyseparator"></a><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> David Blaikie [mailto:dblaikie@gmail.com]
<br>
<b>Sent:</b> Tuesday, April 26, 2016 03:12<br>
<b>To:</b> reviews+D19468+public+d141c7248d054ca3@reviews.llvm.org; Aboud, Amjad <amjad.aboud@intel.com><br>
<b>Cc:</b> Duncan P. N. Exon Smith <dexonsmith@apple.com>; Adrian Prantl <aprantl@apple.com>; llvm-commits <llvm-commits@lists.llvm.org><br>
<b>Subject:</b> Re: [PATCH] D19468: Disallow duplication of imported entities (improved implementation)<o:p></o:p></span></p>
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<p class="MsoNormal">On Mon, Apr 25, 2016 at 2:25 PM, Amjad Aboud via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">aaboud added a comment.<br>
<br>
I am not much familiar with the AST part, but I assume there is reuse of previous generated DCL, even if it has same data.<o:p></o:p></p>
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<p class="MsoNormal"><br>
What if we filter by cases where the decl == the canonical decl, and skip any decl that's a redeclaration?<br>
<o:p></o:p></p>
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<p class="MsoNormal"><br>
Here is a small example that leads into duplication in AST DCLs.<br>
You may run the following command line:<br>
<br>
clang -cc1 -ast-dump -o - -O0 TestIM.cpp<br>
<br>
TestIM.cpp<br>
----------<br>
<br>
#include "TestIM.h"<br>
#include "TestIM.h"<br>
<br>
<br>
<br>
TestIM.h<br>
--------<br>
<br>
namespace X {<br>
typedef int MyINT_t;<br>
}<br>
<br>
namespace Y {<br>
using X::MyINT_t;<o:p></o:p></p>
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<p class="MsoNormal"> }<br>
<br>
<br>
<a href="http://reviews.llvm.org/D19468" target="_blank">http://reviews.llvm.org/D19468</a><br>
<br>
<br>
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