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<p class="MsoNormal">Hello,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am working on a custom attribute for an experimental project. I’ve just finally tracked down a problem where explicit template specializations have their attributes removed by Clang. I’m suspicious of the following function:
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:green">/// \brief Strips various properties off an implicit instantiation</span><span style="font-size:9.5pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:green">/// that has just been explicitly specialized.</span><span style="font-size:9.5pt;font-family:Consolas"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">static</span><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:blue">void</span> StripImplicitInstantiation(NamedDecl *D) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:green">// FIXME: "make check" is clean if the call to dropAttrs() is commented out.</span><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> D->dropAttrs();<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:blue">if</span> (FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> FD->setInlineSpecified(<span style="color:blue">false</span>);<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"> }<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">}<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">‘dropAttrs’ does exactly what you would expect: it removes the attributes from my explicit specialization. To me, this seems like incorrect behavior. Consider the following program:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">template</span><span style="font-size:9.5pt;font-family:Consolas"> <
<span style="color:blue">int</span> N ><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">int</span><span style="font-size:9.5pt;font-family:Consolas"> Test(<span style="color:blue">int</span> x) __attribute__((custom))<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">{<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:blue">return</span> x * N;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">}<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">template</span><span style="font-size:9.5pt;font-family:Consolas"> < ><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">int</span><span style="font-size:9.5pt;font-family:Consolas"> Test < 1 > (<span style="color:blue">int</span> x) __attribute__((custom))<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">{<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:blue">return</span> x;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">}<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When I debug a call to Test < 1 >, it behaves as if the program was written like so:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">template</span><span style="font-size:9.5pt;font-family:Consolas"> <
<span style="color:blue">int</span> N ><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">int</span><span style="font-size:9.5pt;font-family:Consolas"> Test(<span style="color:blue">int</span> x) __attribute__((custom))<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">{<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:blue">return</span> x * N;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">}<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">template</span><span style="font-size:9.5pt;font-family:Consolas"> < ><o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas;color:blue">int</span><span style="font-size:9.5pt;font-family:Consolas"> Test < 1 > (<span style="color:blue">int</span> x)
<span style="color:green">// custom attribute removed by StripImplicitInstantiation.<o:p></o:p></span></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">{<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">
<span style="color:blue">return</span> x;<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:9.5pt;font-family:Consolas">}<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I was hoping to understand the reasoning for this before I commented out dropAttrs here. The comment above dropAttrs seems to imply that it might not be fully correct. What is “make check”?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you for any insight into this issue!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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