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<p class="MsoNormal"><span lang="EN-US">Hi there, I find a clang warning is suspicious.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Consider this code: <o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US"><o:p> </o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-US">template <typename T1> struct A {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> template <typename T2> struct B {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> template <typename T3> struct C {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> static void foo();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> };<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> };<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">};<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">template <> struct A<int> {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> template <typename T2> struct B {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> template <typename T3> struct C {<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> static void foo();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> };<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> };<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">};<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">template <> template <typename T3> struct A<int>::B<int>::C {
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> static void foo();<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">};<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Clang would emit a warning like “extraneous template parameter list in template specialization” at
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">template <> template <typename T3> struct A<int>::B<int>::C. I think the code should not trigger a warning here since the first template <> is applied to the explicit specialization of the nested class template B, not
to A as indicated by the “note” of clang diagnostic (since A has already had a declaration of an explicit specialization so the template <> for A could be omitted)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">After looking at the code, it looks like the problem is in SemaTemplate.cpp when iterating the nested types, the loop is terminated before it should be so the template header is never consumed. The attached patch fixes
this, with a test added. <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:10.5pt">Please review, thanks!<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Cheers<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">~Michael<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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