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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - clang silently ignores visibility attributes after implicit instantiation"
href="https://bugs.llvm.org/show_bug.cgi?id=34614">34614</a>
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<th>Summary</th>
<td>clang silently ignores visibility attributes after implicit instantiation
</td>
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>smeenai@fb.com
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<th>CC</th>
<td>compnerd@compnerd.org, dgregor@apple.com, eric@efcs.ca, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
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<pre>% cat repro.cc
template <class> class c { void f() {} };
template <> void c<int>::f() {}
template class __attribute__((__visibility__("default"))) c<int>;
% clang++ -std=c++11 -fvisibility=hidden -fvisibility-inlines-hidden \
-Wall -S -emit-llvm -o - | grep _ZN1cIiE1fEv
define hidden void @_ZN1cIiE1fEv(%class.c* %this) #0 align 2 {
The specialization on line 2 causes an implicit instantiation, which causes the
attributes on the explicit instantiation to be ignored. Ignoring the attributes
is a perfectly sane thing to do, but we should at least warn when we're doing
this, similar to gcc:
% g++ -std=c++11 -fsyntax-only repro.cc
repro.cc:3:59: warning: type attributes ignored after type is already defined
[-Wattributes]
template class __attribute__((__visibility__("default"))) c<int>;</pre>
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