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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Template instantiation with user-defined type generates hidden symbol when building a shared library from a .o with -fvisibility=hidden"
href="http://llvm.org/bugs/show_bug.cgi?id=16937">16937</a>
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<th>Summary</th>
<td>Template instantiation with user-defined type generates hidden symbol when building a shared library from a .o with -fvisibility=hidden
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>3.3
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>FreeBSD
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C++
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>rakuco@FreeBSD.org
</td>
</tr>
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<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=11070" name="attach_11070" title="Reduction + Makefile that calls nm.">attachment 11070</a> <a href="attachment.cgi?id=11070&action=edit" title="Reduction + Makefile that calls nm.">[details]</a></span>
Reduction + Makefile that calls nm.
(Sorry if the title sounded unclear)
Consider the following:
struct __attribute__((visibility("default"))) Foo {
template<typename T> void f(const T&) {}
};
struct SomeType {};
template void Foo::f<SomeType>(const SomeType&);
So if I have a class with default visibility and a template method that has an
instantiation with a user-defined type, the .o file generated with "clang++ -c
-fvisibility=hidden" will generate _ZN3Foo1fI8SomeTypeEEvRKT_ as a global weak
symbol, but when using that .o to generate a shared library, the resulting .so
will have _ZN3Foo1fI8SomeTypeEEvRKT_ as a local symbol in the text section, as
if the __attribute__ marker in the class had been discarded.
Generating the .so directly from the .cpp file produces a shared library with
_ZN3Foo1fI8SomeTypeEEvRKT_ as a global weak symbol, as will instantiating the
template method with a type such as int.
GCC makes _ZN3Foo1fI8SomeTypeEEvRKT_ a global weak symbol in both the .o and
the .so.</pre>
</div>
</p>
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