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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Unexpected internal linkage when using an alias to an private class"
href="https://bugs.llvm.org/show_bug.cgi?id=37279">37279</a>
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<th>Summary</th>
<td>Unexpected internal linkage when using an alias to an private class
</td>
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>unspecified
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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
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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>oliver@apple.com
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<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
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<p>
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<pre>I am not sure if clang's behaviour is wrong, but the behaviour is unexpected.
The basic issue is that I can have a public alias to a private type, but if the
alias appears in a method declaration the method is given internal linkage.
Here's a trivial example (compile with clang++ -c):
namespace Foo {
namespace {
struct _X {
int y;
};
}
using X = _X;
}
namespace Foo {
struct Bar {
X womp();
};
}
Foo::Bar *thing();
int main() {
thing()->womp();
return 0;
}
<a class="bz_bug_link
bz_status_NEW "
title="NEW - incorrect has internal linkage but is not defined [-Wundefined-internal] reported when a private class is used in a template"
href="show_bug.cgi?id=20296">Bug 20296</a> seems to be similar, but that seems to be related to class protection
rather than anonymous namespaces
Given that the X alias public it seems expected that the method should not
receive internal linkage. That would be my /expectation/, if the actual
specification is different, it would be great if the warning actually said why
a method got internal linkage.</pre>
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