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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Don't warn on -Wunused-const-variable when the variable comes from a template specialization in a macro."
href="https://llvm.org/bugs/show_bug.cgi?id=28878">28878</a>
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<th>Summary</th>
<td>Don't warn on -Wunused-const-variable when the variable comes from a template specialization in a macro.
</td>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</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>Frontend
</td>
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<th>Assignee</th>
<td>richard-llvm@metafoo.co.uk
</td>
</tr>
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<th>Reporter</th>
<td>zturner@google.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, rtrieu@google.com
</td>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>// Foo.h
template<typename T> struct Foo {};
#define SPECIALIZE_SOME_FOOS(_type) \
template <> struct Foo<std::vector<_type>> { \
static const bool F = true; \
}; \
template <> struct Foo<SmallVector<_type>> { \
static const bool B = true; \
};
// Foo.cpp
namespace {
typedef int MyType;
}
SPECIALIZE_SOME_FOOS(MyType)
These will warn on -Wunused-const-variable because the compiler can see all
possible uses MyType and determine that the template instantiation can never be
used. While technically correct, it might be a little too aggressive to warn
on this, especially when the template specializations come from a macro which
someone might design for simplicity to declare many possible specializations of
a class, of which a person might choose to rely on only a subset.</pre>
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