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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [-cxx-abi microsoft] Layout involving pragma pack, declspec(align) and bitfields is wrong"
href="http://llvm.org/bugs/show_bug.cgi?id=18216">18216</a>
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<th>Summary</th>
<td>[-cxx-abi microsoft] Layout involving pragma pack, declspec(align) and bitfields is wrong
</td>
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<th>Product</th>
<td>clang
</td>
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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>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>LLVM Codegen
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>david.majnemer@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>consider:
#if defined(__clang__) || defined(__GNUC__)
typedef __SIZE_TYPE__ size_t;
#endif
extern "C" int printf(const char *fmt, ...);
inline void *operator new(size_t, void *pv) {}
#pragma pack(push, 4)
struct __declspec(align(256)) ClassName0 {
__declspec(align(512)) char : 3;
};
struct __declspec(align(2)) ClassName1 : public ClassName0 {
ClassName1() {}
};
struct ClassName2 : public ClassName0, public ClassName1 {};
struct ClassName3 : public ClassName0, public ClassName1 {};
static void test_layout(const char *class_name, size_t size_of_class,
size_t align_of_class) {
printf(" sizeof(%s): %Iu\n", class_name, size_of_class);
}
template <typename Class>
static void init_mem() {}
#define test(Class) \
init_mem<Class>(), test_layout(#Class, sizeof(Class), __alignof(Class))
int main() { test(ClassName0); }
msvc:
sizeof(ClassName0): 256
clang:
sizeof(ClassName0): 512</pre>
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