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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [-cxx-abi microsoft] Clang lays class out wrong when most derived class has a bitfield"
href="http://llvm.org/bugs/show_bug.cgi?id=18021">18021</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[-cxx-abi microsoft] Clang lays class out wrong when most derived class has a bitfield
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>LLVM Codegen
</td>
</tr>
<tr>
<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>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>consider:
#include <stddef.h>
#include <stdio.h>
#include <string.h>
char buffer[419430400];
inline void *operator new(size_t, void *pv) { return pv; }
struct ClassName00 {
long long ClassName00FieldName00;
ClassName00() {
printf("ClassName00FieldName00 : %llu\n", (unsigned long
long)((size_t)&ClassName00FieldName00 - (size_t)buffer));
}
};
struct ClassName02: public virtual ClassName00 {
long long ClassName02FieldName00;
ClassName02() {
printf("ClassName02FieldName00 : %llu\n", (unsigned long
long)((size_t)&ClassName02FieldName00 - (size_t)buffer));
}
};
struct ClassName03: public virtual ClassName02 {
int ClassName03FieldName3 : 1;
ClassName03() {
}
};
int main() {
memset(buffer, 0, sizeof(buffer));
new (buffer) ClassName03;
printf(" sizeof(ClassName03): %Iu\n", sizeof(ClassName03));
printf("__alignof(ClassName03): %Iu\n", __alignof(ClassName03));
memset(buffer, 0, sizeof(buffer));
}
clang gives us:
ClassName00FieldName00 : 16
ClassName02FieldName00 : 32
sizeof(ClassName03): 40
__alignof(ClassName03): 8
MSVC gives us:
ClassName00FieldName00 : 16
ClassName02FieldName00 : 40
sizeof(ClassName03): 48
__alignof(ClassName03): 8</pre>
</div>
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