<html>
<head>
<base href="http://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [-cxx-abi microsoft] clang doesn't layout derived class on top of empty virtual base class"
href="http://llvm.org/bugs/show_bug.cgi?id=17768">17768</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[-cxx-abi microsoft] clang doesn't layout derived class on top of empty virtual base class
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>All
</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>#include <stddef.h>
#include <stdio.h>
#include <string.h>
char buffer[419430400];
inline void *operator new(size_t, void *pv) { return pv; }
struct TypeName0 {
TypeName0() {
printf("TypeName0 (this): %llu\n", (unsigned long
long)((size_t)this - (size_t)buffer));
}
};
struct TypeName1: public TypeName0 {
char TypeName1FieldName5;
TypeName1() {
printf("TypeName1 (this): %llu\n", (unsigned long
long)((size_t)this - (size_t)buffer));
printf("TypeName1 (fiel): %llu\n", (unsigned long
long)((size_t)&TypeName1FieldName5 - (size_t)buffer));
}
};
struct TypeName2: public virtual TypeName0 {
int TypeName2FieldName0;
TypeName2() {
printf("TypeName2 (this): %llu\n", (unsigned long
long)((size_t)this - (size_t)buffer));
}
};
struct TypeName3: public virtual TypeName1, public virtual TypeName2 {
int TypeName3FieldName0;
TypeName3() {
printf("TypeName3 (this): %llu\n", (unsigned long
long)((size_t)this - (size_t)buffer));
printf("TypeName3 (fiel): %llu\n", (unsigned long
long)((size_t)&TypeName3FieldName0 - (size_t)buffer));
}
};
int main() {
memset(buffer, 0, sizeof(buffer));
new (buffer) TypeName3;
}
clang:
TypeName0 (this): 8
TypeName1 (this): 8
TypeName1 (fiel): 8
TypeName0 (this): 9
TypeName2 (this): 12
TypeName3 (this): 0
TypeName3 (fiel): 4
vs:
TypeName0 (this): 8
TypeName1 (this): 8
TypeName1 (fiel): 8
TypeName0 (this): 16
TypeName2 (this): 16
TypeName3 (this): 0
TypeName3 (fiel): 4</pre>
</div>
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