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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 --- - clang++ doesn't export operator delete with -flto"
href="http://llvm.org/bugs/show_bug.cgi?id=21001">21001</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>clang++ doesn't export operator delete with -flto
</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>
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<th>Component</th>
<td>C++
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>tavianator@tavianator.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>When using -flto, clang doesn't export a replacement operator delete, causing
shared libraries to call a different implementation than the main program.
Example:
$ cat main.cpp
#include <cstdlib>
#include <new>
#include <iostream>
void* operator new(std::size_t size) {
void* result = std::malloc(size);
if (result == nullptr) {
operator delete(result);
throw std::bad_alloc();
}
return result;
}
void operator delete(void* ptr) noexcept {
std::cout << "Deleting!" << std::endl;
std::free(ptr);
}
void deleteIt(int* ptr);
int main() {
deleteIt(new int);
return 0;
}
$ cat shared.cpp
void deleteIt(int* ptr) {
delete ptr;
}
$ clang++ -std=c++11 -g -O3 -flto -fuse-ld=gold -fPIC -shared shared.cpp -o
libshared.so
$ clang++ -std=c++11 -g -O3 -flto -fuse-ld=gold main.cpp -L. -lshared -o main
$ LD_LIBRARY_PATH=. ./main
$
(Note the missing "Deleting!" output.) objdump shows that the symbol isn't
exported:
$ objdump -T main | c++filt | grep operator
0000000000400e40 g DF .text 000000000000003a Base operator
new(unsigned long)
0000000000000000 DF *UND* 0000000000000000 Base operator
delete(void*)
The bug happens with C++98 mode too (with appropriate code changes), but the
C++14 operator delete(void*, std::size_t) works.
A workaround is to add __attribute__((used)) to operator delete. See
<a href="http://stackoverflow.com/q/25922895/502399">http://stackoverflow.com/q/25922895/502399</a>.</pre>
</div>
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