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<base href="https://bugs.llvm.org/">
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - MemorySanitizer: use-of-uninitialized-value in std::string s = "x"; std::strlen(s.c_str());"
href="https://bugs.llvm.org/show_bug.cgi?id=50114">50114</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>MemorySanitizer: use-of-uninitialized-value in std::string s = "x"; std::strlen(s.c_str());
</td>
</tr>
<tr>
<th>Product</th>
<td>libc++
</td>
</tr>
<tr>
<th>Version</th>
<td>10.0
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
<tr>
<th>OS</th>
<td>Windows NT
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>All Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>nok.raven@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
</td>
</tr></table>
<p>
<div>
<pre>#include <string>
int main()
{
std::string s = "x";
(void)std::strlen(s.c_str());
}
clang++-11 -fsanitize=memory -stdlib=libc++ -g z.cpp -o z && ./z
==63085==WARNING: MemorySanitizer: use-of-uninitialized-value
#0 0x49a3ab in std::__1::basic_string<char, std::__1::char_traits<char>,
std::__1::allocator<char> >::__get_pointer() const
/usr/lib/llvm-11/bin/../include/c++/v1/string:1517:17
#1 0x49a2b8 in std::__1::basic_string<char, std::__1::char_traits<char>,
std::__1::allocator<char> >::data() const
/usr/lib/llvm-11/bin/../include/c++/v1/string:1245:75
#2 0x499f10 in std::__1::basic_string<char, std::__1::char_traits<char>,
std::__1::allocator<char> >::c_str() const
/usr/lib/llvm-11/bin/../include/c++/v1/string:1243:55
#3 0x499d34 in main /home/user/z.cpp:6:25
#4 0x7f8a3bdb6cb1 in __libc_start_main csu/../csu/libc-start.c:314:16
#5 0x41d26d in _start (/home/user/z+0x41d26d)
SUMMARY: MemorySanitizer: use-of-uninitialized-value
/usr/lib/llvm-11/bin/../include/c++/v1/string:1517:17 in
std::__1::basic_string<char, std::__1::char_traits<char>,
std::__1::allocator<char> >::__get_pointer() const
Exiting
Clang/libc++ 10+ are affected
<a href="https://godbolt.org/z/h8Y5K1M9K">https://godbolt.org/z/h8Y5K1M9K</a></pre>
</div>
</p>
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