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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Use of uninitialized variable is not reported when followed by initialization in loop"
href="https://bugs.llvm.org/show_bug.cgi?id=49029">49029</a>
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<th>Summary</th>
<td>Use of uninitialized variable is not reported when followed by initialization in loop
</td>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>11.0
</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>
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<th>Component</th>
<td>C++
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>aa1ronham@gmail.com
</td>
</tr>
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
</td>
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<p>
<div>
<pre>The following code does not produce any warnings when compiled with 'clang++
weird.cpp -Wall'
```
int main() {
int x;
for (int i = 0; i < 10; i++) {
x += 1;
x = 0;
}
}
```
However, 'x' is uninitialized during the initial iteration through the loop. If
the 'x = 0;' line is removed:
```
int main() {
int x;
for (int i = 0; i < 10; i++) {
x += 1;
}
}
```
then a warning is produced when compiled with 'clang++ weird.cpp -Wall'
```
weird.cpp:4:9: warning: variable 'x' is uninitialized when used here
[-Wuninitialized]
x += 1;
^
weird.cpp:2:10: note: initialize the variable 'x' to silence this warning
int x;
^
= 0
1 warning generated.
```
The statement 'x = 0;' occurs after the uninitialized use of x, so it should
not cause the warning to be suppressed.</pre>
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</p>
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