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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - False positives in core.NullDereference on non_odr_use_constant DeclRefExpr to non-capture"
href="https://bugs.llvm.org/show_bug.cgi?id=46991">46991</a>
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<th>Summary</th>
<td>False positives in core.NullDereference on non_odr_use_constant DeclRefExpr to non-capture
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>All
</td>
</tr>
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<th>OS</th>
<td>All
</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>
</tr>
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<th>Component</th>
<td>Static Analyzer
</td>
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<th>Assignee</th>
<td>dcoughlin@apple.com
</td>
</tr>
<tr>
<th>Reporter</th>
<td>aaronpuchert@alice-dsl.net
</td>
</tr>
<tr>
<th>CC</th>
<td>dcoughlin@apple.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>On the following code:
void foo(int v);
constexpr int VAL = 1;
void bar()
{
const int& val = VAL;
[]() {
foo(val);
}();
}
the static analyzer warns
<source>:7:13: warning: Dereference of undefined pointer value
[core.NullDereference]
foo(val);
^
<source>:6:5: note: Uninitialized value stored to 'val'
[]() {
^~~~~~
<source>:6:5: note: Calling 'operator()'
[]() {
^~~~~~
<source>:7:13: note: Dereference of undefined pointer value
foo(val);
^~~
I think that's wrong, val has an initializer expression. Note that the
DeclRefExpr referring to val is marked as non_odr_use_constant, and val doesn't
need to be captured. Adding an explicit capture fixes the Static Analyzer issue
but raises a regular Clang warning:
<source>:6:6: warning: lambda capture 'val' is not required to be captured for
this use [-Wunused-lambda-capture]
[val]() {
^~~
or
<source>:6:7: warning: lambda capture 'val' is not required to be captured for
this use [-Wunused-lambda-capture]
[&val]() {
~^~~
Using a capture-default expression, i.e. [=] or [&], does not fix the issue.</pre>
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