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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - CFG shows temporary destructors in wrong order"
href="https://bugs.llvm.org/show_bug.cgi?id=46462">46462</a>
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<th>Summary</th>
<td>CFG shows temporary destructors in wrong order
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>10.0
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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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
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<th>Reporter</th>
<td>liblit@acm.org
</td>
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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
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=23651" name="attach_23651" title="source file demonstrating the problem">attachment 23651</a> <a href="attachment.cgi?id=23651&action=edit" title="source file demonstrating the problem">[details]</a></span>
source file demonstrating the problem
Temporaries are destroyed in reverse order of the completion of their
construction. In a comma expression with temporaries of type Alpha and Beta...
Alpha(), Beta();
...the Alpha temporary is constructed first and so should be destructed last.
However, a CFG dumped for this code shows the destructors running in the wrong
order:
[B1]
1: Alpha() (CXXConstructExpr, [B1.2], struct Alpha)
2: [B1.1] (BindTemporary)
3: Beta() (CXXConstructExpr, [B1.4], struct Beta)
4: [B1.3] (BindTemporary)
5: ... , [B1.4]
6: ~Alpha() (Temporary object destructor)
7: ~Beta() (Temporary object destructor)
Notice that ~Alpha() in statement 6 *precedes* ~Beta() in statement 7.
Bizarrely, by the time we reach bitcode or a runnable executable, the order is
correct. The actual generated code runs ~Beta() before ~Alpha() as it should.
But the CFG does not reflect this order for some reason.
Complete source file suitable for seeing the problem:
struct Alpha {
Alpha();
~Alpha();
};
struct Beta {
Beta();
~Beta();
};
void test() {
Alpha(), Beta();
}
Save this as "test.cc", then dump the CFG by running "clang++ -fsyntax-only
-Xclang -analyze -Xclang -analyzer-checker=debug.DumpCFG test.cc".</pre>
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