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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Warn when saving a pointer to an object with temporary lifetime"
href="https://bugs.llvm.org/show_bug.cgi?id=51002">51002</a>
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<th>Summary</th>
<td>Warn when saving a pointer to an object with temporary lifetime
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>josephcsible@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>Consider this C code:
typedef struct {
int x[1];
} foo;
foo f(void);
int g(void) {
int *p = f().x;
return *p;
}
The g() function is always UB, since the return value of f() has temporary
lifetime, so doing "return *p;" is dereferencing a pointer to an object whose
lifetime has ended. (This is the case both before and after C11's change to
temporary lifetime.) Since it's obvious at compile time that p can never be
used safely, we should have a warning for it, similar to how we have
-Wreturn-stack-address to catch mistakes like this function:
int *h(void) {
int x;
return &x;
}</pre>
</div>
</p>
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