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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Non-static const array is wrongly shared among recursions"
href="http://llvm.org/bugs/show_bug.cgi?id=18538">18538</a>
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<th>Summary</th>
<td>Non-static const array is wrongly shared among recursions
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</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>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>k_satoda@f2.dion.ne.jp
</td>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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</tr></table>
<p>
<div>
<pre>The assertion in the following program should never fail because
variables with automatic storage duration in a function should be
created for each recursive invocation, and such distinct objects'
address should not compare equal.
#include <assert.h>
#include <stdio.h>
int f(const int* p)
{
const int c[] = {12345,56789};
assert(p != c);
if (p == 0) { return f(c); }
puts("Done.");
return 0;
}
int main()
{
f(0);
}
Clang 3.3 seems violating the rule and causes an assertion failure.
<a href="http://melpon.org/wandbox/permlink/tYmnEVjMNP33nYHr">http://melpon.org/wandbox/permlink/tYmnEVjMNP33nYHr</a>
<span class="quote">> prog.exe: prog.c:6: int f(const int *): Assertion `p != c' failed.</span >
I'm referring WG14 N1570.
<a href="http://www.open-std.org/jtc1/sc22/wg14/www/standards.html">http://www.open-std.org/jtc1/sc22/wg14/www/standards.html</a>
>From 6.2.4 p6:
<span class="quote">> For such an object that does not have a variable length array type, its
> lifetime extends from entry into the block with which it is associated
> until execution of that block ends in any way. (Entering an enclosed
> block or calling a function suspends, but does not end, execution of the
> current block.) If the block is entered recursively, a new instance of
> the object is created each time.</span >
6.5.9 p6
<span class="quote">> Two pointers compare equal if and only if both are null pointers, both
> are pointers to the same object ...</span >
If the variable is not an array, there seems no problem.
<a href="http://melpon.org/wandbox/permlink/uYeR8GbRvuQN3CMC">http://melpon.org/wandbox/permlink/uYeR8GbRvuQN3CMC</a></pre>
</div>
</p>
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