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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Any regular expression should not match an empty sequence if match_not_null is specified"
href="http://llvm.org/bugs/show_bug.cgi?id=21597">21597</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Any regular expression should not match an empty sequence if match_not_null is specified
</td>
</tr>
<tr>
<th>Product</th>
<td>libc++
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>All Bugs
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>kariya_mitsuru@hotmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu, mclow.lists@gmail.com
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=13364" name="attach_13364" title="clang++ -v">attachment 13364</a> <a href="attachment.cgi?id=13364&action=edit" title="clang++ -v">[details]</a></span>
clang++ -v
The sample code below should output "not match" but it outputs "match:0, 0" if
it is compiled by clang 3.6.0.
====================================================================================================
#include <iostream>
#include <regex>
int main()
{
std::cmatch m;
auto result = std::regex_search("a", m, std::regex("b*"),
std::regex_constants::match_not_null);
if (result) {
std::cout << "match:" << m.position() << ", " << m.length() <<
std::endl;
} else {
std::cout << "not match" << std::endl;
}
}
====================================================================================================
cf. <a href="http://melpon.org/wandbox/permlink/TPxMmBQOGj7FsFMZ">http://melpon.org/wandbox/permlink/TPxMmBQOGj7FsFMZ</a>
According to C++11 standard 28.5.2[re.matchflag]/Table 139, "The expression
shall not match an empty sequence." if match_not_null is specified.
Note that the sample code of the Boost.regex version outputs "not match".
cf. <a href="http://melpon.org/wandbox/permlink/v1HhsIs8d2LrmUk9">http://melpon.org/wandbox/permlink/v1HhsIs8d2LrmUk9</a>
(Sorry, It is compiled by gcc for restriction of Wandbox.)</pre>
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