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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - empty range-for loop over map is not optimized away"
href="https://bugs.llvm.org/show_bug.cgi?id=46564">46564</a>
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<th>Summary</th>
<td>empty range-for loop over map is not optimized away
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Loop Optimizer
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>trass3r@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>#include <algorithm>
#include <map>
#include <string>
#include <vector>
using Map = std::map<int, std::vector<std::string>>;
void f1(const Map& m)
{
for (const auto& p : m)
{ (void)p; }
}
void f2(const Map& m)
{
std::for_each(m.begin(), m.end(), [](const std::pair<const int,
std::vector<std::string>>& p){
(void)p; });
}
Does work for f2. gcc eliminates both:
<a href="https://godbolt.org/z/E-LCJV">https://godbolt.org/z/E-LCJV</a></pre>
</div>
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