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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 - Default argument checking not performed after overload resolution with C linkage"
href="https://bugs.llvm.org/show_bug.cgi?id=38237">38237</a>
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<th>Summary</th>
<td>Default argument checking not performed after overload resolution with C linkage
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
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<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>Linux
</td>
</tr>
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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>C++
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>zhonghao@pku.org.cn
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>he following code is ill-formed according to the standard, but accepted by
clang++:
namespace A {
extern "C" void f(int = 5);
}
namespace B {
extern "C" void f(int = 4);
}
using A::f;
using B::f;
int main() {
f(3); //OK
f(); //ERROR
}
When a default argument is used as in the second call, it needs to be looked up
to make sure it isn't declared twice. If it is, then it's an error. clang++
will also accept the code whether the default arguments to f() are given the
same or different values.
Instead, g++ rejects the code:
code0.cpp:12:4: error: default argument mismatch in overload resolution
[-fpermissive]
f(); //ERROR
^
code0.cpp:2:18: note: candidate 1: 'void A::f(int = 5)'
extern "C" void f(int = 5);
^
code0.cpp:5:18: note: candidate 2: 'void B::f(int = 4)'
extern "C" void f(int = 4);
^</pre>
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</p>
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