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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Redefined classes are allowed"
href="https://bugs.llvm.org/show_bug.cgi?id=42339">42339</a>
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<th>Summary</th>
<td>Redefined classes are allowed
</td>
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<th>Product</th>
<td>clang
</td>
</tr>
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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>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
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<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>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>zhonghao@pku.org.cn
</td>
</tr>
<tr>
<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<pre>My clang is 9.0.0, and the code is:
template < class TP1 >
class MainClass {
public:
class A;
friend class B;
A a;
template < class TP2 > class B {};
class A {
template < class TP2 > friend class B;
};
};
int main(int argc, char *argv[]) {
MainClass<int> var;
}
clang accepts the code, but other compilers reject it, since B is redefined.
gcc:
<source>: In instantiation of 'class MainClass<int>::A':
<source>:9:5: required from 'class MainClass<int>'
<source>:22:18: required from here
<source>:13:11: error: 'template<class TP2> class MainClass<int>::B' redeclared
as different kind of entity
13 | class A {
| ^
<source>:7:16: note: previous declaration 'class B'
7 | friend class B;
| ^
Compiler returned: 1
icc:
<source>(15): error: "B" has already been declared in the current scope
template < class TP2 > friend class B;
^
detected during:
instantiation of class "MainClass<TP1>::A [with TP1=int]" at line 9
instantiation of class "MainClass<TP1> [with TP1=int]" at line 22
compilation aborted for <source> (code 2)
Compiler returned: 2</pre>
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