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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - class definition not allowed to change meaning of previously used name"
href="https://bugs.llvm.org/show_bug.cgi?id=51934">51934</a>
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<th>Summary</th>
<td>class definition not allowed to change meaning of previously used name
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>gonzalo.gadeschi@gmail.com
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<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>See <a href="http://eel.is/c++draft/class.member.lookup#6">http://eel.is/c++draft/class.member.lookup#6</a>
[class.member.lookup]/p6: "If it [the result of the search] differs from the
result of a search in T for N from immediately after the class-specifier of T,
the program is ill-formed, no diagnostic required." A class definition is not
allowed to change the meaning of a name that was already used earlier in the
class definition.
While no diagnostic is required, I think a quality implementation like clang
should produce a diagnostic here and reject this program since it is
ill-formed.
Example: <a href="https://gcc.godbolt.org/z/zG7Mn1Ebx">https://gcc.godbolt.org/z/zG7Mn1Ebx</a>
struct plus {
template<typename... Args>
using invoke = void;
};
template <typename Fn, typename... Args>
using invoke = typename Fn::template invoke<Args...>;
template <typename Fn>
struct compose
{
template <typename X, typename Y>
using F = invoke<Fn, X, Y>;
template <typename X>
using invoke = invoke<Fn, X, X>;
};
using Q = compose<plus>::F<int, int>;
Is accepted by clang.</pre>
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