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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - self reference function variable cannot deduce auto return type"
href="https://bugs.llvm.org/show_bug.cgi?id=43090">43090</a>
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<th>Summary</th>
<td>self reference function variable cannot deduce auto return type
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>release blocker
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C++17
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>adrianh.bsc@gmail.com
</td>
</tr>
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<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>This appears to be a bug. The following sample doesn't compile under LLVM but
does under gcc and msvc:
-----8<--------------------8<---------------
#define USE_TEMPLATE 0
#if USE_TEMPLATE
template <typename I>
constexpr auto fn(I i)
#else
auto fn = [](auto i) constexpr
#endif
{
if constexpr (i() == 0)
return fn([i]{return i() + 1;});
else
return 1;
};
int main()
{
return fn([]{ return 0;});
}
---------------->8-------------------->8----
It give the following error:
<source>:14:16: error: variable 'fn' declared with deduced type 'auto' cannot
appear in its own initializer
return fn([i]{return i() + 1;});
^
See <a href="https://godbolt.org/z/58VELd">https://godbolt.org/z/58VELd</a> for demo.</pre>
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