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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Crash with empty parameter pack on variadic concept as return type constraint"
href="https://bugs.llvm.org/show_bug.cgi?id=48617">48617</a>
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<th>Summary</th>
<td>Crash with empty parameter pack on variadic concept as return type constraint
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>trunk
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++2a
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>schottm@google.com
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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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<pre><a href="https://godbolt.org/z/6KE9ed">https://godbolt.org/z/6KE9ed</a>
If a constraint on a return type ends up being given zero parameters for its
parameter pack, clang blows up with a very confusing crash and no useful
diagnostic. In addition, in certain situations if you explicitly specialize the
function template before calling it again without explicit template arguments,
the second inferred call will compile but only if preceded by the first call
with explicit args. Unfortunately I do not have a minimal repro of this case
yet but it is the way I initially encountered this bug.</pre>
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