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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Valid combination of "constexpr", "[[unlikely]]" and switch statement leads to "error: no return statement in constexpr function""
href="https://bugs.llvm.org/show_bug.cgi?id=50641">50641</a>
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<th>Summary</th>
<td>Valid combination of "constexpr", "[[unlikely]]" and switch statement leads to "error: no return statement in constexpr function"
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>12.0
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<th>Hardware</th>
<td>All
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<th>OS</th>
<td>All
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>normal
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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>treh@think-cell.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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<p>
<div>
<pre>The following code fails to compile in clang++ 12
<a href="https://godbolt.org/z/eGM93Tqcr">https://godbolt.org/z/eGM93Tqcr</a>
constexpr
char Test(int n) {
switch( n )
[[unlikely]] default: {
case 0: return 'a';
case 1: return 'b';
}
}
with the message:
<source>:3:6: error: no return statement in constexpr function
Even if it seems odd at first sight, this is valid C++ and compiles on latest
gcc <a href="https://godbolt.org/z/8YGfM3dM8">https://godbolt.org/z/8YGfM3dM8</a>
and MSVC <a href="https://godbolt.org/z/MP7YaP5qv">https://godbolt.org/z/MP7YaP5qv</a>
It is actually part of our production codebase, used there to implement a
"switch_no_default"-macro that asserts if a value occurs that's not among the
"cases".</pre>
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