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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [coroutines] Incorrect warning about control reaching end of non-void generic coroutine lambda"
href="https://bugs.llvm.org/show_bug.cgi?id=43492">43492</a>
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<th>Summary</th>
<td>[coroutines] Incorrect warning about control reaching end of non-void generic coroutine lambda
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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
</td>
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
</td>
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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>lewissbaker@gmail.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>Clang trunk, 9.0 (but not 8.0 or earlier)
Compile options: -std=c++2a -fcoroutines-ts -stdlib=libc++ -Wreturn-type
See <a href="https://godbolt.org/z/pspDDo">https://godbolt.org/z/pspDDo</a>
Compiling the following code warns about control reaching the end of a non-void
lambda:
auto f = [](auto n) -> generator
{
co_yield n;
};
Results in the following warning:
<source>:43:5: warning: control reaches end of non-void lambda [-Wreturn-type]
};
Note that if the lambda is changed to be non-generic (ie. has argument 'int'
instead of 'auto') then the warning is not shown.
Execution running off the end of a coroutine should result in an implicit
'co_return;'.
It seems like the -Wreturn-type warning analyser is not aware of the fact that
this lambda is a coroutine and so follows different rules for determining
whether control runs off the end.</pre>
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