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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - -Wimplicit-fallthrough needlessly warning about unreachable code"
href="https://bugs.llvm.org/show_bug.cgi?id=51094">51094</a>
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<th>Summary</th>
<td>-Wimplicit-fallthrough needlessly warning about unreachable code
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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>enhancement
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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>keescook@chromium.org
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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>There are some places in the kernel where the "fallthrough;" annotation is used
after a portion of code that may get elided at build time:
case 1:
if (something || !IS_ENALBED(CONFIG_SOMETHING))
return blah;
fallthrough;
case 2:
This looks like:
case 1:
fallthrough;
case 2:
And a warning is generated:
warning: fallthrough annotation in unreachable code [-Wimplicit-fallthrough]
But isn't a useful warning in this case, and should likely be silenced or
adjust to not warn where there was actually code there before getting elided.
At the least, this warning would be best moved to a separate flag so it can be
disabled on kernel builds (i.e. GCC does not warn about these cases).
Some specific examples:
<a href="https://github.com/ClangBuiltLinux/continuous-integration2/runs/3058126539?check_suite_focus=true#step:5:120">https://github.com/ClangBuiltLinux/continuous-integration2/runs/3058126539?check_suite_focus=true#step:5:120</a>
<a href="https://github.com/ClangBuiltLinux/continuous-integration2/runs/3058126329?check_suite_focus=true#step:5:92">https://github.com/ClangBuiltLinux/continuous-integration2/runs/3058126329?check_suite_focus=true#step:5:92</a></pre>
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