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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Passing multiple optimization level options (e.g., /O1 /O2) to clang-cl causes "argument unused" warning"
href="https://bugs.llvm.org/show_bug.cgi?id=34809">34809</a>
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<th>Summary</th>
<td>Passing multiple optimization level options (e.g., /O1 /O2) to clang-cl causes "argument unused" warning
</td>
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<th>Product</th>
<td>clang
</td>
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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>All
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Driver
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>dcower@google.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<pre>I am using trunk r314281. I would expect passing multiple /O<value> option to
cause the driver to use the final one passed (i.e., the behavior seen with
normal clang and multiple -O<value> options).
$ cat a.cc
int main() { return 0; }
$ clang-cl -c /O1 a.cc
<works fine -- no output>
$ clang-cl -c /O1 /O1 a.cc
clang-cl: warning: argument unused during compilation: '/O1'
[-Wunused-command-line-argument]
$ clang-cl -c /O1 /O2 a.cc
clang-cl: warning: argument unused during compilation: '/O1'
[-Wunused-command-line-argument]
$ clang-cl -c /O2 /O1 a.cc
clang-cl: warning: argument unused during compilation: '/O2'
[-Wunused-command-line-argument</pre>
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