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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Unnecessary warning: "array subscript is of type 'char' [-Wchar-subscripts]" with constant char indexes"
href="http://llvm.org/bugs/show_bug.cgi?id=18389">18389</a>
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<th>Summary</th>
<td>Unnecessary warning: "array subscript is of type 'char' [-Wchar-subscripts]" with constant char indexes
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>unspecified
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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
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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>chris+llvm.org@qwirx.com
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<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>The following code for example generates the warning:
BackupQueries.cpp:2092:29: warning: array subscript is of type 'char'
[-Wchar-subscripts]
bool MachineReadable = opts['m'];
Because 'm' is in ASCII, and therefore a positive char value, on all platforms
that GCC and LLVM support and almost certainly on all platforms implementing
C++11, this warning seems unnecessary, and clearing it requires obfuscating the
code thus:
bool MachineReadable = opts[(unsigned char)'m'];
We could probably choose not to show this warning when the value of the index
is known by the compiler to be positive.</pre>
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