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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - VS C++ errors for compiler.h"
href="https://bugs.llvm.org/show_bug.cgi?id=40673">40673</a>
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<th>Summary</th>
<td>VS C++ errors for compiler.h
</td>
</tr>
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<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>6.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Support Libraries
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>hans.petter.dahle@hpdahle.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>When including the header file '\llvm\Support\Compiler.h',
Visual Studio's C++ compiler (used from Visual Studio Community 2017) complains
that there are 3 errors in this header file, on lines 127, 230, and 236.
The error message is:
E2512 the argument to a feature-test macro must be a simple identifier
The cause of these error messages is the use of "::" in the argument to
'__has_cpp_attribute'.
My proposal is to wrap each erroneous line and the line following it in a test
to check whether '_MSC_VER' is defined or not.
E.g. lines 127 and 128 which are
#elif __has_cpp_attribute(clang::warn_unused_result)
#define LLVM_NODISCARD [[clang::warn_unused_result]]
should be changed to
#elif !defined(_MSC_VER)
#if __has_cpp_attribute(clang::warn_unused_result)
#define LLVM_NODISCARD [[clang::warn_unused_result]]
#endif
This change fixes the error for me.</pre>
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