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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Clang 7.0.0 RC1 -fno-ms-compatibility rejects Windows.h"
href="https://bugs.llvm.org/show_bug.cgi?id=38478">38478</a>
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<th>Summary</th>
<td>Clang 7.0.0 RC1 -fno-ms-compatibility rejects Windows.h
</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>Windows NT
</td>
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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>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>sfinae@hotmail.com
</td>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>I use -fno-ms-compatibility to verify that MSVC's STL uses conformant code
whenever possible. Between Clang 6.0.0 and 7.0.0 RC1, this started rejecting
Windows.h due to nonconformant enumerators:
C:\Temp>type kitty.cpp
#include <Windows.h>
C:\Temp>clang-cl -m32 -v
clang version 7.0.0 (tags/RELEASE_700/rc1)
Target: i386-pc-windows-msvc
Thread model: posix
InstalledDir: S:\msvc\src\vctools\NonShip\ClangLLVM\bin
C:\Temp>clang-cl -m32 /EHsc /nologo /W4 /c -fno-ms-compatibility kitty.cpp
In file included from kitty.cpp:1:
In file included from
S:\msvc\src\ExternalApis\Windows\10\sdk\inc\Windows.h:173:
S:\msvc\src\ExternalApis\Windows\10\sdk\inc\wingdi.h(2819,5): error:
enumerator value is not representable in the
underlying type 'int'
DISPLAYCONFIG_OUTPUT_TECHNOLOGY_INTERNAL = 0x80000000,
^
[...]
I've reported this to the WinSDK team, but I still need to unblock my testing
in the meantime. Can some way be added to request the strictness of
-fno-ms-compatibility, but without rejecting Windows.h like this?
Possibilities:
* A fine-grained option, so I could compile with -fno-ms-compatibility
-fms-compatibility-enum-value to request strictness for everything except these
enum values.
* I observe that -Wmicrosoft contains the fine-grained warning
-Wmicrosoft-enum-value for this case. Instead of introducing a new fine-grained
option, if -fno-ms-compatibility -Wno-microsoft-enum-value avoided this error,
that would be equally good for me. Perhaps better, because then I could wrap
Windows.h in
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wmicrosoft-enum-value"
#pragma clang diagnostic pop
and retain the enum strictness for the rest of our code.
* Go back to doing whatever Clang 6 did, which was presumably to consider this
enum behavior part of ms-extensions instead of ms-compatibility (but allowing
-Wmicrosoft to warn about it).</pre>
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