[llvm-dev] Commit 93af05e03e05d2f85b5a7e20ec3a3a543584d84f causes warning

[David Blaikie via llvm-dev]

Isn't there something weird with signedness of bitfields-of-enums in
particular in MSVC too?

On Fri, May 31, 2019 at 1:06 PM Reid Kleckner via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Generally it is preferable to store bitfields using plain integer types
> because MSVC has surprising behavior when packing bitfields of differing
> type. MSVC, for example, will not back this into one byte:
>   bool a : 1;
>   uint8_t b : 2;
>   bool c : 1;
> So, for LLVM or any other cross platform project, I recommend storing
> enums as some integer type, using the same type for all bitfields, and
> adding accessors to do the casts.
>
> On Fri, May 31, 2019 at 12:40 PM Lang Hames via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
>> Hi Denis,
>>
>> It is unfortunate that GCC has added such an aggressive warning with no
>> way to disable it. I would definitely make a comment on their bug tracker
>> that you have hit this.
>>
>> We could work around this by changing the field type to uint8_t and
>> adding casts, but I'm not sure whether we want to work around warnings in
>> other compilers as a matter of policy.
>>
>> Anyone else have thoughts on style here?
>>
>> Cheers,
>> Lang.
>>
>> On Fri, May 31, 2019 at 10:54 AM Bakhvalov, Denis <
>> denis.bakhvalov at intel.com> wrote:
>>
>>> Hello,
>>>
>>> After commit 93af05e03e05d2f85b5a7e20ec3a3a543584d84f we have new
>>> warning but only if compiled with GCC:
>>>
>>> In file included from
>>> /path/to/llvm/include/llvm/ExecutionEngine/Orc/ExecutionUtils.h:19:0,
>>>
>>>                  from
>>> /path/to/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h:23,
>>>
>>>                  from
>>> /path/to/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.cpp:9:
>>>
>>> /path/to/llvm/include/llvm/ExecutionEngine/Orc/Core.h:690:25: warning:
>>> ‘llvm::orc::JITDylib::SymbolTableEntry::State’ is too small to hold all
>>> values of ‘enum class llvm::orc::JITDylib::SymbolState’
>>>
>>>      SymbolState State : 6;
>>>
>>>
>>>
>>> There is no GCC option for disabling this warning:
>>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61414
>>>
>>> The issue is that now LLVM is not buildable with GCC and ‘-Werror’
>>> enabled.
>>>
>>>
>>>
>>> In addition, LLVM gcc-werror buildbot seems to be offline since May 9th:
>>> http://lab.llvm.org:8011/builders/ubuntu-gcc7.1-werror
>>>
>>>
>>>
>>> I understand that changing the code to satisfy GCC requirements might
>>> not be desired, but I think this is something that we should do.
>>>
>>>
>>>
>>> Best regards,
>>> Denis Bakhvalov.
>>>
>>>
>>>
>> _______________________________________________
>> LLVM Developers mailing list
>> llvm-dev at lists.llvm.org
>> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20190531/4553d70f/attachment.html>