[lustre-discuss] Compile a C++ app. using the Lustre API
Dilger, Andreas
andreas.dilger at intel.com
Sun Mar 19 10:35:40 PDT 2017
Unfortunately, that is not something we could include into the C header, since it would break compilation.
What about just casting the __u16 to an enum changelog_rec_flags as needed, and declaring the local variables as the enum instead of an int?
Failing that, if you don't need the ChangeLog support, we could #ifdef out that section of the header when compiling with __cplusplus so that at least the rest of the header is usable.
Cheers, Andreas
> On Mar 16, 2017, at 09:17, François Tessier <ftessier at anl.gov> wrote:
>
> Here is the workaround I found (based on static_cast<>()):
>
> - make a local copy of lustre_user.h and lustreapi.h
> - apply the attached patch on lustre_user.h
> - add an include parameter in your CXXFLAGS pointing to these files
> - compile with CC
>
> It's clearly not the best solution but it's a working temporary band-aid...
>
> ++
>
> François
>
>
>> On 03/16/2017 07:44 AM, François Tessier wrote:
>>> On 03/15/2017 05:50 PM, Dilger, Andreas wrote:
>>>> On Mar 15, 2017, at 15:22, François Tessier <ftessier at anl.gov> wrote:
>>>> I get the same errors with g++ (v. 6.3). I can't find what kind of compiler flag I can use to be able to compile this. It clearly comes from how C++ deals with enum. The solutions I've found consist in "static_casting" the int values... Modifying my local version of lustre_user.h is probably not the best idea :-)
>>> Have you tried adding the standard wrappers at the start and end of the lustre_user.h header:
>>>
>>> #ifdef __cplusplus
>>> extern "C" {
>>> #endif
>>> :
>>> <rest of header>
>>> #ifdef __cplusplus
>>> }
>>> #endif
>>>
>>> I thought we had added those long ago, but I don't see them in the header today. If that fixes your problem, please file an LU ticket at https://jira.hpdd.intel.com/ (and ideally a patch at https://review.whamcloud.com/ too) and we can get this added to the header.
>>>
>>> In the meantime, you could also wrap your "#include <lustre/lustre_user.h>" similarly.
>> It doesn't fix the problem. I tried a more recent version of g++ or
>> several compiler options to force the use of C++11 [1] but with no success.
>>> Cheers, Andreas
>> Cheers,
>> François
>>
>> [1] http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2347.pdf
>>>>> On 03/15/2017 02:14 PM, Patrick Farrell wrote:
>>>>> It looks like your compiler is being fussier than the C compiler.
>>>>>
>>>>> Specifically, the problem appears to be with the enum type. The C compiler is happy to let pass using a short (cr_flags) where an enum is called for (argument to changelog_rec_offset). In C, I think an enum is an int (so passing in a short like this is always fine). I guess in C++ either enum is not an int, or it's just fussier.
>>>>>
>>>>> There might be a compiler flag to make it not error on this? I am not familiar with icpc, so I can't help with specifics.
>>>>>
>>>>> You might also try a different C++ compiler, to see if it has a different attitude towards that error.
>>>>>
>>>>> One further thought, though:
>>>>> This is a C header. Presumably, it is not intended to be included directly in a C++ project?
>>>>>
>>>>> - Patrick
>>>>> From: lustre-discuss <lustre-discuss-bounces at lists.lustre.org> on behalf of François Tessier <ftessier at anl.gov>
>>>>> Sent: Wednesday, March 15, 2017 2:00:31 PM
>>>>> To: lustre-discuss at lists.lustre.org
>>>>> Subject: [lustre-discuss] Compile a C++ app. using the Lustre API
>>>>>
>>>>> Hi All,
>>>>>
>>>>> I'm working on a piece of code using the Lustre API. To do so, I include
>>>>> lustreapi.h. When I compile my code with a C compiler (icc), everything
>>>>> is fine. However, when I compile it with a C++ compiler (icpc), I get
>>>>> these errors:
>>>>>
>>>>> ---------------------------------
>>>>>
>>>>> In file included from /usr/include/lustre/lustreapi.h(47),
>>>>> from topo.c(5):
>>>>> /usr/include/lustre/lustre_user.h(914): error: argument of type "__u16={unsigned short}" is incompatible with parameter of type "changelog_rec_flags"
>>>>> return changelog_rec_offset(rec->cr_flags);
>>>>> ^
>>>>>
>>>>> In file included from /usr/include/lustre/lustreapi.h(47),
>>>>> from topo.c(5):
>>>>> /usr/include/lustre/lustre_user.h(925): error: a value of type "int" cannot be used to initialize an entity of type "changelog_rec_flags"
>>>>> enum changelog_rec_flags crf = rec->cr_flags & CLF_VERSION;
>>>>> ^
>>>>>
>>>>> In file included from /usr/include/lustre/lustreapi.h(47),
>>>>> from topo.c(5):
>>>>> /usr/include/lustre/lustre_user.h(935): error: a value of type "int" cannot be used to initialize an entity of type "changelog_rec_flags"
>>>>> enum changelog_rec_flags crf = rec->cr_flags &
>>>>> ^
>>>>>
>>>>> In file included from /usr/include/lustre/lustreapi.h(47),
>>>>> from topo.c(5):
>>>>> /usr/include/lustre/lustre_user.h(945): error: argument of type "int" is incompatible with parameter of type "changelog_rec_flags"
>>>>> return (char *)rec + changelog_rec_offset(rec->cr_flags &
>>>>> ^
>>>>>
>>>>> In file included from /usr/include/lustre/lustreapi.h(47),
>>>>> from topo.c(5):
>>>>> /usr/include/lustre/lustre_user.h(986): error: this operation on an enumerated type requires an applicable user-defined operator function
>>>>> crf_wanted &= CLF_SUPPORTED;
>>>>> ^
>>>>>
>>>>> In file included from /usr/include/lustre/lustreapi.h(47),
>>>>> from topo.c(5):
>>>>> /usr/include/lustre/lustre_user.h(997): error: argument of type "int" is incompatible with parameter of type "changelog_rec_flags"
>>>>> changelog_rec_offset(crf_wanted & ~CLF_JOBID);
>>>>> ^
>>>>>
>>>>> In file included from /usr/include/lustre/lustreapi.h(47),
>>>>> from topo.c(5):
>>>>> /usr/include/lustre/lustre_user.h(999): error: argument of type "int" is incompatible with parameter of type "changelog_rec_flags"
>>>>> changelog_rec_offset(crf_wanted & ~(CLF_JOBID | CLF_RENAME));
>>>>> ^
>>>>>
>>>>> Makefile:10: recipe for target 'topo' failed
>>>>> make: *** [topo] Error 2
>>>>>
>>>>> ---------------------------------
>>>>>
>>>>> It's probably more a compiler issue than a Lustre one but a solution
>>>>> could help other users or Lustre developers.
>>>>>
>>>>> Any idea?
>>>>>
>>>>> Thanks,
>>>>>
>>>>> François
>>>>>
>>>>>
>>>>> --
>>>>> --
>>>>> François TESSIER, Ph.D.
>>>>> Postdoctoral Appointee
>>>>> Argonne National Laboratory
>>>>> LCF Division - Bldg 240, 4E 19
>>>>> Tel : +1 (630)-252-5068
>>>>> http://www.francoistessier.info
>>>>>
>>>>> _______________________________________________
>>>>> lustre-discuss mailing list
>>>>> lustre-discuss at lists.lustre.org
>>>>> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
>>>> _______________________________________________
>>>> lustre-discuss mailing list
>>>> lustre-discuss at lists.lustre.org
>>>> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
>>> Cheers, Andreas
>>> --
>>> Andreas Dilger
>>> Lustre Principal Architect
>>> Intel Corporation
>>>
>>>
>>>
>>>
>>>
>>>
>>>
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>
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