[lustre-discuss] Compile a C++ app. using the Lustre API
François Tessier
ftessier at anl.gov
Tue Mar 21 12:53:14 PDT 2017
Hi Andreas,
I removed the "static_cast" and casted the __u16 to an enum
changelog_rec_flags as suggested. It seems to work (see patch attached).
Do you have a test to run to try this out?
Thanks!
François
On 03/19/2017 12:35 PM, Dilger, Andreas wrote:
> 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
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>> _______________________________________________
>>> lustre-discuss mailing list
>>> lustre-discuss at lists.lustre.org
>>> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
>> <lustre_user_cxx.patch>
>> _______________________________________________
>> lustre-discuss mailing list
>> lustre-discuss at lists.lustre.org
>> http://lists.lustre.org/listinfo.cgi/lustre-discuss-lustre.org
-------------- next part --------------
A non-text attachment was scrubbed...
Name: lustre_user_cxx.patch
Type: text/x-patch
Size: 2371 bytes
Desc: not available
URL: <http://lists.lustre.org/pipermail/lustre-discuss-lustre.org/attachments/20170321/9b91f4a2/attachment-0001.bin>
More information about the lustre-discuss
mailing list