name conflict after upgrade to HEAD.

[Willem Jan Withagen]

On 25-8-2016 09:06, Dimitry Andric wrote:
> On 24 Aug 2016, at 16:30, Willem Jan Withagen <wjw at digiware.nl> wrote:
>>
>> On 24-8-2016 15:23, Dimitry Andric wrote:
> ...
>>> Can you show the full command line used to build the offending source
>>> file?  Usually this is caused by an incorrect include directory search
>>> order.  And most often, that is caused by build systems inserting
>>> -isystem into compile command lines.
>>
>> This is the full output of the failing compile
>>
>> --WjW
>>
>> [  3%] Building CXX object
>> src/CMakeFiles/common.dir/common/perf_counters.cc.o
>> cd /home/wjw/ceph/build/src && /usr/bin/CC
>> -DCEPH_LIBDIR=\"/usr/local/lib\"
>> -DCEPH_PKGLIBDIR=\"/usr/local/lib/ceph\"
>> -I/home/wjw/ceph/build/src/include -I/home/wjw/ceph/src
>> -I/usr/local/include -I/home/wjw/ceph/build/include
>> -I/home/wjw/ceph/src/xxHash  -Wall -Wtype-limits -Wignored-qualifiers
>> -Winit-self -Wpointer-arith -Werror=format-security -fno-strict-aliasing
>> -fsigned-char -Wno-inconsistent-missing-override -Wno-mismatched-tags
>> -Wno-unused-function -Wno-unused-local-typedef
>> -Wno-inconsistent-missing-override -Wno-unused-private-field
>> -Wno-varargs -Wno-gnu-designator -Wno-mismatched-tags
>> -Wno-missing-braces -Wno-parentheses -Wno-deprecated-register
>> -ftemplate-depth-1024 -Wno-invalid-offsetof -Wnon-virtual-dtor
>> -Wno-overloaded-virtual -fdiagnostics-color=auto
>> -I/usr/local/include/nss/nss -I/usr/local/include/nspr
>> -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc
>> -fno-builtin-free -O0 -g -fPIC   -DHAVE_CONFIG_H -D__CEPH__ -D_REENTRANT
>> -D_THREAD_SAFE -D__STDC_FORMAT_MACROS -std=c++11 -o
>> CMakeFiles/common.dir/common/perf_counters.cc.o -c
>> /home/wjw/ceph/src/common/perf_counters.cc
>> In file included from /home/wjw/ceph/src/common/perf_counters.cc:17:
>> In file included from /home/wjw/ceph/src/common/perf_counters.h:21:
>> In file included from /home/wjw/ceph/src/include/utime.h:18:
>> /usr/include/c++/v1/math.h:845:37: error: reference to 'log' is ambiguous
>> log(_A1 __lcpp_x) _NOEXCEPT {return log((double)__lcpp_x);}
>>                                    ^
>> /usr/include/c++/v1/math.h:845:1: note: candidate found by name lookup
>> is 'log'
>> log(_A1 __lcpp_x) _NOEXCEPT {return log((double)__lcpp_x);}
>> ^
>> /usr/include/c++/v1/math.h:839:46: note: candidate found by name lookup
>> is 'log'
>> inline _LIBCPP_INLINE_VISIBILITY long double log(long double __lcpp_x)
>> _NOEXCEPT {return logl(__lcpp_x);}
>>                                             ^
>> /usr/include/c++/v1/math.h:838:46: note: candidate found by name lookup
>> is 'log'
>> inline _LIBCPP_INLINE_VISIBILITY float       log(float __lcpp_x)
>> _NOEXCEPT       {return logf(__lcpp_x);}
>>                                             ^
>> /usr/include/math.h:247:8: note: candidate found by name lookup is 'log'
>> double  log(double);
>>        ^
>> /home/wjw/ceph/src/common/ceph_context.h:44:13: note: candidate found by
>> name lookup is 'ceph::log'
>>  namespace log {
>>            ^
> 
> 
> Okay, no -isystem options there.  So that's not it.  Now I'm assuming
> this is because the original .cc file includes <math.h>, which imports a
> global "log" symbol.  Can you try changing that include to <cmath>?
> However, this could require prefixing some math function calls with
> std::.

That did not work either.
Same stack of errors, only now "includes/utimes.h" calls <cmath> calls
math.h on the next include.

Problem is still with the inclusion of the std math stuff.
And yes,
namespace ceph{
  namespace log{ ... }
}

is included before this.

But I'd expect the ceph::log not to conflict with {std::}log.
Compiler however thinks otherwise.
Needless to say that GCC does not complain and "does the expected".
(I'm not going to say: ther right thing)

--WjW