[CMake] Checking function or symbol in namespace

[Michael Wild]

On 23. Jan, 2010, at 16:42 , Mateusz Loskot wrote:

> Jed Brown wrote:
>> On Thu, 21 Jan 2010 15:44:43 +0000, Mateusz Loskot <mateusz at loskot.net> wrote:
>>> Why it can not work, actually?
>> 
>> C++ does name mangling so it's difficult to determine what the symbol
>> actually is (you have to know about various classes and templates that
>> may be in scope), therefore the interface would look a bit different.
> 
> After some testing I did yesterday, I would add that one of the problems
> making it difficult to provide elegant macro checking C++ functions
> is the fact that in C++ functions can be overloaded.
> 
> I suppose that the only flexible, robust and also elegant way to provide
> cross-platform macros for detecting C++ (also with mixed in C99, TR1,
> C++0x, etc.) features is to develop one macro per feature (function,
> macro, etc.)
> 
> For instance,
> 
> 1) check_cxx_fabs - checks std::fabs in <cmath>, optionally falls back
> to ::fabs in <math.h> if a systems has problems with std:: (i.e. Visual
> C++ 6.0)
> 
> 2) check_cxx_isnan - tries if C++ impl. has C99 compatibility [1]
> additions, on some systems available as std::tr1::isnan on others as
> std::isnan, if fails, then falls back to system specific functions like
> _isnan() form Visual C++ or __inline_isnand from XCode, etc.
> 
> It would probably generate large number of small macros, but I can't see
> a more robust and flexible way to make such checks in reusable form.
> Perhaps it could make into the CMake distribution one day :-)
> 
> [1] http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2004/n1568.htm
> 
> Best regards,
> -- 
> Mateusz Loskot, http://mateusz.loskot.net
> Charter Member of OSGeo, http://osgeo.org


Don't think such a plethora of macros would be maintainable/manageable... Really just use CHECK_CXX_SOURCE_COMPILES.


Michael