On 5. Jul, 2010, at 12:00 , Todd Gamblin wrote:
>
> On Jul 5, 2010, at 1:23 AM, Michael Wild wrote:
>
>>
>> On 5. Jul, 2010, at 7:46 , Todd Gamblin wrote:
>>
>>> The documentation here:
>>>
>>>
>>> http://*www.*cmake.org/cmake/help/cmake2.6docs.html#variable:CMAKE_COMPILER_IS_GNULANG
>>>
>>> is in conflict with the documentation here:
>>>
>>> http://*www.*cmake.org/Wiki/CMake_Useful_Variables
>>>
>>> And this thread (though it's from 2008) seems to imply that the second link
>>> above is right, even though the first is more current:
>>>
>>> http://*www.*mail-archive.com/cmake@cmake.org/msg16863.html
>>>
>>>
>>> I'm using CMake 2.8.2, and I'm noticing that CMAKE_COMPILER_IS_GNUC is
>>> empty, which conflicts with the latest documentation on the wiki. This
>>> makes it hard to do things like this:
>>>
>>>> for (lang C CXX Fortran)
>>>> if (CMAKE_COMPILER_IS_GNU${lang})
>>>> ...
>>>> endif()
>>>> endfor()
>>>
>>> Looking through the CMake source, it doesn't look like
>>> CMAKE_COMPILER_IS_GNUFortran is used anywhere. I tested it, and it looks
>>> like it's empty too. Would it be possible to add CMAKE_COMPILER_IS_GNUC
>>> and CMAKE_COMPILER_IS_GNUFortran so that they actually work? I think this
>>> would be more consistent than the current setup.
>>>
>>> These issues are coming up in the platform files I'm making for BlueGeneP.
>>> I think writing things like this would be easier if this were more
>>> consistent.
>>>
>>> -Todd
>>
>> The variables are called CMAKE_COMPILER_IS_GNUC, CMAKE_COMPILER_IS_GNUCXX
>> and CMAKE_COMPILER_IS_GNUG77 (the latter is admittedly weird)
>
> I don't think this is correct, at least not in the platform files in CMake
> 2.8.2. If I look at the value of CMAKE_COMPILER_IS_GNUC, it's empty. If I
> look at CMAKE_COMPILER_IS_GNUCC, it's getting set to what I'd expect. Is
> CMAKE_COMPILER_IS_GNUC set somewhere else, after the platform file gets
> included?
>
> G77 is weird, since as far as I can tell it's "Fortran" for all the other
> variables. Like I said, that really precludes you from doing something like
> this, especially if you try to set something inside the loop:
>
> for (lang C CXX Fortran)
> if (CMAKE_COMPILER_IS_GNU${lang})
> set(CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS "-shared")
> endif()
> endfor()
>
> Since now ${lang} needs to be something different in all those places.
Well, I got this information by simply grepping through the sources:
$ egrep -roh 'CMAKE_COMPILER_IS_GNU[A-Z0-9]*' Modules | sort -u
CMAKE_COMPILER_IS_GNUCC
CMAKE_COMPILER_IS_GNUCXX
CMAKE_COMPILER_IS_GNUG77
And you're right, it is CMAKE_COMPILER_IS_GNUCC and not CMAKE_COMPILER_IS_GNUC.
But that is kind of consistent with the variable names used in GNU Makefiles to
refer to the C, C++ and G77 compilers. If you are not happy with the names (for
the reason you posted above), you can use CMAKE_<LANG>_COMPILER_ID which should
be set to GNU if it is a GNU compiler:
for(lang C CXX Fortran)
if(CMAKE_${lang}_COMPILER_ID STREQUAL GNU)
set(CMAKE_SHARED_LIBRARY_CREATE_${lang}_FLAGS "-shared")
endif()
endforeach()
HTH
Michael
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