On Jul 5, 2010, at 4:25 AM, Michael Wild wrote:
>
> 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),
Yeah, still not happy. "Kind of consistent" is not kind of not the same as
consistent :-).
> 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()
But this is lovely. Thanks! This is probably a better way to do it anyway,
since what I really wanted to do was detect XL and default to GNU anyway.
-Todd
>
>
> HTH
>
> Michael
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