[CMake] Where do add_dependencies() that are not defines go?

[Michael Wild]

Considering that doing something like this:

add_definitions(-m64)

is not a very good idea since it is very compiler/platform specific, you might want to attack the whole problem from a different angle:

if(CMAKE_COMPILER_IS_GNUC)
  if(CMAKE_SIZEOF_VOID_P EQUAL 8)
    set(_comp_flag -m64)
  else()
    set(_comp_flag -m32)
  endif()
elseif(...)
  ...
else()
  set(_comp_flag)
endif()
set(${PROJECT}_COMPILE_FLAGS "${_comp_flag}" CACHE STRING "Extra compile flags")
add_definitions(${${PROJECT}_COMPILE_FLAGS})


This way the user has still the opportunity to intervene and select different flags (or provide them if your CMakeLists.txt doesn't know how to handle this particular compiler).

HTH

Michael

On 29. Apr, 2010, at 9:41 , Marcel Loose wrote:

> Hi Luke,
> 
> A little digging revealed that you should use the property DEFINITIONS
> instead of COMPILE_DEFINITIONS, despite the fact that the manual says
> that DEFINITIONS is there for backward compatibility only. I noticed
> that that's the only property that contains your compile flag. Maybe
> someone from Kitware can comment on this?
> 
> Best regards,
> Marcel Loose.
> 
> On Wed, 2010-04-28 at 12:58 -0400, Luke Dalessandro wrote:
>> On Wed, Apr 28, 2010 at 12:04 PM, Marcel Loose <loose at astron.nl>
> wrote:
>>> Hi Luke,
>>> 
>>> Remember that the definitions you do with add_definitions() are
> scoped;
>>> i.e. you can only see them in the directory where you defined them
> and
>>> its sub-directories, but not its parent directories.
>>> 
>>> You should definitely do add_definitions("-m64") in your top-level
>>> directory.
>> 
>> I understand the scoping issue. The problem is that I don't know what
>> variable the non -D values are being placed in, so that I can recover
>> them in a custom build. They're not in any of the CMAKE_<LANG>_FLAGS,
>> nor are they in a file's COMPILE_FLAGS property. The -D values are
>> attached to the directory's COMPILE_DEFINITIONS, but the directory
>> doesn't have COMPILE_FLAGS.
>> 
>> They're not lost, because (say) -m64 does appear on the build line as
>> needed, I just don't know what variable they're being stored in.
>> 
>> Luke
>> 
>>> 
>>> Best regards,
>>> Marcel Loose.
>>> 
>>> On Wed, 2010-04-28 at 11:44 -0400, Luke Dalessandro wrote:
>>>> I meant add_definitions not dependencies. Sorry.
>>>> 
>>>> Luke
>>>> 
>>>> On Wed, Apr 28, 2010 at 11:39 AM, Luke Dalessandro
>>>> <ldalessandro at gmail.com> wrote:
>>>>> We sometimes use add_dependencies to add compile flags that
> aren't
>>>>> defines, e.g., -m64. I am trying to build an add_custom_command
> that
>>>>> needs access to these flags, but I can't seem to find them
> anywhere
>>> (I
>>>>> can get the dependencies from the directory properties).
>>>>> 
>>>>> Does anyone know where these other flag types are stored?
>>>>> 
>>>>> Thanks,
>>>>> Luke
>>>>> 
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