[CMake] Changing definitions at compile time

[Michael Wild]

On 06/14/2011 09:12 PM, Andreas Naumann wrote:
> Am 14.06.2011 19:26, schrieb Michael Wild:
>> On 06/14/2011 07:12 PM, Kfir Lavi wrote:
>>   
>>>
>>> On Tue, Jun 14, 2011 at 8:04 PM, Andreas Naumann
>>> <Andreas-Naumann at gmx.net<mailto:Andreas-Naumann at gmx.net>>  wrote:
>>>
>>>      Am 14.06.2011 18:12, schrieb Kfir Lavi:
>>>     
>>>>      Hi,
>>>>      I need to compile the code twice. Once with -DA and once with -DB
>>>>      My code look like this:
>>>>      add_definitions(-DA)
>>>>      add_library(${mylib_A} SHARED ${myfiles})
>>>>      remove_definitions(-DA)
>>>>
>>>>      add_definitions(-DB)
>>>>      add_library(${lib_B} SHARED ${myfiles})
>>>>      remove_definitions(-DB)
>>>>
>>>>      What cmake does is to define A and then remove it, so in compile
>>>>      time, there
>>>>      is now definition of A or B.
>>>>
>>>>      How do I tell cmake that the remove needs to  be in compile time?
>>>>
>>>>      Regards,
>>>>      Kfir
>>>>        
>>>      You want to create two libraries A and B from the same sourcefiles
>>>      ${myfiles}. The first one have to be compiled with -DA and the
>>>      second one with -DB, haven't it?
>>>
>>>      So you could simply set the COMPILE_FLAGS property with
>>>      add_library(A ${myfiles})
>>>      add_library(B ${myfiles})
>>>
>>>      set_target_properties(A PROPERTIES COMPILE_FLAGS "-DA")
>>>      set_target_properties(B PROPERTIES COMPILE_FLAGS "-DB")
>>>
>>>      Regards,
>>>      Andreas
>>>
>>>
>>> Thanks,
>>> This solved my problems.
>>>
>>> Again thanks,
>>> Kfir
>>>      
>> Except that COMPILE_FLAGS is the wrong property. You should use
>> COMPILE_DEFINITIONS without the -D prefix.
>>
>> Michael
>>
>>    
> correct me, if I am wrong, but at
> http://www.cmake.org/cmake/help/cmake-2-8-docs.html#command:set_target_properties
> 
> there is no property "COMPILE_DEFINITIONS".
> 
> If I search through the documentation, I get to the target properties.
> 
> It seems to me, that COMPILE_DEFINITIONS can set only preprocessor
> definitions like -DVAR=VALUE with
> set_target_properties(targ PROPERTIES COMPILE_DEFINITIONS "VAR=VALUE").
> But if I have a special compiler flag like
> -flag:flag_value
> I should use
> set_target_properties(targ PROPERTIES COMPILE_FLAGS "-flag:flag_value")
> 
> ?
> 
> Andreas

The assignment part is AFAIK optional (probably should be mentioned in
the docs). And yes, to pass special flags, use COMPILE_FLAGS.
COMPILE_DEFINITIONS should be exclusively used for preprocessor-symbols,
as is the command add_definitions().

Michael