[CMake] Specify the link command in CMake

[Michael Hertling]

On 09/13/2011 11:01 AM, Federico Carminati wrote:
> Hello Eric,
>    sorry for not having changed the subject, I realize it only now. Thanks for your answer. I am trying to use clang / clang++. This works if I do 
> 
> cmake $MY_SOURCE_DIRECTORY  -DCMAKE_C_COMPILER=clang  -DCMAKE_CXX_COMPILER=clang++ 
> 
> however CMake decides to use clang / clang++ as linker, and I need plain ld. However I am fine with all other flags and arguments. I would just like to have ld as linker command and not clang / clang++. I tried adding
> 
>  -DCMAKE_C_LINK_EXECUTABLE=ld \
>  -DCMAKE_CXX_LINK_EXECUTABLE=ld
> 
> with the result that the whole linker command is now just what I specify as argument to CMAKE_<LANG>_LINK_EXECUTABLE, I do not even have the executable, object files and libraries any more. Thanks for help and best regards, 
> 
> Federico Carminati
> CERN-PH 
> 1211 Geneva 23
> Switzerland
> Tel: +41 22 76 74959
> Fax: +41 22 76 68505
> Mobile: +41 76 487 4843

If you just want to replace clang/clang++ with ld in the linker command
line and if you can get along with Makefiles, you might use one of the
RULE_LAUNCH_LINK properties in order to perform a suitable last-minute
modification of the linker command line; see [1] for an example how to
tweak command lines in this way. BTW, CMAKE_<LANG>_LINK_EXECUTABLE is
a *rule* variable, i.e. it specifies the entire linker command line
including flags and object files, not just the linker executable.

Regards,

Michael

[1] http://www.mail-archive.com/cmake@cmake.org/msg38085.html

> On 13 Sep 2011, at 10:56, Eric Noulard wrote:
> 
>> 2011/9/13 Federico Carminati <Federico.Carminati at cern.ch>:
>>> Dear All,
>>>   is there a way to specify the link command in CMake? If I specify
>>>
>>> export LD=/usr/bin/ld ; cmake $MY_SOURCE_DIRECTORY
>>>
>>> it is not taken and if I set
>>
>> I dont' know if LD env var is supposed to be used at all.
>>
>>> cmake $MY_SOURCE_DIRECTORY \
>>> -DCMAKE_C_LINK_EXECUTABLE=ld \
>>> -DCMAKE_CXX_LINK_EXECUTABLE=ld
>>>
>>> what I observe is that the "entire" link command is replaced by "just" ld. Am I missing something?
>>
>> What are you trying to do?
>> Replacing the linker application while keeping the option of the one
>> CMake would have chosen?
>> Seems weird, if you change linker may be you should specify linker
>> option as well, no?
>>
>> This looks like "incomplete" cross compiling (see
>> http://www.cmake.org/Wiki/CMake_Cross_Compiling)
>> or unsupported compiler use.
>>
>> May be you can explain us what you are trying to do.
>> and please do not hijack unrelated thread for asking new question.
>>
>> -- 
>> Erk
>> Membre de l'April - « promouvoir et défendre le logiciel libre » -
>> http://www.april.org