[CMake] How is the linker language of a library determined?

[Craig Scott]

On Wed, Nov 8, 2017 at 7:29 AM, Robin Verschueren <
robin.verschueren at gmail.com> wrote:

> Hi there,
>
> I'm building some C code into a library. The library needs to link to a
> C++ static library (IMPORTED target). I'm puzzled by the following:
>
>    - with BUILD_SHARED_LIBS=OFF (default), everything works as expected
>    and CMake sees the C library as a "C++ library" (i.e. it uses the C++
>    compiler/linker to link the two libraries together into a static library).
>    - with BUILD_SHARED_LIBS=ON however, CMake tries to link the C library
>    to the C++ library with cc (clang in my case), and I get linker errors.
>
> My questions:
>
> *What mechanism does CMake use to determine the linker language, and why
> is it different in these two cases?* Is it because I want to link a
> shared library against a static library as opposed to two static ones? Or
> is BUILD_SHARED_LIBS a red herring? Does CMake have a notion of what linker
> language to use for IMPORTED targets?
>
>
Can you confirm which CMake generator type you are using? If it is the
Xcode generator, do you get the same behaviour building at the command line
as you do from within the IDE? I only ask because your symptoms sound
eerily familiar to a problem I've seen before where linking used a
different launcher from the command line compared to the IDE (see the Xcode
section of this article
<https://crascit.com/2016/04/09/using-ccache-with-cmake/>).


-- 
Craig Scott
Melbourne, Australia
https://crascit.com
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