The CMAKE_*_COMPILER variables are set correctly.
The CMAKE_*_IMPLICIT_LINK_LIBRARIES have a whole bunch of libraries probably
generated from the Cray wrapper.
It is interesting to note that the stdc++ library is in
CMAKE_C_IMPLICIT_LINK_LIBRARIES and CMAKE_Fortran_IMPLICIT_LINK_LIBRARIES but
not in CMAKE_CXX_IMPLICIT_LINK_LIBRARIES.
Also, when the LINKER_LANGUAGE variable is not set, CMake links with the C
compiler but does not add the stdc++ library.
On the Cray systems, the wrappers correctly invoke all necessary libraries,
thus CMake is working harder than it needs to. Is there any way to tell CMake
not to add these other IMPLICIT_LINK_LIBRARIES when doing a mixed language
build?
Thanks,
Lucas Pettey, PhD
HPCMP PETTT EQM CTA Lead
ERDC-DSRC OnSite
Vicksburg, MS
512-297-9833 Mobile (preferred)
601-634-2980 Office
lucas.pet...@engilitycorp.com
________________________________________
From: Brad King [brad.k...@kitware.com]
Sent: Wednesday, May 27, 2015 12:36 PM
To: Pettey, Lucas @ EngilityCorp
Cc: cmake@cmake.org; Dan Liew
Subject: Re: [CMake] Linking C program to external C++ library
On 05/21/2015 06:00 PM, lucas.pet...@engilitycorp.com wrote:
> I am trying to compile a code written in C, but using an external
> library that contains C++ functions. I am on a Cray system and
> everything works if I manually link with the cray CC wrapper.
> When I change the linker language with this command:
>
> set_property(TARGET adh PROPERTY LINKER_LANGUAGE CXX)
>
> CMake is using the CC wrapper, but adding -lstdc++ to the link line.
> This causes an error. Can anyone tell me how to not get this added library?
CMake detects the libraries implicitly added by the compiler front-end
for each language. When mixing languages it chooses to link using the
compiler front-end for one of the languages and adds the implicit
libraries needed for other languages and not added by the chosen one.
This case looks strange because you are telling it to link with the
C++ compiler but CMake is still adding the implicit library for C++.
Look at CMakeFiles/${CMAKE_VERSION}/CMake*Compiler.cmake for details
of the compiler detected for each language. Look for these variables:
CMAKE_C_COMPILER
CMAKE_C_IMPLICIT_LINK_LIBRARIES
CMAKE_CXX_COMPILER
CMAKE_CXX_IMPLICIT_LINK_LIBRARIES
To what are they set?
Thanks,
-Brad
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