On 10/09/2012 01:59 AM, James Bigler wrote: > On Mon, Oct 8, 2012 at 10:40 PM, James Bigler <jamesbig...@gmail.com > <mailto:jamesbig...@gmail.com>> wrote: > In my project I need to manually link against a special version of libstdc++ > add_library(a SHARED a.cpp) > set_target_properties(a PROPERTIES LINKER_LANGUAGE "C") > > add_library(b SHARED b.c) > > And here's the compiler output which has the -lstdc++ on the link line > for library a, but not for library b. [snip] > I told CMake to link the target as if it were a C target, then it decides that > it needs CXX libraries because it found CXX sources in my library. > > If I go through the trouble of specifying that I want to link the library as > if > it were C, why do the source files get to override my property?
CMake is using the C compiler to drive the link call as you request. That is all the LINKER_LANGUAGE property says: http://www.cmake.org/cmake/help/v2.8.9/cmake.html#prop_tgt:LINKER_LANGUAGE "...sets the language whose compiler is used to link the target..." However CMake knows that the sources have C++ code so it still wants to link against the C++ runtime libraries. This is the same feature that allows one to link C++ and Fortran code together. It chooses the C++ linker and adds the Fortran runtime libs. It is a feature and it is working exactly as intended. The C++ runtime libraries are detected when the CXX language is enabled. There is a CMakeCXXCompiler.cmake file under the CMakeFiles directory of the top-level build directory. It contains settings like: SET(CMAKE_CXX_IMPLICIT_LINK_LIBRARIES "stdc++;m;c") SET(CMAKE_CXX_IMPLICIT_LINK_DIRECTORIES "...") Whenever C++ sources are found in a target CMake will make sure these libraries appear on the link line or are also implicit for the linker language. You can hide the C++ runtime libraries by erasing these values: set(CMAKE_CXX_IMPLICIT_LINK_LIBRARIES "") set(CMAKE_CXX_IMPLICIT_LINK_DIRECTORIES "") That along with setting LINKER_LANGUAGE to "C" should do what you want. -Brad -- Powered by www.kitware.com Visit other Kitware open-source projects at http://www.kitware.com/opensource/opensource.html Please keep messages on-topic and check the CMake FAQ at: http://www.cmake.org/Wiki/CMake_FAQ Follow this link to subscribe/unsubscribe: http://www.cmake.org/mailman/listinfo/cmake
