CMake: Static and dynamic linking based on BUILD_TYPE
I am developing a small simulation software that depends on two libraries, the GSL and the libconfig. As a build system, I use CMake. For both the GSL and libconfig, I found cmake files and copied them into the cmake/ directory of my project.
The scenario is the following: I want the project to have several different build types, like debug, release, etc., but also a custom one called cluster, which adds -static to the GCC flags and links against the .a libraries of the GSL and the libconfig, which I assume exist.
My CMakeLists.txt looks like this so far:
# version
SET(PACKAGE_VERSION "1.0")
SET(PACKAGE_NAME "INTERFACE")
PROJECT(interface C CXX)
CMAKE_MINIMUM_REQUIRED(VERSION 2.8)
# dirs -----------------------------------------------------
SET(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake")
FIND_PACKAGE(GSL REQUIRED)
INCLUDE_DIRECTORIES(${GSL_INCLUDE_DIRS})
SET(LIBS ${LIBS} ${GSL_LIBRARIES})
FIND_PACKAGE(LibConfig REQUIRED)
INCLUDE_DIRECTORIES(${LIBCONFIG_INCLUDE_DIRS})
SET(LIBS ${LIBS} ${LIBCONFIG_LIBRARIES})
CONFIGURE_FILE("res/config.h.in" "config.h")
INCLUDE_DIRECTORIES(${CMAKE_BINARY_DIR})
SET_DIRECTORY_PROPERTIES(PROPERTIES
ADDITIONAL_MAKE_CLEAN_FILES "config.h"
)
# compilation ----------------------------------------------
ADD_EXECUTABLE( interface
interface.c interface.h config.h
helpers.c
output.c
lattice.c
genetic.c
)
# optional CFLAGS
SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -pedantic -std=c99")
SET(CMAKE_C_FLAGS_RELEASE "-O3 -ffast-math")
SET(CMAKE_C_FLAGS_CLUSTER "-O3 -ffast-math -static")
SET(CMAKE_C_FLAGS_DEBUG "-g")
SET(CMAKE_C_FLAGS_PROFILE "-g -ffast-math -pg")
TARGET_LINK_LIBRARIES(interface m ${LIBS})
# installation --------------------------------------------
INSTALL(TARGETS interface DESTINATION bin)
This adds the -static to the compiler, when I use -DCMAKE_BUILD_TYPE=cluster. The thing is, that it still links against the .so versions of the libs, which causes gcc to throw errors. At least the FindLibConfig.cmake scripts sets both a LIBCONFIG_LIBRARY and a LIBCONFIG_STATIC_LIBRARY variable, which I could use.
What is the most elegant or smart way to reach my goal?
Answer
Acording to cmake documentation, cmake uses the variable BUILD_SHARED_LIBS to determine the default for add_library().
If you set to ON cmake will assume all add_library() call will be as
add_library(target SHARED lib1 lib2 ...)
For example something like -DBUILD_SHARED_LIBS=ON on the cmake command line may do what you are asking.