I have a problem with the usage of CMake on Linux 64 bit. I have a sample in C that must link to a library (xr_arp.a) which has a link dependency on another lib (libcrypto.a). The following makefile that I did to build my sample code is linking successfully:
CFLAGS = -I../Common -I../xr -I../../../openssl/include
LIBS = ../xr/xr_arp.a ../../../openssl/lib/libcrypto.a
TARGET = sample
OBJFILES = sample.o
all: $(TARGET)
$(TARGET): Makefile $(OBJFILES)
$(CC) -o $@ $(OBJFILES) $(LIBS)
clean:
rm -rf *.o $(TARGET)
.SUFFIXES: .c .o
.c.o:
$(CC) -Wall $(CFLAGS) -c $<
However, I would like to convert this makefile to use CMake instead. When I use the following CMakeLists.txt file, I get that xr_arp.c has undefined reference to `SHA1' as it seems like it cannot link xr_arp.a to libcrypto.a:
cmake_minimum_required(VERSION 2.8)
project (SAMPLE C)
set(CMAKE_C_FLAGS "-Wall")
include_directories(
${CMAKE_CURRENT_SOURCE_DIR}
${CMAKE_CURRENT_SOURCE_DIR}/../Common
${CMAKE_CURRENT_SOURCE_DIR}/../xr
)
add_executable(
sample
sample.c
)
target_link_libraries(
sample
${CMAKE_CURRENT_SOURCE_DIR}/../../../openssl/lib/libcrypto.a
${CMAKE_CURRENT_SOURCE_DIR}/../xr/xr_arp.a
)
Can someone point me out on what is the difference between those two files? Why is it working with the makefile and it isn't with CMake? Is there any procedure I could use to force the linking between xr_arp.a and libcrypto.a? Please take note that both libs are third-party and are not mine.
Have you tried switching the order the libraries are specified in TARGET_LINK_LIBRARIES? In many cases it shouldn't make a difference, but I've run into cases with certain linkers where it does. I believe the GNU linker on Linux is one case where it makes a difference.
I think that xr_arp.a should appear first, so that the linker knows to look for SHA1 in the libraries that follow it.
Failing that, try running "make VERBOSE=1" and comparing the linker command that is generated by CMake with the one generated by the Makefile.