About LDLIBS etc.

Usage
1

Hi community,

I wonder why CMake does not support these four settings directly:
CPPFLAGS, CFLAGS, LDFLAGS, LDLIBS.

I list their correspondings in CMake. I’m not sure if they are correct.

CPPFLAGS: include_directories(./foo), add_compile_definitions(VAR)
CFLAGS  : add_compile_options(-std=c11)
LDFLAGS : add_link_options(-L./foo)
LDLIBS  : link_libraries(foo)

The other day, I tried to use both -L and -l with

add_link_options(-L./foo -lfoo)

It fails to compile becuase -l belongs to LDLIBS and should occurs
after .o object files.

I think Autotools does not have LDLIBS but I still can put both -L and -l with

LDFLAGS=-L./foo -lfoo

Autotools uses libtool to arrange -l after .o object files, and it compiles.

2

You should use [target_]link_directories for -L flags and [target_]link_libraries for -l flags. Better is to construct the absolute path and just use that directly.

3

Hi Ben,

All the compiling and linking options can be set by
these six CMake commands, right?

link_directories        # LDFLAGS  += -L../foo
link_libraries          # LDLIBS   += -lfoo
include_directories     # CPPFLAGS += -I../foo
add_compile_definitions # CPPFLAGS += -DNDEBUG

add_link_options(-fsanitize=address) # LDFLAGS += ..
add_compile_options(-std=c11)        # CFLAGS  += ..

Can I have some suggestions on my little CMakeLists.txt as follow?

Thanks

$ vi CMakeLists.txt

cmake_minimum_required(VERSION 3.18)
project(MyProject VERSION 1.0)
set(CMAKE_BUILD_RPATH_USE_ORIGIN TRUE)
set(CMAKE_INSTALL_RPATH $ORIGIN/../lib)

if (CMAKE_BUILD_TYPE STREQUAL Debug)
  add_link_options(-fsanitize=address)
endif()
#link_libraries(foo)
#link_directories(../foo)
#include_directories(../foo)
#add_compile_definitions(VAR) # VAR=value
add_compile_options(-std=c11) # .cpp
#set(CMAKE_C_COMPILER gcc) # .cpp
file(GLOB SOURCES *.c) # .cpp

add_executable(main ${SOURCES})
#add_library(foo SHARED ${SOURCES})
#set_target_properties(foo PROPERTIES VERSION 1.2.3 SOVERSION 1)
#add_subdirectory(./foo)

# make -C build DESTDIR=~/foo install
install(TARGETS main) # foo)
#file(GLOB LIBRARIES ../lib/*.so*)
#install(FILES ${LIBRARIES} DESTINATION lib)

# cmake -S . -B build -DCMAKE_BUILD_TYPE=Debug # Release
# cmake --build build -v # verbose

$