Issues with linking GLFW to the executable with CMake - cmake

Question

I am currently trying to link the GLFW library with my executable files in CLion. After hours of research and trial & error, I am stuck. I am using find_package() to locate my GLFW library. For some reason my FindGLFW.cmake file seems to correctly locate the library in /usr/local/lib/libglfw.a when using find_library(), but my CMakeLists.txt returns empty with find_package(). I don't really understand how that's possible. Could someone help me out?
CMakeLists.txt:
cmake_minimum_required(VERSION 3.15)
project(learnopengl)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/CMake)
find_package(glfw 3.3 REQUIRED)
message(STATUS "(CMakeLists.txt) GLFW: [${glfw}]")
if (NOT glfw)
message(SEND_ERROR "(CMakeLists) Did not find glfw_library")
endif()
add_executable(learnopengl src/main.cpp)
target_link_libraries(learnopengl glfw)
FindGLFW.cmake
find_library( GLFW_LIBRARY
NAMES
glfw3 glfw
PATHS
${GLFW_LOCATION}/lib
$ENV{GLFW_LOCATION}/lib
/usr/lib64
/usr/lib
/usr/local/lib64
/usr/local/lib
NO_DEFAULT_PATH
DOC "The GLFW library"
)
message(STATUS "(FindGLFW.cmake) GLFW_INCLUDE_DIR: [${GLFW_INCLUDE_DIR}]")
message(STATUS "(FindGLFW.cmake) GLFW_LIB: [${GLFW_LIBRARY}]")
if (NOT GLFW_LIBRARY)
message(SEND_ERROR "(FindGLFW.cmake) Did not find glfw_library")
Output when running cmake ..
-- (FindGLFW.cmake) GLFW_INCLUDE_DIR: [/usr/local/include]
-- (FindGLFW.cmake) GLFW_LIB: [/usr/local/lib/libglfw3.a]
-- (CMakeLists.txt) GLFW: []
CMake Error at CMakeLists.txt:12 (message):
(CMakeLists) Did not find glfw_library
When I tried to directly include find_library() in my CMakeLists.txt instead, it did locate the library, but when I tried to link it with my executable, I got a linker error saying it couldn't locate the library:
CMakeLists.txt
cmake_minimum_required(VERSION 3.15)
project(learnopengl)
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/CMake)
find_library( GLFW_LIBRARY
NAMES
glfw3 glfw
PATHS
${GLFW_LOCATION}/lib
$ENV{GLFW_LOCATION}/lib
/usr/lib64
/usr/lib
/usr/local/lib64
/usr/local/lib
NO_DEFAULT_PATH
DOC "The GLFW library"
)
message(STATUS "(FindGLFW.cmake) GLFW_LIB: [${GLFW_LIBRARY}]")
if (NOT GLFW_LIBRARY)
message(SEND_ERROR "(CMakeLists.txt) Did not find glfw_library")
endif()
add_executable(learnopengl src/main.cpp)
target_link_libraries(learnopengl GLFW_LIBRARY)
Output:
~/dev/projects/opengl/learnopengl/build  cmake ..
-- (CMakeLists.txt) GLFW_LIB: [/usr/local/lib/libglfw3.a]
-- Configuring done
-- Generating done
-- Build files have been written to: /Users/Philipp/dev/projects/opengl/learnopengl/build
~/dev/projects/opengl/learnopengl/build  cmake --build .
[ 50%] Linking CXX executable learnopengl
ld: library not found for -lGLFW_LIBRARY
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [learnopengl] Error 1
make[1]: *** [CMakeFiles/learnopengl.dir/all] Error 2
make: *** [all] Error 2
I would really appreciate some hints as to what I am doing wrong. I can't see why it wouldn't locate/link the library correctly.
Thank you!

Answer 1

In cmake, arguments are case sensitive, so find_package should be
find_package(GLFW 3.3 REQUIRED)
Linker problem can be found easily in the logs. You are trying to link -lGLFW_LIBRARY, however what you want to link is GLFW_LIBRARY's value, /usr/local/lib/libglfw3.a .
target_link_libraries(learnopengl ${GLFW_LIBRARY})