C Cmake setup - undefined reference to pow() (despite -lm) - cmake

Question

I'm trying to build a project (with CLion) with the following CMakeLists.txt:
cmake_minimum_required(VERSION 3.6)
project(alfa_1)
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c11 -Wall -Wextra -lm")
set(SOURCE_FILES
src/foo.h
src/foo.c
src/bar.h
src/bar.c
src/parser.h
src/parser.c)
add_executable(alfa_1 ${SOURCE_FILES})
In foo.c I use pow() function from math.h, which I include in foo.h. And obviously foo.h is included in foo.c. In bar.c I have main that is doing nothing. Now, standard command line compilation like this
gcc -o bar bar.c bar.h foo.h foo.c -lm
works fine but building the project yields undefined reference to pow. As one can see I included -lm flag in CmakeLists.txt file, so I don't get why this linking part is not working here

Answer 1

CMAKE_CXX_FLAGS are flags for the C++ compiler. -l is a linker flag. To link to a library, use this:
target_link_libraries(alfa_1 m)
You might also want to replace -std=c11 with use of CMAKE_C_STANDARD and related variables (CMAKE_C_STANDARD_REQUIRED, CMAKE_C_EXTENSIONS), and possibly replace use of CMAKE_CXX_FLAGS with a call to target_compile_options().

Answer 2

add the link of library in the cmakeList
add_library(math STATIC path/to/file.cpp)
add_executable(cmake_hello main.cpp)
target_link_libraries(cmake_hello math)
and in the class cpp
#include "path/to/file.hpp"
for mode detaills see this link

Answer 3

In Clion this configuration solved my problem:
cmake_minimum_required(VERSION 3.13)
project(K_Nearest C)
set(CMAKE_C_STANDARD 99)
add_executable(K_Nearest main.c point.h point.c group.c group.h)
target_link_libraries(K_Nearest m)
The important step was: target_link_libraries(K_Nearest m), it should come after add_executable(...) statement.