Define compiler and linker in CMAKE - cmake

Question

I would like to use CMAKE to compile a special piece of code in C99 with language extensions. Therefore I have to use a "custom" compiler and linker /your/path/to/compiler and /your/path/to/linker. How can I define the compiler and the linker command used by CMAKE?
EDIT:
I tried to define the compiler and linker as suggested by Equod:
set(CMAKE_C_COMPILER /your/path/to/compiler)
set(CMAKE_CUSTOM_LINKER /your/path/to/linker)
set(CMAKE_C_LINK_EXECUTABLE
"<CMAKE_CUSTOM_LINKER> <FLAGS> <CMAKE_CXX_LINK_FLAGS> <LINK_FLAGS> <OBJECTS> -o <TARGET> <LINK_LIBRARIES>")
But CMAKE is still not taking it:
-- Building for: Visual Studio 15 2017
-- Selecting Windows SDK version 10.0.14393.0 to target Windows 10.0.18363.
-- The C compiler identification is MSVC 19.16.27040.0
-- The CXX compiler identification is MSVC 19.16.27040.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: C:/Programms/VisualStudio/2017/Professional/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: C:/Programms/VisualStudio/2017/Professional/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: C:/your/path/to/source/build
What I forgot to mention before, I am working on a Windows machine and the executable of th compiler and linker is in the PATH.
EDIT:
Here is my CMakeLists.txt
cmake_minimum_required(VERSION 3.10)
project(MyProject
VERSION 1.0
DESCRIPTION "This is MyProject"
LANGUAGES C
)
set(CMAKE_C_COMPILER my_compiler)
set(CMAKE_C_LINK_EXECUTABLE my_linker)
configure_file(include/myproject_config.h.in include/myproject_config.h)
set(HEADER_FILES include/main.h include/somefunc.h)
set(SOURCE_FILES src/main.c src/somefunc.c)
add_executable(MyProject ${HEADER_FILES} ${SOURCE_FILES})
target_include_directories(MyProject PUBLIC "${PROJECT_BINARY_DIR}" )
target_include_directories(MyProject PUBLIC "../include" )
P.S.: my_compiler and my_linker are in PATH of cmd and PowerShell.
EDIT:
I installed MinGW now. I have make in my PATH as well. I updated the CMakeLists.txt file above. The make command tries to compile the code now with:
my_compiler #CMakeFiles/MyProject.dir/includes_C.rsp -o CMakeFiles\MyProject.dir\src\main.c.obj -c "C:\mypath\main.c"
But this is not working because I need a command like:
my_compiler -I="../include" "C:\mypath\main.c"
What CMake commands do I need to configure such a behavior?

Answer 1

CMake as default C compiler uses CC environment variables. You can also specify a different compiler and linker setting CMake variables:
Compiler:
set(CMAKE_C_COMPILER /your/path/to/compiler)
Linker:
set(CMAKE_CUSTOM_LINKER /your/path/to/linker)
set(CMAKE_C_LINK_EXECUTABLE
"<CMAKE_CUSTOM_LINKER> <FLAGS> <CMAKE_CXX_LINK_FLAGS> <LINK_FLAGS> <OBJECTS> -o <TARGET> <LINK_LIBRARIES>")
To better understand why linker settings are done in two steps I'd suggest taking a look at how those variables are managed internally by CMake:
CMake on github