Trouble with simple CMAKE tutorial - cmake

Question

I just followed the simple CMake tutorial on youtube
https://www.youtube.com/watch?v=V1YP7eJHDJE
As you can see through the youtube,
folder directory is
CMAKE-GOOD
-build
-CMakeLists.txt
-main.cpp
this is CMakeLists.txt
cmake_minimum_required(VERSION 3.14)
project(MyProject VERSION 1.0.0)
add_executable(cmake-good main.cpp)
this is main.cpp
#include <iostream>
int main()
{
std::cout << "hello, world! \n";
}
it is the only source code that I wrote.
and from this part, this will be covered my errors that I encountered
edit) I also did the cmake .. in the build directory
the result was shown in below
(base) bmssa#bmssa:~/Desktop/CMake_tutorial/CMAKE-GOOD/build$ cmake ..
-- The C compiler identification is GNU 7.5.0
-- The CXX compiler identification is GNU 7.5.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - 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: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/bmssa/Desktop/CMake_tutorial/CMAKE-GOOD/build
when I type cmake --build . in ~Desktop/CMake_tutorial_CMAKE_GOOD/build, it shows an Error with
(base) bmssa#bmssa:~/Desktop/CMake_tutorial/CMAKE-GOOD/build$ cmake --build .
[ 50%] Linking CXX executable cmake-good
/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
CMakeFiles/cmake-good.dir/build.make:96: recipe for target 'cmake-good' failed
make[2]: *** [cmake-good] Error 1
CMakeFiles/Makefile2:82: recipe for target 'CMakeFiles/cmake-good.dir/all' failed
make[1]: *** [CMakeFiles/cmake-good.dir/all] Error 2
Makefile:90: recipe for target 'all' failed
make: *** [all] Error 2
as I heard cmake --build . is similar to make,
so I tried make and it shows an error like this
(base) bmssa#bmssa:~/Desktop/CMake_tutorial/CMAKE-GOOD/build$ make
[ 50%] Linking CXX executable cmake-good
/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
CMakeFiles/cmake-good.dir/build.make:96: recipe for target 'cmake-good' failed
make[2]: *** [cmake-good] Error 1
CMakeFiles/Makefile2:82: recipe for target 'CMakeFiles/cmake-good.dir/all' failed
make[1]: *** [CMakeFiles/cmake-good.dir/all] Error 2
Makefile:90: recipe for target 'all' failed
make: *** [all] Error 2
when I type cmake --version,
cmake version 3.20.0
CMake suite maintained and supported by Kitware (kitware.com/cmake).
Can you please help me how to fix it?
I couldn't do anything because I can't even solve this one simple error in the very easy tutorial.
Please HELP ME PLEASE
Thank you
ps.
Because I don't even know what is an error in CMake, could you tell me what should I type in google to solve this?
recipe for taget?
recipe for target 'all' failed?
I don't know what should I type in google....
edit2) I also did the cmake -S . -B build/foobar and cmake --build build/foobar and this also shows the similar Error like this
(base) bmssa#bmssa:~/Desktop/CMake_tutorial/CMAKE-GOOD$ cmake -S . -B build/foobar
-- The C compiler identification is GNU 7.5.0
-- The CXX compiler identification is GNU 7.5.0
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - 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: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Configuring done
-- Generating done
-- Build files have been written to: /home/bmssa/Desktop/CMake_tutorial/CMAKE-GOOD/build/foobar
(base) bmssa#bmssa:~/Desktop/CMake_tutorial/CMAKE-GOOD$ cmake --build build/foobar
[ 50%] Building CXX object CMakeFiles/cmake-good.dir/main.cpp.o
[100%] Linking CXX executable cmake-good
/usr/lib/gcc/x86_64-linux-gnu/7/../../../x86_64-linux-gnu/Scrt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
CMakeFiles/cmake-good.dir/build.make:96: recipe for target 'cmake-good' failed
make[2]: *** [cmake-good] Error 1
CMakeFiles/Makefile2:82: recipe for target 'CMakeFiles/cmake-good.dir/all' failed
make[1]: *** [CMakeFiles/cmake-good.dir/all] Error 2
Makefile:90: recipe for target 'all' failed
make: *** [all] Error 2

Answer 1

Here is my guess to your problem. CMake is unable to find a working toolchain (Compiler, linker, etc.)
Try helping it out by specifying the environment variables CC and CXX.
https://cmake.org/cmake/help/latest/envvar/CXX.html
https://cmake.org/cmake/help/latest/envvar/CC.html
export CC = /foobar/...../gcc
export CXX = /foobar/...../g++
For future reference here is how CMake finds compilers (according to a CMake dev)
CMAKE_TOOLCHAIN_FILE (if provided)
CMAKE_LANG_COMPILER (if provided)
The environment variables CC or CXX (if provided)
Then it searches the path environment variable to see if it can find anything.
I guess in your situation none of the above worked. So setting CC and CXX fixed it.