How to fix: CMake-defined macro won't be received by compiler - c++

Question

SOLVED! = instead of - in the CMakeLists.txt in say-hello directory
I have problems with defining a preprocessor variable with CMake according to vector-of-bool's CMake-Tutorial https://www.youtube.com/watch?v=SYgESCQeGJY&list=PLK6MXr8gasrGmIiSuVQXpfFuE1uPT615s&index=8.
Obviously, I am using a different CMake-Version than the one that he's using in the video. But before changing my version I want to tackle the problem here.
After configuring successfully via cmake .., I run make and receive the following:
[ 25%] Building CXX object say-hello/CMakeFiles/say-hello.dir/src/say-hello/hello.cpp.o
<command-line>:0:14: warning: ISO C++11 requires whitespace after the macro name
/home/maximilian/Dokumente/02_Programmieren/VSCMAKE/say-hello/src/say-hello/hello.cpp: In function ‘void hello::say()’:
<command-line>:0:17: error: expected ‘;’ before numeric constant
/home/maximilian/Dokumente/02_Programmieren/VSCMAKE/say-hello/src/say-hello/hello.cpp:7:43: note: in expansion of macro ‘HELLO_VERSION’
std::cout << "Hello (Version " << HELLO_VERSION << ")\n";
^~~~~~~~~~~~~
say-hello/CMakeFiles/say-hello.dir/build.make:62: recipe for target 'say-hello/CMakeFiles/say-hello.dir/src/say-hello/hello.cpp.o' failed
make[2]: *** [say-hello/CMakeFiles/say-hello.dir/src/say-hello/hello.cpp.o] Error 1
CMakeFiles/Makefile2:90: recipe for target 'say-hello/CMakeFiles/say-hello.dir/all' failed
make[1]: *** [say-hello/CMakeFiles/say-hello.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2
I am using:
Linux
g++ 8.1
C++11
CMake 3.14.4
Visual Studio Code
Top CMakeLists.txt
cmake_minimum_required(VERSION 3.14.4)
project(MyProject VERSION 1.0.0)
set(CMAKE_CXX_STANDARD 11)
add_subdirectory(say-hello)
add_subdirectory(mainsrc)
CMakeLists.txt in mainsrc
add_executable(main.out main.cpp)
target_link_libraries(main.out PRIVATE say-hello)
main.cpp
#include <iostream>
#include <say-hello/hello.hpp>
int main(){
hello::say();
return 0;
}
CMakeLists.txt in say-hello
add_library(say-hello
src/say-hello/hello.cpp
src/say-hello/hello.hpp
)
target_include_directories(say-hello PUBLIC "${CMAKE_CURRENT_SOURCE_DIR}/src")
target_compile_definitions(say-hello PUBLIC HELLO_VERSION-4)
hello.hpp
#ifndef HELLO
#define HELLO
//#define SAYHELLOVERSION 4
namespace hello{
void say();
}
#endif
hello.cpp
#include <iostream>
#include "hello.hpp"
namespace hello{
void say(){
//int version = SAYHELLOVERSION;
std::cout << "Hello (Version " << HELLO_VERSION << ")\n";
}
}