Can NOT find out dynamic header file generated by configure_file.

Code
1

I have a dynamic header Version.hpp generated by configure_file command of cmake-3.25.

I can normally use it at the top of the source tree as is, but can NOT use it in a subdirectory of the tree.

Like this:
The top level CMakeLists.txt:

cmake_minimum_required( VERSION 3.16.0 )
set( PROJECT_VERSION_MAJOR 1 )
set( PROJECT_VERSION_MINOR 2 )
set( PROJECT_VERSION_PATCH 3 )
set( PROJECT_VERSION ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH} )
set( PROJECT_DESCRIPTION "try-cmake" )
project( try-cmake VERSION ${PROJECT_VERSION} DESCRIPTION ${PROJECT_DESCRIPTION} LANGUAGES CXX )
configure_file( Version.hpp.in Version.hpp )
# include_directories( "." )
set( CMAKE_INCLUDE_CURRENT_DIR ON )
add_executable( try-cfg Main.cpp )
install( TARGETS try-cfg RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR} )
add_subdirectory( unit-test )

And the CMakeList.txt in subdirectory unit-test:

cmake_minimum_required( VERSION 3.16.0 )

# This line does not work
include_directories( ".." )
# and this neither
set( CMAKE_INCLUDE_CURRENT_DIR ON )

add_executable( ut ut-main.cpp )
install( TARGETS ut RUNTIME DESTINATION test )

And the source Main.cpp in the top( can be compiled):

#include <iostream>
#include <iomanip>
#include "Version.hpp"
using namespace std;
int main() {
	cout << "Product Version:" << PROJECT_VERSION << endl;
};

And the source ut-main.cpp at a subdir(can NOT be compiled):

#include <iostream>
#include <iomanip>
#include "Version.hpp"
using namespace std;
int main() {
	cout << "Unit Test Version:" << PROJECT_VERSION << endl;
};

The error text:

fatal error: Version.hpp: No such file or directory
3 | #include “Version.hpp”
| ^~~~~~~~~~~~~
compilation terminated.

Thanks!

2

Does that work?

add_executable(ut ut-main.cpp)

target_include_directories(ut
    PRIVATE
        ${CMAKE_CURRENT_SOURCE_DIR}/..
        # or
        #${CMAKE_SOURCE_DIR} # probably not a good idea, if your top-level project might be used as a sub-project elsewhere
)
3

See too the CMake Tutorial