cmake_minimum_required(VERSION 3.9)

project(cmake-target-link-libs-strange-genexps LANGUAGES C)

file(WRITE "hello.h"
  [[
  void hello(void);
  ]])
file(WRITE "hello.c"
  [[
  #include <hello.h>
  #include <stdio.h>
  void hello(void) { puts("Hello"); }
  ]])
file(WRITE "main.c"
  [[
  #include <hello.h>
  int main(void) { hello(); return 0; }
  ]])

add_executable(main "main.c")
add_library(hello "hello.c")

target_include_directories(hello PUBLIC "${CMAKE_SOURCE_DIR}")

if (something)
  message(STATUS "not printed by default, of course")
endif ()

target_link_libraries(main PRIVATE $<$<BOOL:something>:hello>) # evaluates to "hello", wait what?