Error out if no included libraries were found

Author: Flamefire

include/BoostRoot.cmake

@@ -244,16 +244,23 @@ endmacro()
 file(GLOB __boost_libraries RELATIVE "${BOOST_SUPERPROJECT_SOURCE_DIR}/libs" "${BOOST_SUPERPROJECT_SOURCE_DIR}/libs/*/CMakeLists.txt" "${BOOST_SUPERPROJECT_SOURCE_DIR}/libs/numeric/*/CMakeLists.txt")
 
 # Check for mistakes in BOOST_INCLUDE_LIBRARIES
+if(BOOST_INCLUDE_LIBRARIES)
+  set(__boost_any_library_found OFF)
+  foreach(__boost_included_lib IN LISTS BOOST_INCLUDE_LIBRARIES)
 
-foreach(__boost_included_lib IN LISTS BOOST_INCLUDE_LIBRARIES)
+    if(NOT "${__boost_included_lib}/CMakeLists.txt" IN_LIST __boost_libraries)
 
-  if(NOT "${__boost_included_lib}/CMakeLists.txt" IN_LIST __boost_libraries)
+      message(WARNING "Library '${__boost_included_lib}' given in BOOST_INCLUDE_LIBRARIES has not been found.")
 
-    message(WARNING "Library '${__boost_included_lib}' given in BOOST_INCLUDE_LIBRARIES has not been found.")
+    else()
+      set(__boost_any_library_found ON)
+    endif()
 
+  endforeach()
+  if(NOT __boost_any_library_found)
+    message(FATAL_ERROR "None of the libraries given in BOOST_INCLUDE_LIBRARIES has been found so no libraries would be build. Verify BOOST_INCLUDE_LIBRARIES (${BOOST_INCLUDE_LIBRARIES})")
   endif()
-
-endforeach()
+endif()
 
 # Scan for dependencies