Prolog_BFS | simple implementation of a breadth first search prolog | Interpreter library

By default, CMake de-duplicates compile and link options. This is explicitly stated in the documentation for target_compile_options command. Also, the documentation suggests to use SHELL: prefix for avoid breaking groups because of that:

The final set of compile or link options used for a target is constructed by accumulating options from the current target and the usage requirements of its dependencies. The set of options is de-duplicated to avoid repetition. While beneficial for individual options, the de-duplication step can break up option groups. For example, -D A -D B becomes -D A B. One may specify a group of options using shell-like quoting along with a SHELL: prefix. The SHELL: prefix is dropped, and the rest of the option string is parsed using the separate_arguments() UNIX_COMMAND mode. For example, "SHELL:-D A" "SHELL:-D B" becomes -D A -D B.

That is, in your case you may specify