I am not aware of any system with this problem, it is purely theoretical. Possibly affected targets are the c4x, i370, i960, and v850. The integrated preprocessor would benefit from greater integration with the front ends. It still feels like it has been tacked on as an after thought, which is not entirely coincidental. See character set issues , below.
Proper support has to be coordinated with the front ends.
You can get some of this with the debug switches, but not all, and not in a reloadable format. The front end must cooperate also. Integration of diagnostic reporting. The front ends could use extra information only available to the preprocessor, such as column numbers and macros under expansion. The existing code copies cpplib's internal state into the state used by diagnostic.c , which is better than writing out and processing linemarker commands, but still suboptimal.