At the moment I find that any path that I add to the system include paths gets searched when I later #include "lib.h", so long as the header couldn't be found in the non-system search path. That's fine, that's what I expected. However, I also see that if I include a path in the non-system include paths (i.e. tcc_add_include_path), it gets searched when I say #include <lib.h>, which is not what I expected. This is demonstrated with tests in this file: https://github.com/run4flat/perl-TCC/blob/master/t/111-compile-include.t (specifically starting at line 149)
That, of course, is a Perl script. I will be happy to boil this down to a C program, but I first wanted to be sure that I hadn't lost my mind.
-- "Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." -- Brian Kernighan