GCC

From PortaWiki

Versions of gcc in the 2.8x era would append #include search paths provided with "-I" arguments to the include search path, rather than prepending them. So if you had "/usr/include/foo.h" and "./foo.h" and did "gcc -I. foo.c", it would pick up /usr/include/foo.h.

4.0.0 seems to generate bad code on HPPA with high optimization levels. 4.0.1 seems OK.