For a detailed description of this bug see: https://sourceforge.net/tracker/?func=detail&atid=102435&aid=1053052&group_id=2435
In short the file c-incpath.c (near line 331) needs to be modified to remove the trailing slash if HAVE_DOS_BASED_FILE_SYSTEM is true. It seems on newer windows systems the trailing slash starts to become a problem. My current makefiles all have trailing slashes for each include path to support compilers that require the trailing slash. As a result I can't upgrade to the latest MinGW gcc build. I classified this as minor since it effects portability of code. -- Summary: In MinGW trailling slash forward not allowed in include path Product: gcc Version: 3.4.2 Status: UNCONFIRMED Severity: minor Priority: P2 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: ohommes at comcast dot net CC: gcc-bugs at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22133