[Bug bootstrap/52947] [4.7/4.8 Regression] bootstrap fails due to wrong include search path composition

[ktietz at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52947

Kai Tietz <ktietz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-07-05
     Ever Confirmed|0                           |1

--- Comment #6 from Kai Tietz <ktietz at gcc dot gnu.org> 2012-07-05 11:42:25 UTC ---
So, issue tracked down.  It isn't related to the change I did for 4.7 version. 
At least not in a direct way.  My changed fixed some issues, which now shown a
hidden issue about msys' make, which changes happily arguments containing a
POSIX-path to absolute DOS-style paths.
By this NATIVE_SYSTEM_HEADER_DIR (which is /mingw/include) to something like
'D:/msys/mingw/include'.  As native system-header-directory gets additionally
prefixed by the specified sysroot, this leads to merging of two absolute
DOS-style paths.

So solution for this might be to redefine NATIVE_SYSTEM_HEADER_DIR within
target's mingw32.h header for cases that TARGET_SYSTEM_ROOT is defined back to
'/mingw/include'.