There is no /lib/cpp. There doesn't seem to be any need to run any C++ in stage 1 anyway.
checking whether -lc should be explicitly linked in... yes checking dynamic linker characteristics... Win32 ld.exe checking how to hardcode library paths into programs... immediate checking whether stripping libraries is possible... yes checking if libtool supports shared libraries... yes checking whether to build shared libraries... yes checking whether to build static libraries... yes checking how to run the C++ preprocessor... /lib/cpp configure: error: in `/cygdrive/c/jimdata/home/cvsroot/gcc-obj/gcc': configure: error: C++ preprocessor "/lib/cpp" fails sanity check See `config.log' for more details. make[1]: *** [configure-gcc] Error 1 make[1]: Leaving directory `/cygdrive/c/jimdata/home/cvsroot/gcc-obj' make: *** [all] Error 2 uname -a CYGWIN_NT-5.1 mckelvey-xp 1.7.1(0.218/5/3) 2009-12-07 11:48 i686 Cygwin BUILDING: alias CONFIGURECVS='/cygdrive/c/jimdata/home/cvsroot/gcc/configure --verbose --enable-threads --disable-nls --enable-checking=release --disable-win32-registry --disable-sjlj-exceptions --disable-bootstrap --enable-languages=c,c++ 2>&1 | tee clog' alias BUILD='nice make CFLAGS='\'''\'' BOOT_CFLAGS='\'''\'' LIBCFLAGS='\''-g -O'\'' CXXFLAGS='\''-O'\'' LIBCXXFLAGS='\''-g -O'\'' 2>&1 | tee log' I'll attach the full log and the log from configure. -- Summary: Bootstrap failure: "/lib/cpp" fails sanity check Product: gcc Version: 4.5.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: bootstrap AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: mckelvey at maskull dot com GCC build triplet: i686-pc-cygwin GCC host triplet: i686-pc-cygwin GCC target triplet: i686-pc-cygwin http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43619