Bootstrap broken by ppl/cloog config problem: finds non-system/non-standard "/include" dir

[Dave Korn <dave dot korn dot cygwin at googlemail dot com>]

  A quick head's-up, in case anyone else runs into this or is working on it:

  Yesterday I installed the new ppl and cloog packages from my distro
(Cygwin), and today GCC doesn't bootstrap.  This is triggered by an unusual
environment on my build machine, but I think it definitely exposes something
wrong in the configury changes related.

  The 'unusual environment' on my machine is that I have a "/include" dir,
full of header files with the standard names, some of which are bogus enough
to trigger compiler warnings:

/gnu/gcc/obj7ppl/./prev-gcc/xgcc -B/gnu/gcc/obj7ppl/./prev-gcc/
-B/opt/gcc-tools/i686-pc-cygwin/bin/ -c  -g -O2 -DIN_GCC   -W -Wall
-Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wcast-qual
-Wold-style-definition -Wc++-compat -Wmissing-format-attribute -pedantic
-Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -Werror
-fno-common  -DHAVE_CONFIG_H -DGENERATOR_FILE -I. -Ibuild -I/gnu/gcc/gcc/gcc
-I/gnu/gcc/gcc/gcc/build -I/gnu/gcc/gcc/gcc/../include
-I/gnu/gcc/gcc/gcc/../libcpp/include -I/usr/include -I/usr/include
-I/gnu/gcc/gcc/gcc/../libdecnumber -I/gnu/gcc/gcc/gcc/../libdecnumber/dpd
-I../libdecnumber -I/include  -I/include -DCLOOG_PPL_BACKEND   -o
build/genmodes.o /gnu/gcc/gcc/gcc/genmodes.c
cc1: warnings being treated as errors
In file included from /gnu/gcc/gcc/gcc/system.h:41,
                 from /gnu/gcc/gcc/gcc/genmodes.c:22:
/include/stdio.h:615: error: no previous prototype for '__sgetc_r'
make[3]: *** [build/genmodes.o] Error 1
make[3]: Leaving directory `/gnu/gcc/obj7ppl/gcc'
make[2]: *** [all-stage2-gcc] Error 2


  However, I think the details aren't relevant.  "/include" is not a standard
location on my target, and should not have been searched.  It is outside
$prefix, and one level above /usr, where --with-gmp and --with-mpfr point; I
cannot see any reason why it should even be considered speculatively.

$ /gnu/gcc/gcc/configure  '--prefix=/opt/gcc-tools'  '-v' '--with-gmp=/usr'
'--with-mpfr=/usr' '--enable-bootstrap'
'--enable-version-specific-runtime-libs' '--with-slibdir=/usr/bin'
'--libexecdir=/usr/lib' '--enable-static' '--enable-shared'
'--enable-shared-libgcc' '--disable-__cxa_atexit' '--with-gnu-ld' '--with
-gnu-as' '--with-dwarf2' '--disable-sjlj-exceptions' '--disable-symvers'
'--enable-libjava' '--enable-interpreter' '--program-suffix=-4'
'--enable-libgomp' '--enable-libssp' '--disable-libada'
'--enable-threads=posix' '--with-arch=i686' '--with-tune=generic' 'CC=gcc-4'
'CXX=g++-4' 'CC_FOR_TARGET=gcc-4' 'CXX_FOR_TARGET=g++-4'
'--with-ecj-jar=/usr/share/java/ecj.jar' 'LD=/opt/gcc-tools/bin/ld.exe'
'LD_FOR_TARGET=/opt/gcc-tools/bin/ld.exe' 'AS=/opt/gcc-tools/bin/as.exe'
'AS_FOR_TARGET=/opt/gcc-tools/bin/as.exe' '--disable-win32-registry'
'--enable-libgcj-debug' '--enable-languages=c,c++,java,fortran' 2>&1 | tee
conf.log


  As I said, this didn't happen the day before when I configured similarly but
without cloog and ppl libs present in /usr/lib, so I reckon it must be
triggered by related configury.  I'll do some more digging and find out why it
happens; so far I've just verified that "-I/include" was not present on
command-lines in the previous bootstrap and only appeared in the new failing
build.

  I'm about to start looking through the config logs; if anyone knows anything
or has any ideas about this, please share!


    cheers,
      DaveK