build failing on Cygwin-- preprocessor reports cyclical #includes

[Tony Minkoff <tonym at netpro dot com>]

My builds of recent development snapshots on Cygwin fail.

I have attempted the build both on a Win2K machine and on an NT 4.0 machine
with similar results.  On each machine, Cygwin was installed from the web
within the last few days, accepting the default versions of all packages.

I have attempted to build both the 20010122 and 20010205 snapshots with the
same results.  For each snapshot, I downloaded the core and g++ components
from the snapshot, and configured with --enable-languages=c++ (and a new
directory for --prefix for each attempt).

Here is the output from one such attempt:


    [snipped output of makes in libiberty, zlib, gcc/intl, and gcc/po
directories]
    make GCC_FOR_TARGET="./xgcc -B./ -B/usr/gcc-20010205/i686-pc-cygwin/bin/
-isystem /usr/gcc-20010205/i686-pc-cygwin/include" \
      HOST_PREFIX="" HOST_PREFIX_1="loser-" \
      AR_FOR_TARGET="` if [ -f /gccobj20010205/gcc/../binutils/ar ] ; then
echo /gccobj20010205/gcc/../binutils/ar ; else if [ "i686-pc-cygwin" =
"i686-pc-cygwin" ] ; then echo ar; else t='s,^,i686-pc-cygwin-,'; echo ar |
sed -e $t ; fi; fi`" \
      AR_CREATE_FOR_TARGET="` if [ -f /gccobj20010205/gcc/../binutils/ar ] ;
then echo /gccobj20010205/gcc/../binutils/ar ; else if [ "i686-pc-cygwin" =
"i686-pc-cygwin" ] ; then echo ar; else t='s,^,i686-pc-cygwin-,'; echo ar |
sed -e $t ; fi; fi`  rc" \
      AR_FLAGS_FOR_TARGET="" \
      OLDCC="cc" CCLIBFLAGS="-O" \
      CFLAGS="-g  -W -Wall -Wwrite-strings -Wstrict-prototypes
-Wmissing-prototypes -Wtraditional -pedantic -Wno-long-long" \
      RANLIB_FOR_TARGET="` if [ -f /gccobj20010205/gcc/../binutils/ranlib ]
; then echo /gccobj20010205/gcc/../binutils/ranlib ; else if [
"i686-pc-cygwin" = "i686-pc-cygwin" ] ; then echo ranlib; else
t='s,^,i686-pc-cygwin-,'; echo ranlib | sed -e $t ; fi; fi`" \
      RANLIB_TEST_FOR_TARGET="[ -f ` if [ -f
/gccobj20010205/gcc/../binutils/ranlib ] ; then echo
/gccobj20010205/gcc/../binutils/ranlib ; else if [ "i686-pc-cygwin" =
"i686-pc-cygwin" ] ; then echo ranlib; else t='s,^,i686-pc-cygwin-,'; echo
ranlib | sed -e $t ; fi; fi` ] || ( [ "i686-pc-cygwin" = "i686-pc-cygwin" ]
&& [ -f /usr/bin/ranlib -o -f /bin/ranlib ] )" \
      NM_FOR_TARGET="` if [ -f /gccobj20010205/gcc/../binutils/nm ] ; then
echo /gccobj20010205/gcc/../binutils/nm ; else if [ "i686-pc-cygwin" =
"i686-pc-cygwin" ] ; then echo nm; else t='s,^,i686-pc-cygwin-,'; echo nm |
sed -e $t ; fi; fi`" AWK="gawk" \
      LIBGCC2_CFLAGS="-O2
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/include
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/cygwin/include
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/w32api/include  -DIN_GCC
-W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -isystem
./include   -g1  -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED " \
      INCLUDES="-I. -I. -I/cygdrive/d/gccsrc/gcc-20010205/gcc
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/.
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/config
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../include" MAYBE_USE_COLLECT2="" \
      CONFIG_H=" insn-codes.h" MACHMODE_H="machmode.h machmode.def" \
      LIB1ASMSRC='i386/cygwin.asm' \
      MAKEOVERRIDES= \
      -f libgcc.mk all
    make[3]: Entering directory `/gccobj20010205/gcc'
    for d in libgcc; do \
      if [ -d $d ]; then true; else mkdir $d; fi \
    done
    if [ -f stmp-dirs ]; then true; else touch stmp-dirs; fi
    ./xgcc -B./ -B/usr/gcc-20010205/i686-pc-cygwin/bin/ -isystem
/usr/gcc-20010205/i686-pc-cygwin/include -O2
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/include
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/cygwin/include
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/w32api/include  -DIN_GCC
-W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -isystem
./include   -g1  -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED  -I. -I.
-I/cygdrive/d/gccsrc/gcc-20010205/gcc
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/.
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/config
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../include -DL_chkstk
-xassembler-with-cpp -c
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/cygwin.asm -o
libgcc/./_chkstk.o
    ./xgcc -B./ -B/usr/gcc-20010205/i686-pc-cygwin/bin/ -isystem
/usr/gcc-20010205/i686-pc-cygwin/include -O2
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/include
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/cygwin/include
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../winsup/w32api/include  -DIN_GCC
-W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -isystem
./include   -g1  -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED  -I. -I.
-I/cygdrive/d/gccsrc/gcc-20010205/gcc
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/.
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/config
-I/cygdrive/d/gccsrc/gcc-20010205/gcc/../include  -DL_muldi3 -c
/cygdrive/d/gccsrc/gcc-20010205/gcc/libgcc2.c -o libgcc/./_muldi3.o
    In file included from
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/xm-i386.h:43,
                     from tconfig.h:6,
                     from
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/cygwin.h:36,
                     from tm.h:7,
                     from
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/xm-i386.h:43,
                     from tconfig.h:6,
                     from
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/cygwin.h:36,
                     from tm.h:7,
                     from
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/xm-i386.h:43,
                     from tconfig.h:6,
                     from
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/cygwin.h:36,
                     from tm.h:7,
    [snip]
                     from
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/cygwin.h:36,
                     from tm.h:7,
                     from
/cygdrive/d/gccsrc/gcc-20010205/gcc/config/i386/xm-i386.h:43,
                     from tconfig.h:6,
                     from /cygdrive/d/gccsrc/gcc-20010205/gcc/libgcc2.c:36:
    tm.h:4:23: #include nested too deeply
    [snip]

Cygwin.h, in fact, does not include tconfig.h, at line 36 or any other line.
To try to figure out just what the preprocessor was doing, I tried inserting
a #error directive in cygwin.h prior to line 36, but its presence was not
indicated in the build output.  I then tried inserting a #error directive in
libgcc.c (and removing it from cygwin.h), with the following result:

    [snip]
    ./xgcc -B./ -B/usr/gcc-20010122/i686-pc-cygwin/bin/ -isystem
/usr/gcc-20010122/i686-pc-cygwin/include -O2
-I/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/../winsup/include
-I/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/../winsup/cygwin/include
-I/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/../winsup/w32api/include
-DIN_GCC    -W -Wall -Wwrite-strings -Wstrict-prototypes
-Wmissing-prototypes -isystem ./include   -g1  -DIN_LIBGCC2
-D__GCC_FLOAT_NOT_NEEDED  -I. -I.
-I/cygdrive/d/cygwin/downloads/gcc-20010122/gcc
-I/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/.
-I/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/config
-I/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/../include  -DL_muldi3 -c
/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/libgcc2.c -o
libgcc/./_muldi3.o
    /cygdrive/d/cygwin/downloads/gcc-20010122/gcc/libgcc2.c:35:2: #error
libgcc2.c, line 35
    In file included from tm.h:7,
                     from
/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/config/i386/xm-i386.h:43,
                     from tconfig.h:6,
                     from
/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/libgcc2.c:37:
    /cygdrive/d/cygwin/downloads/gcc-20010122/gcc/config/i386/cygwin.h:35:2:
#error libgcc2.c, line 35
    In file included from tm.h:7,
                     from
/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/config/i386/xm-i386.h:43,
                     from tconfig.h:6,
                     from
/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/config/i386/cygwin.h:37,
                     from tm.h:7,
                     from
/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/config/i386/xm-i386.h:43,
                     from tconfig.h:6,
                     from
/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/libgcc2.c:37:
    /cygdrive/d/cygwin/downloads/gcc-20010122/gcc/config/i386/cygwin.h:35:2:
#error libgcc2.c, line 35
    In file included from tm.h:7,
                     from
/cygdrive/d/cygwin/downloads/gcc-20010122/gcc/config/i386/xm-i386.h:43,
                     from tconfig.h:6,
    [etc.  Paths in this example are different from the previous because it
was on
    a different machine.]

Any ideas what could be causing this?