While building GCC 20041028 with Ada enabled, bootstrap fails while building 
libada:

../../xgcc -B../../ -c -O2 -g -O2 -W -Wall -Wwrite-strings -Wstrict-
prototypes -Wmissing-prototypes -fno-common      -gnatpg -gnata -I- -I../rts -
I. -
I/aaronwl/cs/compilers/gcc/src/cvs/head/gcc/gcc/ada /aaronwl/cs/compilers/gcc/s
rc/cvs/head/gcc/gcc/ada/make.adb -o make.o

raised STORAGE_ERROR : EXCEPTION_STACK_OVERFLOW
make[4]: *** [make.o] Error 1

From gdb:
Program received signal SIGSEGV, Segmentation fault.
gt_ggc_mx_lang_tree_node (x_p=0x3f9edc0) at ./gtype-ada.h:27
27        if (ggc_test_and_set_mark (x))
#0  gt_ggc_mx_lang_tree_node (x_p=0x3f9edc0) at ./gtype-ada.h:27
        x = (union lang_tree_node * const) 0x3f9edc0
        __FUNCTION__ = "gt_ggc_mx_lang_tree_node"
#1  0x0042b215 in gt_ggc_mx_lang_tree_node (x_p=0x41510a0) at ./gtype-ada.h:178
        x = (union lang_tree_node * const) 0x41510a0
        __FUNCTION__ = "gt_ggc_mx_lang_tree_node"
#2  0x0042b215 in gt_ggc_mx_lang_tree_node (x_p=0x3c84af0) at ./gtype-ada.h:178
        x = (union lang_tree_node * const) 0x3c84af0
        __FUNCTION__ = "gt_ggc_mx_lang_tree_node"
...

Reading specs from /aaronwl/cs/env/mingw-head-head-head-20041028/lib/gcc/i686-
pc-mingw32/4.0.0/specs
Configured with: ../../src/cvs/head/gcc/configure --enable-
languages=ada,c,c++,f95,java,objc --with-dwarf2 --enable-libmudflap --enable-
libgcj --with-win32-nlsapi=unicows --enable-libstdcxx-allocator=mt --enable-
libstdcxx-debug --enable-concept-checks --prefix=/aaronwl/cs/env/mingw-head-
head-head-20041028 --with-included-gettext --with-libiconv-
prefix=/aaronwl/cs/internat/iconv/install --with-gmp=/aaronwl/cs/env/mingw-
head-head-head-20041028 --with-mpfr=/aaronwl/cs/env/mingw-head-head-head-
20041028
Thread model: win32
gcc version 4.0.0 20041028 (experimental)

i686-pc-mingw32
Windows XP SP2 Professional
Pentium 4 1.4GHz 256MB
binutils 2.15.94 20041028
mingwrt mainline 20041028
msvcrt 7.0.2600.2180
w32api mainline 20041028
libiconv 1.9.1
gmp 4.1.4
mpfr 2.0.3
GNU Make 3.80
expect 5.26
tcl 8.4
dejagnu 1.4.2.x
Misc tools and environment from Cygwin Current Fri Oct 22 01:50:41 2004
ln with softlinks disabled
host gcc 3.4.1 (mingw special)
host binutils 2.15.91 20040904 (mingw)
host mingwrt 3.5
host w32api 3.1