This problem was found when building mozilla. Creating a struct which
contains a va_list element (which is actually a __builtin_va_list) causes
the C++ compiler to seg fault.

The problems is not seen when using the C compiler or compiling for sh3
(only sh4). It is preset in gcc 3.0.3, 3.2.1, 3.3.2 and 3.4 snapshot 20030222.
I suspect it was not present in gcc 2.95, but cannot confirm this.

To reproduce:
% /var/tmp/gcc-3.4-20031126/objdir/gcc/xgcc
-B/var/tmp/gcc-3.4-20031126/objdir/gcc/ -O0 nsTextFormatter.ii -m4 -c
nsTextFormatter.ii:4: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.

% cat nsTextFormatter.ii
typedef __builtin_va_list __gnuc_va_list;
typedef __gnuc_va_list va_list;

struct NumArgState{
    va_list ap;
};