seen on current branches and the trunk, at least on x86 and x86_64:

  Matthias

$ cat x.C 
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <memory.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include <assert.h>

#define DEBUG_MODE 1

#define _DEBUG(str,param) { if( DEBUG_MODE == 1 ) { fprintf( stderr, "%s", "[DEBUG] " ); fprintf( stderr, str, param ); } }
#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif

typedef char bool_t;

typedef struct struct_secmem_conf {
 int pagesize;
 bool_t crypt;
 int crypt_key;
 bool_t to_file;
 char dumpfile[ SSIZE_MAX ];
} secmem_conf;

void init_secmem( secmem_conf* d ) {
 if( d->pagesize == 0 )
  d->pagesize = sysconf( _SC_PAGESIZE );

 _DEBUG( "Configuration: pagesize set to: %d\n", d->pagesize );
}

int main( int argc, char* argv[] ) {
 secmem_conf x;
 return 0;
}
$ gcc-4.4 -Wall x.C 
x.C: In function 'int main(int, char**)':
x.C:42: warning: unused variable 'x'
x.C:41: internal compiler error: in tree_low_cst, at tree.c:5014
Please submit a full bug report,

$ /usr/lib/gcc-snapshot/bin/gcc -Wall x.C 
x.C: In function 'int main(int, char**)':
x.C:42:14: warning: unused variable 'x'
x.C:41:5: internal compiler error: in tree_low_cst, at tree.c:6178