[Bug c++/42124] New: warning: array subscript is below array bounds

["djszapi at archlinux dot us" <gcc-bugzilla at gcc dot gnu dot org>]

CPP code:

#include <malloc.h>
#include <errno.h>

const int INT_INVALID = 0x80000000;

template <class T, int N> class TOPLIST
{
        int ind[N], n, lim;
        T vals[N];

public:
        TOPLIST() { n = 0; lim = N; }
        void reset() { n = 0; }

        void add(int index, T value)
        {
        int m;
        if(n==lim) { if(vals[n-1]>=value) return; } else n++;
        for(m=n-1; m>0 && vals[m-1]<value; m--) {
                vals[m] = vals[m-1];
                ind[m] = ind[m-1];
        }
                vals[m] = value;
        ind[m] = index;
        }

        T val(int index) {
        if(index<0 || index>=n) return T(0);
        else return vals[index];
        }

        int indx(int index) {
        if(index<0 || index>=n) return INT_INVALID;
        else return ind[index];
        }

        bool IsValid(void) const { return n>0; }
};

const char C39PAT[4][11] = {
        "0111221211", "1211211112", "2112211112", "3212211111"
};

int ReadC39()
{
        TOPLIST<int, 3> T;
        int c;
        for(c=0; c<4; c++) T.add(c, c);

        for(c=0; c<4; c++)
                if(C39PAT[c][T.indx(0)+1]=='2')
                        break;

        return (c<4) ? C39PAT[c][0] : '?';
}

int main()
{
        return 0;
}




Command which produces the above mentioned warning:

g++ -v --save-temp xxx.cpp -O3 -Wall






And the *.ii files.

# 1 "xxx.cpp"
# 1 "<built-in>"
# 1 "<command-line>"
# 1 "xxx.cpp"

# 1 "/usr/include/malloc.h" 1 3 4
# 24 "/usr/include/malloc.h" 3 4
# 1 "/usr/include/features.h" 1 3 4
# 347 "/usr/include/features.h" 3 4
# 1 "/usr/include/sys/cdefs.h" 1 3 4
# 353 "/usr/include/sys/cdefs.h" 3 4
# 1 "/usr/include/bits/wordsize.h" 1 3 4
# 354 "/usr/include/sys/cdefs.h" 2 3 4
# 348 "/usr/include/features.h" 2 3 4
# 371 "/usr/include/features.h" 3 4
# 1 "/usr/include/gnu/stubs.h" 1 3 4



# 1 "/usr/include/bits/wordsize.h" 1 3 4
# 5 "/usr/include/gnu/stubs.h" 2 3 4


# 1 "/usr/include/gnu/stubs-32.h" 1 3 4
# 8 "/usr/include/gnu/stubs.h" 2 3 4
# 372 "/usr/include/features.h" 2 3 4
# 25 "/usr/include/malloc.h" 2 3 4
# 1 "/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include/stddef.h" 1 3 4
# 149 "/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include/stddef.h" 3 4
typedef int ptrdiff_t;
# 211 "/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include/stddef.h" 3 4
typedef unsigned int size_t;
# 26 "/usr/include/malloc.h" 2 3 4
# 1 "/usr/include/stdio.h" 1 3 4
# 30 "/usr/include/stdio.h" 3 4
extern "C" {



# 1 "/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include/stddef.h" 1 3 4
# 35 "/usr/include/stdio.h" 2 3 4

# 1 "/usr/include/bits/types.h" 1 3 4
# 28 "/usr/include/bits/types.h" 3 4
# 1 "/usr/include/bits/wordsize.h" 1 3 4
# 29 "/usr/include/bits/types.h" 2 3 4


typedef unsigned char __u_char;
typedef unsigned short int __u_short;
typedef unsigned int __u_int;
typedef unsigned long int __u_long;


typedef signed char __int8_t;
typedef unsigned char __uint8_t;
typedef signed short int __int16_t;
typedef unsigned short int __uint16_t;
typedef signed int __int32_t;
typedef unsigned int __uint32_t;




__extension__ typedef signed long long int __int64_t;
__extension__ typedef unsigned long long int __uint64_t;







__extension__ typedef long long int __quad_t;
__extension__ typedef unsigned long long int __u_quad_t;
# 131 "/usr/include/bits/types.h" 3 4
# 1 "/usr/include/bits/typesizes.h" 1 3 4
# 132 "/usr/include/bits/types.h" 2 3 4


__extension__ typedef __u_quad_t __dev_t;
__extension__ typedef unsigned int __uid_t;
__extension__ typedef unsigned int __gid_t;
__extension__ typedef unsigned long int __ino_t;
__extension__ typedef __u_quad_t __ino64_t;
__extension__ typedef unsigned int __mode_t;
__extension__ typedef unsigned int __nlink_t;
__extension__ typedef long int __off_t;
__extension__ typedef __quad_t __off64_t;
__extension__ typedef int __pid_t;
__extension__ typedef struct { int __val[2]; } __fsid_t;
__extension__ typedef long int __clock_t;
__extension__ typedef unsigned long int __rlim_t;
__extension__ typedef __u_quad_t __rlim64_t;
__extension__ typedef unsigned int __id_t;
__extension__ typedef long int __time_t;
__extension__ typedef unsigned int __useconds_t;
__extension__ typedef long int __suseconds_t;

__extension__ typedef int __daddr_t;
__extension__ typedef long int __swblk_t;
__extension__ typedef int __key_t;


__extension__ typedef int __clockid_t;


__extension__ typedef void * __timer_t;


__extension__ typedef long int __blksize_t;




__extension__ typedef long int __blkcnt_t;
__extension__ typedef __quad_t __blkcnt64_t;


__extension__ typedef unsigned long int __fsblkcnt_t;
__extension__ typedef __u_quad_t __fsblkcnt64_t;


__extension__ typedef unsigned long int __fsfilcnt_t;
__extension__ typedef __u_quad_t __fsfilcnt64_t;

__extension__ typedef int __ssize_t;



typedef __off64_t __loff_t;
typedef __quad_t *__qaddr_t;
typedef char *__caddr_t;


__extension__ typedef int __intptr_t;


__extension__ typedef unsigned int __socklen_t;
# 37 "/usr/include/stdio.h" 2 3 4
# 45 "/usr/include/stdio.h" 3 4
struct _IO_FILE;



typedef struct _IO_FILE FILE;





# 65 "/usr/include/stdio.h" 3 4
typedef struct _IO_FILE __FILE;
# 75 "/usr/include/stdio.h" 3 4
# 1 "/usr/include/libio.h" 1 3 4
# 32 "/usr/include/libio.h" 3 4
# 1 "/usr/include/_G_config.h" 1 3 4
# 15 "/usr/include/_G_config.h" 3 4
# 1 "/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include/stddef.h" 1 3 4
# 16 "/usr/include/_G_config.h" 2 3 4




# 1 "/usr/include/wchar.h" 1 3 4
# 83 "/usr/include/wchar.h" 3 4
typedef struct
{
  int __count;
  union
  {

    unsigned int __wch;



    char __wchb[4];
  } __value;
} __mbstate_t;
# 21 "/usr/include/_G_config.h" 2 3 4

typedef struct
{
  __off_t __pos;
  __mbstate_t __state;
} _G_fpos_t;
typedef struct
{
  __off64_t __pos;
  __mbstate_t __state;
} _G_fpos64_t;
# 53 "/usr/include/_G_config.h" 3 4
typedef int _G_int16_t __attribute__ ((__mode__ (__HI__)));
typedef int _G_int32_t __attribute__ ((__mode__ (__SI__)));
typedef unsigned int _G_uint16_t __attribute__ ((__mode__ (__HI__)));
typedef unsigned int _G_uint32_t __attribute__ ((__mode__ (__SI__)));
# 33 "/usr/include/libio.h" 2 3 4
# 53 "/usr/include/libio.h" 3 4
# 1 "/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include/stdarg.h" 1 3 4
# 40 "/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include/stdarg.h" 3 4
typedef __builtin_va_list __gnuc_va_list;
# 54 "/usr/include/libio.h" 2 3 4
# 170 "/usr/include/libio.h" 3 4
struct _IO_jump_t; struct _IO_FILE;
# 180 "/usr/include/libio.h" 3 4
typedef void _IO_lock_t;





struct _IO_marker {
  struct _IO_marker *_next;
  struct _IO_FILE *_sbuf;



  int _pos;
# 203 "/usr/include/libio.h" 3 4
};


enum __codecvt_result
{
  __codecvt_ok,
  __codecvt_partial,
  __codecvt_error,
  __codecvt_noconv
};
# 271 "/usr/include/libio.h" 3 4
struct _IO_FILE {
  int _flags;




  char* _IO_read_ptr;
  char* _IO_read_end;
  char* _IO_read_base;
  char* _IO_write_base;
  char* _IO_write_ptr;
  char* _IO_write_end;
  char* _IO_buf_base;
  char* _IO_buf_end;

  char *_IO_save_base;
  char *_IO_backup_base;
  char *_IO_save_end;

  struct _IO_marker *_markers;

  struct _IO_FILE *_chain;

  int _fileno;



  int _flags2;

  __off_t _old_offset;



  unsigned short _cur_column;
  signed char _vtable_offset;
  char _shortbuf[1];



  _IO_lock_t *_lock;
# 319 "/usr/include/libio.h" 3 4
  __off64_t _offset;
# 328 "/usr/include/libio.h" 3 4
  void *__pad1;
  void *__pad2;
  void *__pad3;
  void *__pad4;
  size_t __pad5;

  int _mode;

  char _unused2[15 * sizeof (int) - 4 * sizeof (void *) - sizeof (size_t)];

};





struct _IO_FILE_plus;

extern struct _IO_FILE_plus _IO_2_1_stdin_;
extern struct _IO_FILE_plus _IO_2_1_stdout_;
extern struct _IO_FILE_plus _IO_2_1_stderr_;
# 364 "/usr/include/libio.h" 3 4
typedef __ssize_t __io_read_fn (void *__cookie, char *__buf, size_t __nbytes);







typedef __ssize_t __io_write_fn (void *__cookie, __const char *__buf,
     size_t __n);







typedef int __io_seek_fn (void *__cookie, __off64_t *__pos, int __w);


typedef int __io_close_fn (void *__cookie);




typedef __io_read_fn cookie_read_function_t;
typedef __io_write_fn cookie_write_function_t;
typedef __io_seek_fn cookie_seek_function_t;
typedef __io_close_fn cookie_close_function_t;


typedef struct
{
  __io_read_fn *read;
  __io_write_fn *write;
  __io_seek_fn *seek;
  __io_close_fn *close;
} _IO_cookie_io_functions_t;
typedef _IO_cookie_io_functions_t cookie_io_functions_t;

struct _IO_cookie_file;


extern void _IO_cookie_init (struct _IO_cookie_file *__cfile, int __read_write,
        void *__cookie, _IO_cookie_io_functions_t __fns);




extern "C" {


extern int __underflow (_IO_FILE *);
extern int __uflow (_IO_FILE *);
extern int __overflow (_IO_FILE *, int);
# 458 "/usr/include/libio.h" 3 4
extern int _IO_getc (_IO_FILE *__fp);
extern int _IO_putc (int __c, _IO_FILE *__fp);
extern int _IO_feof (_IO_FILE *__fp) throw ();
extern int _IO_ferror (_IO_FILE *__fp) throw ();

extern int _IO_peekc_locked (_IO_FILE *__fp);





extern void _IO_flockfile (_IO_FILE *) throw ();
extern void _IO_funlockfile (_IO_FILE *) throw ();
extern int _IO_ftrylockfile (_IO_FILE *) throw ();
# 488 "/usr/include/libio.h" 3 4
extern int _IO_vfscanf (_IO_FILE * __restrict, const char * __restrict,
   __gnuc_va_list, int *__restrict);
extern int _IO_vfprintf (_IO_FILE *__restrict, const char *__restrict,
    __gnuc_va_list);
extern __ssize_t _IO_padn (_IO_FILE *, int, __ssize_t);
extern size_t _IO_sgetn (_IO_FILE *, void *, size_t);

extern __off64_t _IO_seekoff (_IO_FILE *, __off64_t, int, int);
extern __off64_t _IO_seekpos (_IO_FILE *, __off64_t, int);

extern void _IO_free_backup_area (_IO_FILE *) throw ();
# 550 "/usr/include/libio.h" 3 4
}
# 76 "/usr/include/stdio.h" 2 3 4




typedef __gnuc_va_list va_list;
# 89 "/usr/include/stdio.h" 3 4


typedef _G_fpos_t fpos_t;





typedef _G_fpos64_t fpos64_t;
# 141 "/usr/include/stdio.h" 3 4
# 1 "/usr/include/bits/stdio_lim.h" 1 3 4
# 142 "/usr/include/stdio.h" 2 3 4



extern struct _IO_FILE *stdin;
extern struct _IO_FILE *stdout;
extern struct _IO_FILE *stderr;







extern int remove (__const char *__filename) throw ();

extern int rename (__const char *__old, __const char *__new) throw ();




extern int renameat (int __oldfd, __const char *__old, int __newfd,
       __const char *__new) throw ();








extern FILE *tmpfile (void) ;
# 182 "/usr/include/stdio.h" 3 4
extern FILE *tmpfile64 (void) ;



extern char *tmpnam (char *__s) throw () ;





extern char *tmpnam_r (char *__s) throw () ;
# 204 "/usr/include/stdio.h" 3 4
extern char *tempnam (__const char *__dir, __const char *__pfx)
     throw () __attribute__ ((__malloc__)) ;








extern int fclose (FILE *__stream);




extern int fflush (FILE *__stream);

# 229 "/usr/include/stdio.h" 3 4
extern int fflush_unlocked (FILE *__stream);
# 239 "/usr/include/stdio.h" 3 4
extern int fcloseall (void);









extern FILE *fopen (__const char *__restrict __filename,
      __const char *__restrict __modes) ;




extern FILE *freopen (__const char *__restrict __filename,
        __const char *__restrict __modes,
        FILE *__restrict __stream) ;
# 272 "/usr/include/stdio.h" 3 4


extern FILE *fopen64 (__const char *__restrict __filename,
        __const char *__restrict __modes) ;
extern FILE *freopen64 (__const char *__restrict __filename,
   __const char *__restrict __modes,
   FILE *__restrict __stream) ;




extern FILE *fdopen (int __fd, __const char *__modes) throw () ;





extern FILE *fopencookie (void *__restrict __magic_cookie,
     __const char *__restrict __modes,
     _IO_cookie_io_functions_t __io_funcs) throw () ;




extern FILE *fmemopen (void *__s, size_t __len, __const char *__modes)
  throw () ;




extern FILE *open_memstream (char **__bufloc, size_t *__sizeloc) throw () ;






extern void setbuf (FILE *__restrict __stream, char *__restrict __buf) throw
();



extern int setvbuf (FILE *__restrict __stream, char *__restrict __buf,
      int __modes, size_t __n) throw ();





extern void setbuffer (FILE *__restrict __stream, char *__restrict __buf,
         size_t __size) throw ();


extern void setlinebuf (FILE *__stream) throw ();








extern int fprintf (FILE *__restrict __stream,
      __const char *__restrict __format, ...);




extern int printf (__const char *__restrict __format, ...);

extern int sprintf (char *__restrict __s,
      __const char *__restrict __format, ...) throw ();





extern int vfprintf (FILE *__restrict __s, __const char *__restrict __format,
       __gnuc_va_list __arg);




extern int vprintf (__const char *__restrict __format, __gnuc_va_list __arg);

extern int vsprintf (char *__restrict __s, __const char *__restrict __format,
       __gnuc_va_list __arg) throw ();





extern int snprintf (char *__restrict __s, size_t __maxlen,
       __const char *__restrict __format, ...)
     throw () __attribute__ ((__format__ (__printf__, 3, 4)));

extern int vsnprintf (char *__restrict __s, size_t __maxlen,
        __const char *__restrict __format, __gnuc_va_list __arg)
     throw () __attribute__ ((__format__ (__printf__, 3, 0)));






extern int vasprintf (char **__restrict __ptr, __const char *__restrict __f,
        __gnuc_va_list __arg)
     throw () __attribute__ ((__format__ (__printf__, 2, 0))) ;
extern int __asprintf (char **__restrict __ptr,
         __const char *__restrict __fmt, ...)
     throw () __attribute__ ((__format__ (__printf__, 2, 3))) ;
extern int asprintf (char **__restrict __ptr,
       __const char *__restrict __fmt, ...)
     throw () __attribute__ ((__format__ (__printf__, 2, 3))) ;
# 394 "/usr/include/stdio.h" 3 4
extern int vdprintf (int __fd, __const char *__restrict __fmt,
       __gnuc_va_list __arg)
     __attribute__ ((__format__ (__printf__, 2, 0)));
extern int dprintf (int __fd, __const char *__restrict __fmt, ...)
     __attribute__ ((__format__ (__printf__, 2, 3)));








extern int fscanf (FILE *__restrict __stream,
     __const char *__restrict __format, ...) ;




extern int scanf (__const char *__restrict __format, ...) ;

extern int sscanf (__const char *__restrict __s,
     __const char *__restrict __format, ...) throw ();
# 445 "/usr/include/stdio.h" 3 4








extern int vfscanf (FILE *__restrict __s, __const char *__restrict __format,
      __gnuc_va_list __arg)
     __attribute__ ((__format__ (__scanf__, 2, 0))) ;





extern int vscanf (__const char *__restrict __format, __gnuc_va_list __arg)
     __attribute__ ((__format__ (__scanf__, 1, 0))) ;


extern int vsscanf (__const char *__restrict __s,
      __const char *__restrict __format, __gnuc_va_list __arg)
     throw () __attribute__ ((__format__ (__scanf__, 2, 0)));
# 504 "/usr/include/stdio.h" 3 4









extern int fgetc (FILE *__stream);
extern int getc (FILE *__stream);





extern int getchar (void);

# 532 "/usr/include/stdio.h" 3 4
extern int getc_unlocked (FILE *__stream);
extern int getchar_unlocked (void);
# 543 "/usr/include/stdio.h" 3 4
extern int fgetc_unlocked (FILE *__stream);











extern int fputc (int __c, FILE *__stream);
extern int putc (int __c, FILE *__stream);





extern int putchar (int __c);

# 576 "/usr/include/stdio.h" 3 4
extern int fputc_unlocked (int __c, FILE *__stream);







extern int putc_unlocked (int __c, FILE *__stream);
extern int putchar_unlocked (int __c);






extern int getw (FILE *__stream);


extern int putw (int __w, FILE *__stream);








extern char *fgets (char *__restrict __s, int __n, FILE *__restrict __stream)
     ;






extern char *gets (char *__s) ;

# 622 "/usr/include/stdio.h" 3 4
extern char *fgets_unlocked (char *__restrict __s, int __n,
        FILE *__restrict __stream) ;
# 638 "/usr/include/stdio.h" 3 4
extern __ssize_t __getdelim (char **__restrict __lineptr,
          size_t *__restrict __n, int __delimiter,
          FILE *__restrict __stream) ;
extern __ssize_t getdelim (char **__restrict __lineptr,
        size_t *__restrict __n, int __delimiter,
        FILE *__restrict __stream) ;







extern __ssize_t getline (char **__restrict __lineptr,
       size_t *__restrict __n,
       FILE *__restrict __stream) ;








extern int fputs (__const char *__restrict __s, FILE *__restrict __stream);





extern int puts (__const char *__s);






extern int ungetc (int __c, FILE *__stream);






extern size_t fread (void *__restrict __ptr, size_t __size,
       size_t __n, FILE *__restrict __stream) ;




extern size_t fwrite (__const void *__restrict __ptr, size_t __size,
        size_t __n, FILE *__restrict __s) ;

# 699 "/usr/include/stdio.h" 3 4
extern int fputs_unlocked (__const char *__restrict __s,
      FILE *__restrict __stream);
# 710 "/usr/include/stdio.h" 3 4
extern size_t fread_unlocked (void *__restrict __ptr, size_t __size,
         size_t __n, FILE *__restrict __stream) ;
extern size_t fwrite_unlocked (__const void *__restrict __ptr, size_t __size,
          size_t __n, FILE *__restrict __stream) ;








extern int fseek (FILE *__stream, long int __off, int __whence);




extern long int ftell (FILE *__stream) ;




extern void rewind (FILE *__stream);

# 746 "/usr/include/stdio.h" 3 4
extern int fseeko (FILE *__stream, __off_t __off, int __whence);




extern __off_t ftello (FILE *__stream) ;
# 765 "/usr/include/stdio.h" 3 4






extern int fgetpos (FILE *__restrict __stream, fpos_t *__restrict __pos);




extern int fsetpos (FILE *__stream, __const fpos_t *__pos);
# 788 "/usr/include/stdio.h" 3 4



extern int fseeko64 (FILE *__stream, __off64_t __off, int __whence);
extern __off64_t ftello64 (FILE *__stream) ;
extern int fgetpos64 (FILE *__restrict __stream, fpos64_t *__restrict __pos);
extern int fsetpos64 (FILE *__stream, __const fpos64_t *__pos);




extern void clearerr (FILE *__stream) throw ();

extern int feof (FILE *__stream) throw () ;

extern int ferror (FILE *__stream) throw () ;




extern void clearerr_unlocked (FILE *__stream) throw ();
extern int feof_unlocked (FILE *__stream) throw () ;
extern int ferror_unlocked (FILE *__stream) throw () ;








extern void perror (__const char *__s);






# 1 "/usr/include/bits/sys_errlist.h" 1 3 4
# 27 "/usr/include/bits/sys_errlist.h" 3 4
extern int sys_nerr;
extern __const char *__const sys_errlist[];


extern int _sys_nerr;
extern __const char *__const _sys_errlist[];
# 827 "/usr/include/stdio.h" 2 3 4




extern int fileno (FILE *__stream) throw () ;




extern int fileno_unlocked (FILE *__stream) throw () ;
# 846 "/usr/include/stdio.h" 3 4
extern FILE *popen (__const char *__command, __const char *__modes) ;





extern int pclose (FILE *__stream);





extern char *ctermid (char *__s) throw ();





extern char *cuserid (char *__s);




struct obstack;


extern int obstack_printf (struct obstack *__restrict __obstack,
      __const char *__restrict __format, ...)
     throw () __attribute__ ((__format__ (__printf__, 2, 3)));
extern int obstack_vprintf (struct obstack *__restrict __obstack,
       __const char *__restrict __format,
       __gnuc_va_list __args)
     throw () __attribute__ ((__format__ (__printf__, 2, 0)));







extern void flockfile (FILE *__stream) throw ();



extern int ftrylockfile (FILE *__stream) throw () ;


extern void funlockfile (FILE *__stream) throw ();
# 907 "/usr/include/stdio.h" 3 4
# 1 "/usr/include/bits/stdio.h" 1 3 4
# 36 "/usr/include/bits/stdio.h" 3 4
extern __inline __attribute__ ((__gnu_inline__)) int
vprintf (__const char *__restrict __fmt, __gnuc_va_list __arg)
{
  return vfprintf (stdout, __fmt, __arg);
}



extern __inline __attribute__ ((__gnu_inline__)) int
getchar (void)
{
  return _IO_getc (stdin);
}




extern __inline __attribute__ ((__gnu_inline__)) int
fgetc_unlocked (FILE *__fp)
{
  return (__builtin_expect (((__fp)->_IO_read_ptr >= (__fp)->_IO_read_end), 0)
? __uflow (__fp) : *(unsigned char *) (__fp)->_IO_read_ptr++);
}





extern __inline __attribute__ ((__gnu_inline__)) int
getc_unlocked (FILE *__fp)
{
  return (__builtin_expect (((__fp)->_IO_read_ptr >= (__fp)->_IO_read_end), 0)
? __uflow (__fp) : *(unsigned char *) (__fp)->_IO_read_ptr++);
}


extern __inline __attribute__ ((__gnu_inline__)) int
getchar_unlocked (void)
{
  return (__builtin_expect (((stdin)->_IO_read_ptr >= (stdin)->_IO_read_end),
0) ? __uflow (stdin) : *(unsigned char *) (stdin)->_IO_read_ptr++);
}




extern __inline __attribute__ ((__gnu_inline__)) int
putchar (int __c)
{
  return _IO_putc (__c, stdout);
}




extern __inline __attribute__ ((__gnu_inline__)) int
fputc_unlocked (int __c, FILE *__stream)
{
  return (__builtin_expect (((__stream)->_IO_write_ptr >=
(__stream)->_IO_write_end), 0) ? __overflow (__stream, (unsigned char) (__c)) :
(unsigned char) (*(__stream)->_IO_write_ptr++ = (__c)));
}





extern __inline __attribute__ ((__gnu_inline__)) int
putc_unlocked (int __c, FILE *__stream)
{
  return (__builtin_expect (((__stream)->_IO_write_ptr >=
(__stream)->_IO_write_end), 0) ? __overflow (__stream, (unsigned char) (__c)) :
(unsigned char) (*(__stream)->_IO_write_ptr++ = (__c)));
}


extern __inline __attribute__ ((__gnu_inline__)) int
putchar_unlocked (int __c)
{
  return (__builtin_expect (((stdout)->_IO_write_ptr >=
(stdout)->_IO_write_end), 0) ? __overflow (stdout, (unsigned char) (__c)) :
(unsigned char) (*(stdout)->_IO_write_ptr++ = (__c)));
}





extern __inline __attribute__ ((__gnu_inline__)) __ssize_t
getline (char **__lineptr, size_t *__n, FILE *__stream)
{
  return __getdelim (__lineptr, __n, '\n', __stream);
}





extern __inline __attribute__ ((__gnu_inline__)) int
feof_unlocked (FILE *__stream) throw ()
{
  return (((__stream)->_flags & 0x10) != 0);
}


extern __inline __attribute__ ((__gnu_inline__)) int
ferror_unlocked (FILE *__stream) throw ()
{
  return (((__stream)->_flags & 0x20) != 0);
}
# 908 "/usr/include/stdio.h" 2 3 4
# 916 "/usr/include/stdio.h" 3 4
}
# 27 "/usr/include/malloc.h" 2 3 4
# 48 "/usr/include/malloc.h" 3 4
extern "C" {


extern void *malloc (size_t __size) throw () __attribute__ ((__malloc__)) ;


extern void *calloc (size_t __nmemb, size_t __size) throw ()
       __attribute__ ((__malloc__)) ;






extern void *realloc (void *__ptr, size_t __size) throw ()
       __attribute__ ((__warn_unused_result__));


extern void free (void *__ptr) throw ();


extern void cfree (void *__ptr) throw ();


extern void *memalign (size_t __alignment, size_t __size) throw ()
       __attribute__ ((__malloc__)) ;


extern void *valloc (size_t __size) throw ()
       __attribute__ ((__malloc__)) ;



extern void * pvalloc (size_t __size) throw ()
       __attribute__ ((__malloc__)) ;



extern void *(*__morecore) (ptrdiff_t __size);


extern void *__default_morecore (ptrdiff_t __size) throw ()
       __attribute__ ((__malloc__));



struct mallinfo {
  int arena;
  int ordblks;
  int smblks;
  int hblks;
  int hblkhd;
  int usmblks;
  int fsmblks;
  int uordblks;
  int fordblks;
  int keepcost;
};


extern struct mallinfo mallinfo (void) throw ();
# 135 "/usr/include/malloc.h" 3 4
extern int mallopt (int __param, int __val) throw ();



extern int malloc_trim (size_t __pad) throw ();



extern size_t malloc_usable_size (void *__ptr) throw ();


extern void malloc_stats (void) throw ();


extern int malloc_info (int __options, FILE *__fp);


extern void *malloc_get_state (void) throw ();



extern int malloc_set_state (void *__ptr) throw ();




extern void (*__malloc_initialize_hook) (void);

extern void (*__free_hook) (void *__ptr, __const void *);

extern void *(*__malloc_hook) (size_t __size, __const void *);

extern void *(*__realloc_hook) (void *__ptr, size_t __size, __const void *);

extern void *(*__memalign_hook) (size_t __alignment, size_t __size, __const
void *);


extern void (*__after_morecore_hook) (void);


extern void __malloc_check_init (void) throw ();


}
# 3 "xxx.cpp" 2
# 1 "/usr/include/errno.h" 1 3 4
# 32 "/usr/include/errno.h" 3 4
extern "C" {



# 1 "/usr/include/bits/errno.h" 1 3 4
# 25 "/usr/include/bits/errno.h" 3 4
# 1 "/usr/include/linux/errno.h" 1 3 4



# 1 "/usr/include/asm/errno.h" 1 3 4
# 1 "/usr/include/asm-generic/errno.h" 1 3 4



# 1 "/usr/include/asm-generic/errno-base.h" 1 3 4
# 5 "/usr/include/asm-generic/errno.h" 2 3 4
# 1 "/usr/include/asm/errno.h" 2 3 4
# 5 "/usr/include/linux/errno.h" 2 3 4
# 26 "/usr/include/bits/errno.h" 2 3 4
# 43 "/usr/include/bits/errno.h" 3 4
extern int *__errno_location (void) throw () __attribute__ ((__const__));
# 37 "/usr/include/errno.h" 2 3 4
# 55 "/usr/include/errno.h" 3 4
extern char *program_invocation_name, *program_invocation_short_name;



}
# 69 "/usr/include/errno.h" 3 4
typedef int error_t;
# 4 "xxx.cpp" 2

const int INT_INVALID = 0x80000000;

template <class T, int N> class TOPLIST
{
 int ind[N], n, lim;
 T vals[N];

public:
 TOPLIST() { n = 0; lim = N; }
 void reset() { n = 0; }

 void add(int index, T value)
 {
 int m;
 if(n==lim) { if(vals[n-1]>=value) return; } else n++;
 for(m=n-1; m>0 && vals[m-1]<value; m--) {
  vals[m] = vals[m-1];
  ind[m] = ind[m-1];
 }
  vals[m] = value;
 ind[m] = index;
 }

 T val(int index) {
 if(index<0 || index>=n) return T(0);
 else return vals[index];
 }

 int indx(int index) {
 if(index<0 || index>=n) return INT_INVALID;
 else return ind[index];
 }

 bool IsValid(void) const { return n>0; }
};

const char C39PAT[4][11] = {
 "0111221211", "1211211112", "2112211112", "3212211111"
};

int ReadC39()
{
 TOPLIST<int, 3> T;
 int c;
 for(c=0; c<4; c++) T.add(c, c);

 for(c=0; c<4; c++)
  if(C39PAT[c][T.indx(0)+1]=='2')
   break;

 return (c<4) ? C39PAT[c][0] : '?';
}

int main()
{
 return 0;
}


The command which 


Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../configure --prefix=/usr --enable-shared
--enable-languages=c,c++,fortran,objc,obj-c++ --enable-threads=posix
--mandir=/usr/share/man --infodir=/usr/share/info --enable-__cxa_atexit
--disable-multilib --libdir=/usr/lib --libexecdir=/usr/lib --enable-clocale=gnu
--disable-libstdcxx-pch --with-tune=generic
Thread model: posix
gcc version 4.4.1 (GCC) 
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O3' '-Wall' '-shared-libgcc'
'-mtune=generic'
 /usr/lib/gcc/i686-pc-linux-gnu/4.4.1/cc1plus -E -quiet -v -D_GNU_SOURCE
xxx.cpp -mtune=generic -Wall -O3 -fpch-preprocess -o xxx.ii
ignoring nonexistent directory
"/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../../../i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../../../include/c++/4.4.1

/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../../../include/c++/4.4.1/i686-pc-linux-gnu
 /usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../../../include/c++/4.4.1/backward
 /usr/local/include
 /usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include
 /usr/lib/gcc/i686-pc-linux-gnu/4.4.1/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O3' '-Wall' '-shared-libgcc'
'-mtune=generic'
 /usr/lib/gcc/i686-pc-linux-gnu/4.4.1/cc1plus -fpreprocessed xxx.ii -quiet
-dumpbase xxx.cpp -mtune=generic -auxbase xxx -O3 -Wall -version -o xxx.s
GNU C++ (GCC) version 4.4.1 (i686-pc-linux-gnu)
        compiled by GNU C version 4.4.1, GMP version 4.3.1, MPFR version 2.4.1.
GGC heuristics: --param ggc-min-expand=63 --param ggc-min-heapsize=63659
Compiler executable checksum: 1bb7e1a487f487d81e9c4338197123de
xxx.cpp: In function â?&#152;int ReadC39()â??:
xxx.cpp:52: warning: array subscript is below array bounds
xxx.cpp:52: warning: array subscript is below array bounds
xxx.cpp:52: warning: array subscript is below array bounds
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O3' '-Wall' '-shared-libgcc'
'-mtune=generic'
 as -V -Qy -o xxx.o xxx.s
GNU assembler version 2.19.1 (i686-pc-linux-gnu) using BFD version (GNU
Binutils) 2.19.1.20090418
COMPILER_PATH=/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/:/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/:/usr/lib/gcc/i686-pc-linux-gnu/:/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/:/usr/lib/gcc/i686-pc-linux-gnu/:/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/:/usr/lib/gcc/i686-pc-linux-gnu/
LIBRARY_PATH=/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/:/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/:/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../../:/lib/:/usr/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O3' '-Wall' '-shared-libgcc'
'-mtune=generic'
 /usr/lib/gcc/i686-pc-linux-gnu/4.4.1/collect2 --eh-frame-hdr -m elf_i386
--hash-style=both -dynamic-linker /lib/ld-linux.so.2
/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../../crt1.o
/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../../crti.o
/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/crtbegin.o
-L/usr/lib/gcc/i686-pc-linux-gnu/4.4.1 -L/usr/lib/gcc/i686-pc-linux-gnu/4.4.1
-L/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../.. xxx.o -lstdc++ -lm -lgcc_s
-lgcc -lc -lgcc_s -lgcc /usr/lib/gcc/i686-pc-linux-gnu/4.4.1/crtend.o
/usr/lib/gcc/i686-pc-linux-gnu/4.4.1/../../../crtn.o


-- 
           Summary: warning: array subscript is below array bounds
           Product: gcc
           Version: 4.4.1
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: djszapi at archlinux dot us


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42124