I just ran into a compile error on code that has been just fine for 18 years. The only reason I'm compiling it is just to be sure on a new computer/Linux install.

With gcc 4.8.3 I do not get the warnings, with gcc 13.3.0 I get the warnings shown below the code below. The char string being converted is hex, data returned from a solar inverter.

And like I said it's been fine and I suspect the program will run fine just cannot fully test it yet until data collect is moved to this new server.


*--------------------------------------------------------------------------
    szCvrtLong
    Converts a 4 char string to a long.
----------------------------------------------------------------------------*/
unsigned long szCvrtLong(char *Buffer)
{
    unsigned char cValue[4];
    unsigned long *value = 0;

    if (! bSwapEndian) {
        cValue[0] = Buffer[aParam4] & 0xff;
        cValue[1] = Buffer[aParam3] & 0xff;
        cValue[2] = Buffer[aParam2] & 0xff;
        cValue[3] = Buffer[aParam1] & 0xff;
    } else {
        cValue[0] = Buffer[aParam1] & 0xff;
        cValue[1] = Buffer[aParam2] & 0xff;
        cValue[2] = Buffer[aParam3] & 0xff;
        cValue[3] = Buffer[aParam4] & 0xff;
    }

    value = (unsigned long *)cValue;
    if (bVerbose) fprintf(stderr, "szCvrtLong   %12lu 0x%02x%02x%02x%02x\n",*value & 0xffffffff,cValue[3],cValue[2],cValue[1],cValue[0]);

    return(*value & 0xffffffff);
}

-----------

comm.c: In function 'szCvrtLong.constprop':
comm.c:1906:77: warning: array subscript 'long unsigned int[0]' is partly outside array bounds of 'unsigned char[4]' [-Warray-bounds=]
 1906 |     if (bVerbose) fprintf(stderr, "szCvrtLong   %12lu 0x%02x%02x%02x%02x\n",*value & 0xffffffff,cValue[3],cValue[2],cValue[1],cValue[0]);
      |                                                                             ^~~~~~
comm.c:1890:19: note: object 'cValue' of size 4
 1890 |     unsigned char cValue[4];
      |                   ^~~~~~
comm.c:1908:12: warning: array subscript 'long unsigned int[0]' is partly outside array bounds of 'unsigned char[4]' [-Warray-bounds=]
 1908 |     return(*value & 0xffffffff);
      |            ^~~~~~
comm.c:1890:19: note: object 'cValue' of size 4
 1890 |     unsigned char cValue[4];
      |                   ^~~~~~