Wireshark · Wireshark-dev: Re: [Wireshark-dev] buildbot failure in Wireshark (development) on OSX

[Jeff Morriss <jeff.morriss.ws@xxxxxxxxx>]

Graham Bloice wrote:
> Any idea why the OSX compilers are complaining about this code in 
> packet-dnp.c:
>
>  if (!header_only || al_objq_index > 0) {
>     start_offset = offset;
>     for (item_num = 0; item_num < num_items; item_num++)
>     {
>       /* Create Point item and Process Index */
>       if (AL_OBJQL_IDX_NI <= al_objq_index && al_objq_index <= 
> AL_OBJQL_IDX_4O)   <---------- Error here

[...]

> The reported error is:
>
> packet-dnp.c: In function 'dnp3_al_process_object':
> packet-dnp.c:1566: warning: comparison is always true due to limited range of data type
>
> The variable (al_objq_index) is three bits so has a value between 0 and 
> 7 and the constants are enumerations of the values.  AL_OBJQL_IDX_NI is 
> 0 and AL_OBJQL_IDX_4O is 3.  I suspect that the following if() might 
> also error out as it just checks for a different range of values (4-6).

The problem is that al_objq_index is a guint8 and AL_OBJQL_IDX_NI is 
0x0.  Since an unsigned variable can't go negative, al_objq_index is 
ALWAYS greater than AL_OBJQL_IDX_NI (0).

From quickly looking at the code, I'd guess that this comparison can 
simply be removed.