compiling SYNwall/SYNgate I get warnings about unused labels. I can ignore them with "-Wno-unused-label" but is there a reason to keep unused labels into the code? Thanks
yes, there is (or better, there was) but may be I changed my mind on that: the reason to keep them was to have the source structure ready to "implement" new/different features/behavior, at least during the development phase. But actually, right now may be it's better to have a clean compilation output, to spot out possible new warnings in an easier way....so remove them may be it's a good idea
mainly is for readability of code: going without "goto", as you already pointed out, means to have a mess in terms of if/then/else constructs. Let's say that, if used for specific reasons, the "goto" is not to ban at all in code. In this case, for example as an exit condition of a function, it is not only acceptable, but even suggested. In terms of performance it probably does not change a lot. And yes, you are right: once compiled, even the nested if/then/else are most probably "resolved" with jumps statement by the optimizer
With gcc 9.3:
if ( a < 100) {
if ( a < 90 ){
if ( a < 80 ) {
return 1;
}
}
}
return 0;the following is produced
push rbp
mov rbp, rsp
mov DWORD PTR [rbp-4], edi
cmp DWORD PTR [rbp-4], 99
jg .L2
cmp DWORD PTR [rbp-4], 89
jg .L2
cmp DWORD PTR [rbp-4], 79
jg .L2
mov eax, 1
jmp .L3
.L2:
mov eax, 0
.L3:
pop rbp
retAs you can see tge jg just replicate a goto-like behavior
About "pragma" directives: it seems "diagnostic pragmas" have been introduced in gcc 4.2.4 (May 2008).
I managed to ignore warnings at function level (
I managed to ignore warnings at function level (
#pragma GCC diagnostic ignored "-Wunused-label") with gcc 4.4.7 but I don't have lab systems to easily install older gcc versions.
it sounds great! Thank you! I think we can use this at this point, since the implementation is old enough. In this way we can just ignore the warning in the specific portion of codes. Just as a reminder, we can add a comment there saying that in case of older GCC versions, the directives can just be removed (if they are causing errors)
UDP ports 123 and 53 are hard-coded into "check_udp_blacklist" function. A new parameter to overwrite the default should not be so useful but I think this behavior should be reported into README file (I needed to query an internal dns server on the same SYNwall mesh network)
for sure in the README it should be documented. I'm thinking about the parameter...