Wise monks, what could be wrong in:

for $i (1..100) {
    $r=C($i);
    print $r."\n"
}
use Inline C => <<'C_CODE';
int C (int i) {
    Inline_Stack_Vars;
    return i;
    Inline_Stack_Void;
}
C_CODE
[download]

to produce:

... 
94
95
96
97
98
99
100
Segmentation fault
[download]

I have also tryied the following version of C_CODE:

SV* C (SV* param) {
    Inline_Stack_Vars;
    int i = atoi(SvPV(Inline_Stack_Item(0), PL_na));
    return newSVpvf("%i",i);
    Inline_Stack_Void;
}
[download]

getting:

1
0
0
Segmentation fault
[download]

But if I declare SV* C (SV* param,...) it seems to work...