main return value, struct padding

[Steven Schveighoffer]

"bearophile" wrote
>I post this here, but if later I see it fit I may post something in the 
>main D group too.
>
> D allows to have the main() function of type void too. In such case I'd 
> like the program return 0 by default. If people agrees, this can become a 
> feature request.

A test:
[steves at localhost testing]$ cat testmainreturn.d
void main()
{
    return 1;
}
[steves at localhost testing]$ cat testmainreturn2.d
void main()
{
}
[steves at localhost testing]$ dmd testmainreturn.d
[steves at localhost testing]$ dmd testmainreturn2.d
[steves at localhost testing]$ ./testmainreturn
[steves at localhost testing]$ echo $?
1
[steves at localhost testing]$ ./testmainreturn2
[steves at localhost testing]$ echo $?
0
[steves at localhost testing]$ dmd | grep "Digital Mars D"
Digital Mars D Compiler v1.038
[steves at localhost testing]$

disassembly:
[steves at localhost testing]$ obj2asm testmainreturn.o
...
_Dmain:
                push    EBP
                mov     EBP,ESP
                mov     EAX,1
                pop     EBP
                ret
.text._Dmain    ends
...
[steves at localhost testing]$ obj2asm testmainreturn2.o
...
_Dmain:
                push    EBP
                mov     EBP,ESP
                xor     EAX,EAX
                pop     EBP
                ret
.text._Dmain    ends
...

So it appears it returns 0 unless you return something else (!)

-Steve