bearophile Wrote:
> A little quiz for people here: guess the output of this little D2 program (it
> compiles correctly and doesn't crash at run time, so it's a fair question):
>
>
> import std.typecons: tuple;
> import std.c.stdio: printf;
>
> auto foo() {
> printf("foo\n");
> return tuple(1, 2);
> }
>
> void main() {
> foreach (x; foo().tupleof)
> printf("%d\n", x);
> }
Starting from main. As we are performing a foreach over a tuple this will need
to happen at compilation. As their are many bugs with compile time foreach I
would think this code evaluates to nothing and thus the program prints nothing.
However if that is working then I would expect foo() to be executed at
compile-time which would mean 'foo' might be printed during compilation. As
tupleof is supposed to return a type tuple, I'm unsure what gibberish printing
it as a decimal would do.
The other likely possibility is that the foreach is unrolled into code like:
x = foo().tupleof[0]
print...
x = foo().tupleof[1]
print...
where .tupleof is some other fancy runtime thing. In this case you would get
foo\nnumber\nfoo\nnumber...
------
So yeah, from that code I have no idea what it is supposed to do. But I am not
surprised by its behavior.
