Function that calculates in compile time when it can

[Philippe Sigaud]

On Mon, Aug 6, 2012 at 6:17 PM, Minas Mina <minas_mina1990 at hotmail.co.uk> wrote:

> I found this:
>
> real sin(real x) @safe pure nothrow; /* intrinsic */

> I don't see anything about ctfe. Maybe I didn't understand well
> and sin is not evaluated at compile time. Can someone clarify
> this?

Oh, I thought they were implemented as polynomial approximations.

Never mind, you can test it with any function:

int foo(int i)
{
    if (__ctfe)
    {
        pragma(msg, "CT");
        return -1;
    }
    else
        return 1;
}

void main()
{
    auto i = foo(0);
    static j = foo(0);
    writeln(i); // 1
    writeln(j); // -1
}

So, auto i doesn't provoke CT-evaluation (else it'd be -1).