It seems pure ain't so pure after all

[Tommi]

import std.stdio;

int pow2(int val) pure
{
    if (__ctfe)
        return 6;
    else
        return val * val;
}

void main()
{
           assert(pow2(3) == 9);
    static assert(pow2(3) == 6);

    writeln("9 = 6 ... I knew it! '6' was faking it all along");
    readln();
}