I guess this is a bug?

[Random D user via Digitalmars-d-learn]

or is it some obscure feature conflict?

struct Foo
{
    this( float x_, float y_ )
    {
        // option A
        //x = x_;
        //y = y_;
        // option B
        v[0] = x_;
        v[1] = y_;
    }

    union
    {
        struct
        {
            float x = 0;
            float y = 0;
        }
        float[2] v;
    }
}

struct Bar
{
    Foo foo = Foo( 1, 2 );
}

Bar bar;
Bar baz = bar.init;

printf( "bar: %f, %f\n", bar.foo.x, bar.foo.y );
printf( "baz: %f, %f\n", baz.foo.x, baz.foo.y );
-------------------------------------------------
prints (with option B):
bar: 0.000000, 0.000000   // BUG??
baz: 1.000000, 2.000000

prints (with option A):
bar: 1.000000, 2.000000
baz: 1.000000, 2.000000
-------------------------------------------------
Luckily the option A works as I expected and is good enough for 
me...