// issue-0004: scalar-to-vector conversion when all optional struct fields are null
//
// When a struct has multiple ?f32 fields and ALL are set to null simultaneously,
// passing that struct to a virtual function call triggers:
//   "error: scalar-to-vector conversion failed"
//
// Setting at least one field to a concrete value works fine.

#import "modules/std.sx";

ProposedSize :: struct {
    width: ?f32;
    height: ?f32;
}

Sizable :: protocol {
    size :: (proposal: ProposedSize) -> f32;
}

Widget :: struct {}

impl Sizable for Widget {
    size :: (self: *Widget, proposal: ProposedSize) -> f32 {
        w := if pw := proposal.width { pw; } else { 100.0; };
        h := if ph := proposal.height { ph; } else { 100.0; };
        w + h;
    }
}

main :: () -> void {
    w := Widget.{};
    s : Sizable = w;

    // These work:
    r1 := s.size(ProposedSize.{ width = 50.0, height = null });
    print("r1 = {}\n", r1);
    r2 := s.size(ProposedSize.{ width = null, height = 50.0 });
    print("r2 = {}\n", r2);

    // This fails with "scalar-to-vector conversion failed":
    r3 := s.size(ProposedSize.{ width = null, height = null });
    print("r3 = {}\n", r3);
}