// issue-0028: Feature — make protocol boxes assignable to an optional
// type so callers can spell "no GPU bound" as `?GPU = null` instead of
// the verbose `T = ---; has_T: bool` pattern.
//
// ── Current pattern (verbose) ─────────────────────────────────────────────
//
//   gpu: GPU = ---;
//   has_gpu: bool = false;
//   ...
//   if self.has_gpu { self.gpu.create_shader(...); }
//
// ── Proposed pattern ──────────────────────────────────────────────────────
//
//   gpu: ?GPU = null;
//   ...
//   if self.gpu != null { self.gpu.create_shader(...); }
//
// ── Where the verbose pattern lives today ─────────────────────────────────
//
// library/modules/ui/renderer.sx     — UIRenderer.gpu + has_gpu
// library/modules/ui/glyph_cache.sx  — GlyphCache.gpu + has_gpu
// library/modules/ui/pipeline.sx     — UIPipeline.gpu + has_gpu (+ set_gpu)
// library/modules/platform/uikit.sx  — UIKitPlatform.frame_closure +
//                                       has_frame_closure (Closure type,
//                                       same pattern but on a closure)
//
// ── Implementation sketch ─────────────────────────────────────────────────
//
// Protocol boxes are 2-pointer structs ({vtable, ctx} or {ctx, fn_ptrs...}
// depending on the inline-vs-vtable shape — see src/ir/lower.zig
// `buildProtocolValue` ~7800-7869). `?T` for these can use `vtable_ptr ==
// null` (or `ctx == null`, depending on layout choice) as the "none"
// sentinel — no extra storage needed. This matches the existing
// optional-closure handling at src/ir/emit_llvm.zig where `?Closure` uses
// `fn_ptr == null` as none.
//
// Approach:
//   1. Extend `?T` type construction to accept T being a protocol type.
//      Files: src/ir/types.zig + src/ir/lower.zig (type-resolution).
//   2. Implement `optional_wrap` / `optional_unwrap` /
//      `optional_has_value` for protocol-typed payloads in
//      src/ir/emit_llvm.zig — model after the closure-optional path.
//   3. Keep the existing `T = ---; has_T: bool` pattern working — the
//      new `?T` is additive, not a replacement. Don't churn existing
//      files (uikit.sx's frame_closure pattern stays).
//
// ── Syntax constraint ─────────────────────────────────────────────────────
//
// `?T` syntax already exists for primitives + pointers. Extending to
// protocols is a type-system change; no new surface syntax needed.

#import "modules/std.sx";
main :: () -> s32 { 0; }