020 nested branch shadowing

// FIXED: Nested same-branch name no longer causes Zig shadowing error
//
// Previously: When the same branch name (e.g., `done`) appeared at multiple nesting
// levels, the emitter generated captures even when they weren't used.
//
// Fix: Now only captures bindings that are actually referenced in the code.

~import "$std/control"

const std = @import("std");

const Resource = struct {
    id: usize,
    data: [64]u8,
};

~event create { id: usize }
| created { r: *Resource[active!] }

~proc create {
    const r = std.heap.page_allocator.create(Resource) catch unreachable;
    r.* = Resource{ .id = id, .data = undefined };
    return .{ .created = .{ .r = r } };
}

~event work { r: *Resource[active] }
| done {}

~proc work {
    r.data[0] +%= 1;
    return .{ .done = .{} };
}

~event destroy { r: *Resource[!active] }
| destroyed {}

~proc destroy {
    std.heap.page_allocator.destroy(r);
    return .{ .destroyed = .{} };
}

~event run_one { id: usize }
| finished {}

~run_one = create(id: id)
| created r |>
    work(r: r.r)
    | done |>
        work(r: r.r)
        | done |>
            work(r: r.r)
            | done |>
                work(r: r.r)
                | done |>
                    work(r: r.r)
                    | done |>
                        destroy(r: r.r)
                        | destroyed |> finished {}

~for(0..10)
| each _ |>
    run_one(id: 0)
    | finished |> _
| done |> _

pub fn main() void {}