create

pub fn create(
    graph: *Graph,
    root: Cache.Path,
    available_deps: AvailableDeps,
) error{OutOfMemory}!*Build {
    const arena = graph.arena;

    const b = try arena.create(Build);
    b.* = .{
        .graph = graph,
        .root = root,
        .invalid_user_input = false,
        .allocator = arena,
        .user_input_options = .empty,
        .top_level_steps = .{},
        .default_step = undefined,
        .install_tls = .{
            .step = .init(.{
                .tag = .top_level,
                .name = "install",
                .owner = b,
            }),
            .description = "Copy build artifacts to prefix path",
        },
        .uninstall_tls = .{
            .step = .init(.{
                .tag = .top_level,
                .name = "uninstall",
                .owner = b,
            }),
            .description = "Remove build artifacts from prefix path",
        },
        .modules = .empty,
        .named_writefiles = .empty,
        .named_lazy_paths = .empty,
        .pkg_hash = "",
        .available_deps = available_deps,
    };
    try b.top_level_steps.put(arena, b.install_tls.step.name, &b.install_tls);
    try b.top_level_steps.put(arena, b.uninstall_tls.step.name, &b.uninstall_tls);
    b.default_step = &b.install_tls.step;
    return b;
}