pub const Fixups = struct {
    /// The key is the mut token (`var`/`const`) of the variable declaration
    /// that should have a `_ = foo;` inserted afterwards.
    unused_var_decls: std.AutoHashMapUnmanaged(Ast.TokenIndex, void) = .empty,
    /// The functions in this unordered set of AST fn decl nodes will render
    /// with a function body of `@trap()` instead, with all parameters
    /// discarded.
    gut_functions: std.AutoHashMapUnmanaged(Ast.Node.Index, void) = .empty,
    /// These global declarations will be omitted.
    omit_nodes: std.AutoHashMapUnmanaged(Ast.Node.Index, void) = .empty,
    /// These expressions will be replaced with the string value.
    replace_nodes_with_string: std.AutoHashMapUnmanaged(Ast.Node.Index, []const u8) = .empty,
    /// The string value will be inserted directly after the node.
    append_string_after_node: std.AutoHashMapUnmanaged(Ast.Node.Index, []const u8) = .empty,
    /// These nodes will be replaced with a different node.
    replace_nodes_with_node: std.AutoHashMapUnmanaged(Ast.Node.Index, Ast.Node.Index) = .empty,
    /// Change all identifier names matching the key to be value instead.
    rename_identifiers: std.StringArrayHashMapUnmanaged([]const u8) = .empty,

    /// All `@import` builtin calls which refer to a file path will be prefixed
    /// with this path.
    rebase_imported_paths: ?[]const u8 = null,

    pub fn count(f: Fixups) usize {
        return f.unused_var_decls.count() +
            f.gut_functions.count() +
            f.omit_nodes.count() +
            f.replace_nodes_with_string.count() +
            f.append_string_after_node.count() +
            f.replace_nodes_with_node.count() +
            f.rename_identifiers.count() +
            @intFromBool(f.rebase_imported_paths != null);
    }

    pub fn clearRetainingCapacity(f: *Fixups) void {
        f.unused_var_decls.clearRetainingCapacity();
        f.gut_functions.clearRetainingCapacity();
        f.omit_nodes.clearRetainingCapacity();
        f.replace_nodes_with_string.clearRetainingCapacity();
        f.append_string_after_node.clearRetainingCapacity();
        f.replace_nodes_with_node.clearRetainingCapacity();
        f.rename_identifiers.clearRetainingCapacity();

        f.rebase_imported_paths = null;
    }

    pub fn deinit(f: *Fixups, gpa: Allocator) void {
        f.unused_var_decls.deinit(gpa);
        f.gut_functions.deinit(gpa);
        f.omit_nodes.deinit(gpa);
        f.replace_nodes_with_string.deinit(gpa);
        f.append_string_after_node.deinit(gpa);
        f.replace_nodes_with_node.deinit(gpa);
        f.rename_identifiers.deinit(gpa);
        f.* = undefined;
    }
}