nix --help: Display help using lowdown instead of man

Fixes #4476.
Fixes #5231.

1 files changed, 6 insertions, 2 deletions

diff --git a/src/libutil/args.hh b/src/libutil/args.hh
index c08ba8abd..22c94b501 100644
--- a/src/libutil/args.hh
+++ b/src/libutil/args.hh
@@ -12,6 +12,8 @@ namespace nix {
 
 enum HashType : char;
 
+class MultiCommand;
+
 class Args
 {
 public:
@@ -169,11 +171,13 @@ public:
     virtual nlohmann::json toJSON();
 
     friend class MultiCommand;
+
+    MultiCommand * parent = nullptr;
 };
 
 /* A command is an argument parser that can be executed by calling its
    run() method. */
-struct Command : virtual Args
+struct Command : virtual public Args
 {
     friend class MultiCommand;
 
@@ -193,7 +197,7 @@ typedef std::map<std::string, std::function<ref<Command>()>> Commands;
 
 /* An argument parser that supports multiple subcommands,
    i.e. ‘<command> <subcommand>’. */
-class MultiCommand : virtual Args
+class MultiCommand : virtual public Args
 {
 public:
     Commands commands;