From a6adaab2bcb87ce5f71ad6c78dd6c03c920f159a Mon Sep 17 00:00:00 2001
From: Raito Bezarius <raito@lix.systems>
Date: Fri, 28 Mar 2025 21:08:02 +0100
Subject: [PATCH] libmain: undo accidental lix command stabilization

When external subcommand support landed, the `lix` binary gave
accidental access to nix3 CLI as well.

This was not the intended effect of this feature, we want to keep `lix`
as a namespace for a new redesign of the CLI (that has not started yet),
while giving that namespace for external subcommands.

To this end, we sever the nix3 CLI connection for the `lix` binary.

Fixes fj#508.

Change-Id: I13a0748bcbf87343c8e0e89439bd4af3a0ac3118
Signed-off-by: Raito Bezarius <raito@lix.systems>
---
 lix/libmain/shared.cc |  9 ++++-
 lix/nix/main.cc       | 76 +++++++++++++++++++++++--------------------
 2 files changed, 48 insertions(+), 37 deletions(-)

diff --git a/lix/libmain/shared.cc b/lix/libmain/shared.cc
index 184c6bec9..04cf476f7 100644
--- a/lix/libmain/shared.cc
+++ b/lix/libmain/shared.cc
@@ -312,6 +312,10 @@ int handleExceptions(const std::string & programName, std::function<void()> fun)
     ReceiveInterrupts receiveInterrupts; // FIXME: need better place for this
 
     ErrorInfo::programName = baseNameOf(programName);
+    /* Lix command line is not yet stabilized.
+     * Explain that it is experimental and reserved for custom subcommands for now.
+     * */
+    bool onlyForSubcommands = ErrorInfo::programName == "lix";
 
     std::string error = ANSI_RED "error:" ANSI_NORMAL " ";
     try {
@@ -320,7 +324,10 @@ int handleExceptions(const std::string & programName, std::function<void()> fun)
         return e.status;
     } catch (UsageError & e) {
         logError(e.info());
-        printError("Try '%1% --help' for more information.", programName);
+        if (onlyForSubcommands)
+            printError("'%1%' is reserved for external subcommands, is your subcommand available in the PATH?", programName);
+        else
+            printError("Try '%1% --help' for more information.", programName);
         return 1;
     } catch (BaseError & e) {
         logError(e.info());
diff --git a/lix/nix/main.cc b/lix/nix/main.cc
index b22f13217..819da09bb 100644
--- a/lix/nix/main.cc
+++ b/lix/nix/main.cc
@@ -202,7 +202,9 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs, virtual RootArgs
     AsyncIoRoot & aio() override { return aio_; }
 
     NixArgs(const std::string & programName, AsyncIoRoot & aio)
-        : MultiCommand(CommandRegistry::getCommandsFor({}), true)
+        /* NOTE: when using lix, the command map is empty as `lix-command` is not stabilized neither designed.
+         * `lix` is only used for external commands. */
+        : MultiCommand(programName == "lix" ? CommandMap() : CommandRegistry::getCommandsFor({}), programName == "lix")
         , MixCommonArgs(programName)
         , aio_(aio)
     {
@@ -213,45 +215,47 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs, virtual RootArgs
         categories[catUtility] = "Utility/scripting commands";
         categories[catNixInstallation] = "Commands for upgrading or troubleshooting your Nix installation";
 
-        addFlag({
-            .longName = "help",
-            .description = "Show usage information.",
-            .category = miscCategory,
-            .handler = {[this]() { this->helpRequested = true; }},
-        });
+        if (programName != "lix") {
+            addFlag({
+                .longName = "help",
+                .description = "Show usage information.",
+                .category = miscCategory,
+                .handler = {[this]() { this->helpRequested = true; }},
+            });
 
-        addFlag({
-            .longName = "print-build-logs",
-            .shortName = 'L',
-            .description = "Print full build logs on standard error.",
-            .category = loggingCategory,
-            .handler = {[&]() { logger->setPrintBuildLogs(true); }},
-            .experimentalFeature = Xp::NixCommand,
-        });
+            addFlag({
+                .longName = "print-build-logs",
+                .shortName = 'L',
+                .description = "Print full build logs on standard error.",
+                .category = loggingCategory,
+                .handler = {[&]() { logger->setPrintBuildLogs(true); }},
+                .experimentalFeature = Xp::NixCommand,
+            });
 
-        addFlag({
-            .longName = "version",
-            .description = "Show version information.",
-            .category = miscCategory,
-            .handler = {[&]() { showVersion = true; }},
-        });
+            addFlag({
+                .longName = "version",
+                .description = "Show version information.",
+                .category = miscCategory,
+                .handler = {[&]() { showVersion = true; }},
+            });
 
-        addFlag({
-            .longName = "offline",
-            .aliases = {"no-net"}, // FIXME: remove
-            .description = "Disable substituters and consider all previously downloaded files up-to-date.",
-            .category = miscCategory,
-            .handler = {[&]() { useNet = false; }},
-            .experimentalFeature = Xp::NixCommand,
-        });
+            addFlag({
+                .longName = "offline",
+                .aliases = {"no-net"}, // FIXME: remove
+                .description = "Disable substituters and consider all previously downloaded files up-to-date.",
+                .category = miscCategory,
+                .handler = {[&]() { useNet = false; }},
+                .experimentalFeature = Xp::NixCommand,
+            });
 
-        addFlag({
-            .longName = "refresh",
-            .description = "Consider all previously downloaded files out-of-date.",
-            .category = miscCategory,
-            .handler = {[&]() { refresh = true; }},
-            .experimentalFeature = Xp::NixCommand,
-        });
+            addFlag({
+                .longName = "refresh",
+                .description = "Consider all previously downloaded files out-of-date.",
+                .category = miscCategory,
+                .handler = {[&]() { refresh = true; }},
+                .experimentalFeature = Xp::NixCommand,
+            });
+        }
     }
 
     std::map<std::string, std::vector<std::string>> aliases = {