Move some options into a misc category

This unclutters the per-command options a bit by moving out some
global options.

src/libcmd/command.cc

@@ -88,7 +88,8 @@ EvalCommand::EvalCommand()
 {
     addFlag({
         .longName = "debugger",
-        .description = "start an interactive environment if evaluation fails",
+        .description = "Start an interactive environment if evaluation fails.",
+        .category = MixEvalArgs::category,
         .handler = {&startReplOnEvalErrors, true},
     });
 }

src/libcmd/common-eval-args.cc

@@ -13,8 +13,6 @@ namespace nix {
 
 MixEvalArgs::MixEvalArgs()
 {
-    auto category = "Common evaluation options";
-
     addFlag({
         .longName = "arg",
         .description = "Pass the value *expr* as the argument *name* to Nix functions.",

src/libcmd/common-eval-args.hh

@@ -10,6 +10,8 @@ class Bindings;
 
 struct MixEvalArgs : virtual Args
 {
+    static constexpr auto category = "Common evaluation options";
+
     MixEvalArgs();
 
     Bindings * getAutoArgs(EvalState & state);

src/libmain/common-args.cc

@@ -32,6 +32,7 @@ MixCommonArgs::MixCommonArgs(const std::string & programName)
     addFlag({
         .longName = "option",
         .description = "Set the Nix configuration setting *name* to *value* (overriding `nix.conf`).",
+        .category = miscCategory,
         .labels = {"name", "value"},
         .handler = {[](std::string name, std::string value) {
             try {

src/libmain/common-args.hh

@@ -6,6 +6,7 @@ namespace nix {
 
 //static constexpr auto commonArgsCategory = "Miscellaneous common options";
 static constexpr auto loggingCategory = "Logging-related options";
+static constexpr auto miscCategory = "Miscellaneous global options";
 
 class MixCommonArgs : public virtual Args
 {

src/nix/main.cc

@@ -74,6 +74,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
         addFlag({
             .longName = "help",
             .description = "Show usage information.",
+            .category = miscCategory,
             .handler = {[&]() { throw HelpRequested(); }},
         });
 
@@ -88,6 +89,7 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
         addFlag({
             .longName = "version",
             .description = "Show version information.",
+            .category = miscCategory,
             .handler = {[&]() { showVersion = true; }},
         });
 
@@ -95,12 +97,14 @@ struct NixArgs : virtual MultiCommand, virtual MixCommonArgs
             .longName = "offline",
             .aliases = {"no-net"}, // FIXME: remove
             .description = "Disable substituters and consider all previously downloaded files up-to-date.",
+            .category = miscCategory,
             .handler = {[&]() { useNet = false; }},
         });
 
         addFlag({
             .longName = "refresh",
             .description = "Consider all previously downloaded files out-of-date.",
+            .category = miscCategory,
             .handler = {[&]() { refresh = true; }},
         });
     }