From d72ee91d07a286b18862235792326297199a0d75 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 1 Mar 2024 14:14:14 +0100
Subject: [PATCH] Clean up --arg processing

---
 src/libcmd/common-eval-args.cc | 20 ++++++++++++--------
 src/libcmd/common-eval-args.hh |  7 ++++++-
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/src/libcmd/common-eval-args.cc b/src/libcmd/common-eval-args.cc
index 444ff81c9..ed2c126a4 100644
--- a/src/libcmd/common-eval-args.cc
+++ b/src/libcmd/common-eval-args.cc
@@ -20,7 +20,7 @@ MixEvalArgs::MixEvalArgs()
         .description = "Pass the value *expr* as the argument *name* to Nix functions.",
         .category = category,
         .labels = {"name", "expr"},
-        .handler = {[&](std::string name, std::string expr) { autoArgs[name] = 'E' + expr; }}
+        .handler = {[&](std::string name, std::string expr) { autoArgs.insert_or_assign(name, AutoArg{AutoArgExpr(expr)}); }}
     });
 
     addFlag({
@@ -28,7 +28,7 @@ MixEvalArgs::MixEvalArgs()
         .description = "Pass the string *string* as the argument *name* to Nix functions.",
         .category = category,
         .labels = {"name", "string"},
-        .handler = {[&](std::string name, std::string s) { autoArgs[name] = 'S' + s; }},
+        .handler = {[&](std::string name, std::string s) { autoArgs.insert_or_assign(name, AutoArg{AutoArgString(s)}); }},
     });
 
     addFlag({
@@ -154,13 +154,17 @@ MixEvalArgs::MixEvalArgs()
 Bindings * MixEvalArgs::getAutoArgs(EvalState & state)
 {
     auto res = state.buildBindings(autoArgs.size());
-    for (auto & i : autoArgs) {
+    for (auto & [name, arg] : autoArgs) {
         auto v = state.allocValue();
-        if (i.second[0] == 'E')
-            state.mkThunk_(*v, state.parseExprFromString(i.second.substr(1), state.rootPath(".")));
-        else
-            v->mkString(((std::string_view) i.second).substr(1));
-        res.insert(state.symbols.create(i.first), v);
+        std::visit(overloaded {
+            [&](const AutoArgExpr & arg) {
+                state.mkThunk_(*v, state.parseExprFromString(arg.expr, state.rootPath(".")));
+            },
+            [&](const AutoArgString & arg) {
+                v->mkString(arg.s);
+            }
+        }, arg);
+        res.insert(state.symbols.create(name), v);
     }
     return res.finish();
 }
diff --git a/src/libcmd/common-eval-args.hh b/src/libcmd/common-eval-args.hh
index 2eb63e15d..2e2f18385 100644
--- a/src/libcmd/common-eval-args.hh
+++ b/src/libcmd/common-eval-args.hh
@@ -26,7 +26,12 @@ struct MixEvalArgs : virtual Args, virtual MixRepair
     std::optional<std::string> evalStoreUrl;
 
 private:
-    std::map<std::string, std::string> autoArgs;
+    struct AutoArgExpr { std::string expr; };
+    struct AutoArgString { std::string s; };
+
+    using AutoArg = std::variant<AutoArgExpr, AutoArgString>;
+
+    std::map<std::string, AutoArg> autoArgs;
 };
 
 SourcePath lookupFileArg(EvalState & state, std::string_view s, const Path * baseDir = nullptr);