From 0acd783190418af514b363685e010195ea7260bc Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Tue, 20 Feb 2024 15:22:15 +0100
Subject: [PATCH] Don't send settings that depend on disabled experimental
 features to the daemon

This fixes warnings like

   warning: Ignoring setting 'auto-allocate-uids' because experimental feature 'auto-allocate-uids' is not enabled
   warning: Ignoring setting 'impure-env' because experimental feature 'configurable-impure-env' is not enabled

when using the daemon and the user didn't actually set those settings.

Note: this also hides those settings from `nix config show`, but that
seems a good thing.
---
 src/libutil/config-impl.hh                |  2 +-
 src/libutil/config.cc                     |  4 +++-
 tests/functional/experimental-features.sh | 10 ++++++----
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/libutil/config-impl.hh b/src/libutil/config-impl.hh
index 9f69e8444..1da0cb638 100644
--- a/src/libutil/config-impl.hh
+++ b/src/libutil/config-impl.hh
@@ -4,7 +4,7 @@
  *
  * Template implementations (as opposed to mere declarations).
  *
- * This file is an exmample of the "impl.hh" pattern. See the
+ * This file is an example of the "impl.hh" pattern. See the
  * contributing guide.
  *
  * One only needs to include this when one is declaring a
diff --git a/src/libutil/config.cc b/src/libutil/config.cc
index 37f5b50c7..617c2ec89 100644
--- a/src/libutil/config.cc
+++ b/src/libutil/config.cc
@@ -84,7 +84,9 @@ void AbstractConfig::reapplyUnknownSettings()
 void Config::getSettings(std::map<std::string, SettingInfo> & res, bool overriddenOnly)
 {
     for (const auto & opt : _settings)
-        if (!opt.second.isAlias && (!overriddenOnly || opt.second.setting->overridden))
+        if (!opt.second.isAlias
+            && (!overriddenOnly || opt.second.setting->overridden)
+            && experimentalFeatureSettings.isEnabled(opt.second.setting->experimentalFeature))
             res.emplace(opt.first, SettingInfo{opt.second.setting->to_string(), opt.second.setting->description});
 }
 
diff --git a/tests/functional/experimental-features.sh b/tests/functional/experimental-features.sh
index 9ee4a53d4..12112b293 100644
--- a/tests/functional/experimental-features.sh
+++ b/tests/functional/experimental-features.sh
@@ -31,17 +31,19 @@ source common.sh
 NIX_CONFIG='
   experimental-features = nix-command
   accept-flake-config = true
-' nix config show accept-flake-config 1>$TEST_ROOT/stdout 2>$TEST_ROOT/stderr
-grepQuiet "false" $TEST_ROOT/stdout
+' expect 1 nix config show accept-flake-config 1>$TEST_ROOT/stdout 2>$TEST_ROOT/stderr
+[[ $(cat $TEST_ROOT/stdout) = '' ]]
 grepQuiet "Ignoring setting 'accept-flake-config' because experimental feature 'flakes' is not enabled" $TEST_ROOT/stderr
+grepQuiet "error: could not find setting 'accept-flake-config'" $TEST_ROOT/stderr
 
 # 'flakes' experimental-feature is disabled after, ignore and warn
 NIX_CONFIG='
   accept-flake-config = true
   experimental-features = nix-command
-' nix config show accept-flake-config 1>$TEST_ROOT/stdout 2>$TEST_ROOT/stderr
-grepQuiet "false" $TEST_ROOT/stdout
+' expect 1 nix config show accept-flake-config 1>$TEST_ROOT/stdout 2>$TEST_ROOT/stderr
+[[ $(cat $TEST_ROOT/stdout) = '' ]]
 grepQuiet "Ignoring setting 'accept-flake-config' because experimental feature 'flakes' is not enabled" $TEST_ROOT/stderr
+grepQuiet "error: could not find setting 'accept-flake-config'" $TEST_ROOT/stderr
 
 # 'flakes' experimental-feature is enabled before, process
 NIX_CONFIG='