From 6951b26ed0a806c03ad73069ccc925ef6ac158e6 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Fri, 1 Apr 2022 03:57:51 +0000
Subject: [PATCH] Require (new) computed-derivations experimental feature for !
 installable

---
 src/libcmd/installables.cc           | 1 +
 src/libutil/experimental-features.cc | 1 +
 src/libutil/experimental-features.hh | 1 +
 tests/build-explicit-output.sh       | 3 +++
 4 files changed, 6 insertions(+)

diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 1d44ffe84..ab13f11df 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -740,6 +740,7 @@ std::vector<std::shared_ptr<Installable>> SourceExprCommand::parseInstallables(
                     result.push_back(std::make_shared<InstallableIndexedStorePath>(
                         store,
                         DerivedPath::Built::parse(*store, s)));
+                    settings.requireExperimentalFeature(Xp::ComputedDerivations);
                     continue;
                 } catch (BadStorePath &) {
                 } catch (...) {
diff --git a/src/libutil/experimental-features.cc b/src/libutil/experimental-features.cc
index e033a4116..c1e574c0d 100644
--- a/src/libutil/experimental-features.cc
+++ b/src/libutil/experimental-features.cc
@@ -13,6 +13,7 @@ std::map<ExperimentalFeature, std::string> stringifiedXpFeatures = {
     { Xp::RecursiveNix, "recursive-nix" },
     { Xp::NoUrlLiterals, "no-url-literals" },
     { Xp::FetchClosure, "fetch-closure" },
+    { Xp::ComputedDerivations, "computed-derivations" },
 };
 
 const std::optional<ExperimentalFeature> parseExperimentalFeature(const std::string_view & name)
diff --git a/src/libutil/experimental-features.hh b/src/libutil/experimental-features.hh
index 3a254b423..58e082c72 100644
--- a/src/libutil/experimental-features.hh
+++ b/src/libutil/experimental-features.hh
@@ -22,6 +22,7 @@ enum struct ExperimentalFeature
     RecursiveNix,
     NoUrlLiterals,
     FetchClosure,
+    ComputedDerivations, // RFC 92
 };
 
 /**
diff --git a/tests/build-explicit-output.sh b/tests/build-explicit-output.sh
index fcb263913..0f2f428db 100644
--- a/tests/build-explicit-output.sh
+++ b/tests/build-explicit-output.sh
@@ -1,5 +1,8 @@
 source common.sh
 
+enableFeatures "computed-derivations"
+restartDaemon
+
 drv=$(nix eval -f multiple-outputs.nix --raw a.drvPath)
 if nix build "$drv!not-an-output" --json; then
     fail "'not-an-output' should fail to build"