From caabc4f64889d5a4c47d6102b3aa1d3c80bbc107 Mon Sep 17 00:00:00 2001
From: John Ericson <John.Ericson@Obsidian.Systems>
Date: Wed, 12 Jul 2023 23:33:43 -0400
Subject: Feature gate `DownstreamPlaceholder::unknownCaOutput`

This is a part of CA derivations that we forgot to put behind the
experimental feature.

This was caught by @fricklerhandwerk in
https://github.com/NixOS/nix/pull/8369#discussion_r1258133719
---
 src/libstore/derivations.cc                  |  8 +++++---
 src/libstore/downstream-placeholder.cc       |  4 +++-
 src/libstore/downstream-placeholder.hh       |  5 ++++-
 src/libstore/tests/downstream-placeholder.cc | 16 ++++++++++++----
 4 files changed, 24 insertions(+), 9 deletions(-)

(limited to 'src/libstore')

diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index 6f63685d4..234d70ec5 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -878,9 +878,11 @@ std::optional<BasicDerivation> Derivation::tryResolve(
     for (auto & [inputDrv, inputOutputs] : inputDrvs) {
         for (auto & outputName : inputOutputs) {
             if (auto actualPath = get(inputDrvOutputs, { inputDrv, outputName })) {
-                inputRewrites.emplace(
-                    DownstreamPlaceholder::unknownCaOutput(inputDrv, outputName).render(),
-                    store.printStorePath(*actualPath));
+                if (experimentalFeatureSettings.isEnabled(Xp::CaDerivations)) {
+                    inputRewrites.emplace(
+                        DownstreamPlaceholder::unknownCaOutput(inputDrv, outputName).render(),
+                        store.printStorePath(*actualPath));
+                }
                 resolved.inputSrcs.insert(*actualPath);
             } else {
                 warn("output '%s' of input '%s' missing, aborting the resolving",
diff --git a/src/libstore/downstream-placeholder.cc b/src/libstore/downstream-placeholder.cc
index 1752738f2..d623c05e2 100644
--- a/src/libstore/downstream-placeholder.cc
+++ b/src/libstore/downstream-placeholder.cc
@@ -11,8 +11,10 @@ std::string DownstreamPlaceholder::render() const
 
 DownstreamPlaceholder DownstreamPlaceholder::unknownCaOutput(
     const StorePath & drvPath,
-    std::string_view outputName)
+    std::string_view outputName,
+    const ExperimentalFeatureSettings & xpSettings)
 {
+    xpSettings.require(Xp::CaDerivations);
     auto drvNameWithExtension = drvPath.name();
     auto drvName = drvNameWithExtension.substr(0, drvNameWithExtension.size() - 4);
     auto clearText = "nix-upstream-output:" + std::string { drvPath.hashPart() } + ":" + outputPathName(drvName, outputName);
diff --git a/src/libstore/downstream-placeholder.hh b/src/libstore/downstream-placeholder.hh
index f0c0dee77..97f77e6b8 100644
--- a/src/libstore/downstream-placeholder.hh
+++ b/src/libstore/downstream-placeholder.hh
@@ -52,10 +52,13 @@ public:
      *
      * The derivation itself is known (we have a store path for it), but
      * the output doesn't yet have a known store path.
+     *
+     * @param xpSettings Stop-gap to avoid globals during unit tests.
      */
     static DownstreamPlaceholder unknownCaOutput(
         const StorePath & drvPath,
-        std::string_view outputName);
+        std::string_view outputName,
+        const ExperimentalFeatureSettings & xpSettings = experimentalFeatureSettings);
 
     /**
      * Create a placehold for the output of an unknown derivation.
diff --git a/src/libstore/tests/downstream-placeholder.cc b/src/libstore/tests/downstream-placeholder.cc
index ec3e1000f..fd29530ac 100644
--- a/src/libstore/tests/downstream-placeholder.cc
+++ b/src/libstore/tests/downstream-placeholder.cc
@@ -5,17 +5,24 @@
 namespace nix {
 
 TEST(DownstreamPlaceholder, unknownCaOutput) {
+    /**
+     * We set these in tests rather than the regular globals so we don't have
+     * to worry about race conditions if the tests run concurrently.
+     */
+    ExperimentalFeatureSettings mockXpSettings;
+    mockXpSettings.set("experimental-features", "ca-derivations");
+
     ASSERT_EQ(
         DownstreamPlaceholder::unknownCaOutput(
             StorePath { "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv" },
-            "out").render(),
+            "out",
+            mockXpSettings).render(),
         "/0c6rn30q4frawknapgwq386zq358m8r6msvywcvc89n6m5p2dgbz");
 }
 
 TEST(DownstreamPlaceholder, unknownDerivation) {
     /**
-     * We set these in tests rather than the regular globals so we don't have
-     * to worry about race conditions if the tests run concurrently.
+     * Same reason as above
      */
     ExperimentalFeatureSettings mockXpSettings;
     mockXpSettings.set("experimental-features", "dynamic-derivations ca-derivations");
@@ -24,7 +31,8 @@ TEST(DownstreamPlaceholder, unknownDerivation) {
         DownstreamPlaceholder::unknownDerivation(
             DownstreamPlaceholder::unknownCaOutput(
                 StorePath { "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv.drv" },
-                "out"),
+                "out",
+                mockXpSettings),
             "out",
             mockXpSettings).render(),
         "/0gn6agqxjyyalf0dpihgyf49xq5hqxgw100f0wydnj6yqrhqsb3w");
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