Fix `nix build --dry-run` with CA derivations

Don’t try and assume that we know the output paths when we’ve just built
with `--dry-run`. Instead make `--dry-run` follow a different code path
that won’t assume the knowledge of the output paths at all.

Fix #6275

1 files changed, 26 insertions, 5 deletions

diff --git a/src/libstore/derived-path.cc b/src/libstore/derived-path.cc
index 194489580..0183bda35 100644
--- a/src/libstore/derived-path.cc
+++ b/src/libstore/derived-path.cc
@@ -11,6 +11,21 @@ nlohmann::json DerivedPath::Opaque::toJSON(ref<Store> store) const {
     return res;
 }
 
+nlohmann::json DerivedPath::Built::toJSON(ref<Store> store) const {
+    nlohmann::json res;
+    res["drvPath"] = store->printStorePath(drvPath);
+    // Fallback for the input-addressed derivation case: We expect to always be
+    // able to print the output paths, so let’s do it
+    auto knownOutputs = store->queryPartialDerivationOutputMap(drvPath);
+    for (const auto& output : outputs) {
+        if (knownOutputs.at(output))
+            res["outputs"][output] = store->printStorePath(knownOutputs.at(output).value());
+        else
+            res["outputs"][output] = nullptr;
+    }
+    return res;
+}
+
 nlohmann::json BuiltPath::Built::toJSON(ref<Store> store) const {
     nlohmann::json res;
     res["drvPath"] = store->printStorePath(drvPath);
@@ -35,16 +50,22 @@ StorePathSet BuiltPath::outPaths() const
     );
 }
 
-nlohmann::json derivedPathsWithHintsToJSON(const BuiltPaths & buildables, ref<Store> store) {
+template<typename T>
+nlohmann::json stuffToJSON(const std::vector<T> & ts, ref<Store> store) {
     auto res = nlohmann::json::array();
-    for (const BuiltPath & buildable : buildables) {
-        std::visit([&res, store](const auto & buildable) {
-            res.push_back(buildable.toJSON(store));
-        }, buildable.raw());
+    for (const T & t : ts) {
+        std::visit([&res, store](const auto & t) {
+            res.push_back(t.toJSON(store));
+        }, t.raw());
     }
     return res;
 }
 
+nlohmann::json derivedPathsWithHintsToJSON(const BuiltPaths & buildables, ref<Store> store)
+{ return stuffToJSON<BuiltPath>(buildables, store); }
+nlohmann::json derivedPathsToJSON(const DerivedPaths & paths, ref<Store> store)
+{ return stuffToJSON<DerivedPath>(paths, store); }
+
 
 std::string DerivedPath::Opaque::to_string(const Store & store) const {
     return store.printStorePath(path);