Remove references from fixed output derivation ab syntax

In other words, use a plain `ContentAddress` not
`ContentAddressWithReferences` for `DerivationOutput::CAFixed`.

Supporting fixed output derivations with (fixed) references would be a
cool feature, but it is out of scope at this moment.

src/libexpr/primops.cc

@@ -1303,11 +1303,9 @@ drvName, Bindings * attrs, Value & v)
         auto method = ingestionMethod.value_or(FileIngestionMethod::Flat);
 
         DerivationOutput::CAFixed dof {
-            .ca = ContentAddressWithReferences::fromParts(
+            .ca = ContentAddress::fromParts(
                 std::move(method),
-                std::move(h),
+                std::move(h)),
-                // FIXME non-trivial fixed refs set
-                {}),
         };
 
         drv.env["out"] = state.store->printStorePath(dof.path(*state.store, drvName, "out"));

src/libstore/build/derivation-goal.cc

@@ -274,11 +274,13 @@ void DerivationGoal::haveDerivation()
                         )
                     )
                 );
-            else
+            else {
+                auto * cap = getDerivationCA(*drv);
                 addWaitee(upcast_goal(worker.makePathSubstitutionGoal(
                     status.known->path,
                     buildMode == bmRepair ? Repair : NoRepair,
-                    getDerivationCA(*drv))));
+                    cap ? std::optional { *cap } : std::nullopt)));
+            }
         }
 
     if (waitees.empty()) /* to prevent hang (no wake-up event) */

src/libstore/content-address.cc

@@ -196,6 +196,11 @@ const Hash & ContentAddress::getHash() const
     }, raw);
 }
 
+std::string ContentAddress::printMethodAlgo() const {
+    return getMethod().renderPrefix()
+        + printHashType(getHash().type);
+}
+
 bool StoreReferences::empty() const
 {
     return !self && others.empty();
@@ -271,9 +276,4 @@ Hash ContentAddressWithReferences::getHash() const
     }, raw);
 }
 
-std::string ContentAddressWithReferences::printMethodAlgo() const {
-    return getMethod().renderPrefix()
-        + printHashType(getHash().type);
-}
-
 }

src/libstore/content-address.hh

@@ -177,6 +177,8 @@ struct ContentAddress
     ContentAddressMethod getMethod() const;
 
     const Hash & getHash() const;
+
+    std::string printMethodAlgo() const;
 };
 
 std::string renderContentAddress(std::optional<ContentAddress> ca);
@@ -286,8 +288,6 @@ struct ContentAddressWithReferences
     ContentAddressMethod getMethod() const;
 
     Hash getHash() const;
-
-    std::string printMethodAlgo() const;
 };
 
 }

src/libstore/derivations.cc

@@ -38,7 +38,7 @@ StorePath DerivationOutput::CAFixed::path(const Store & store, std::string_view
 {
     return store.makeFixedOutputPathFromCA(
         outputPathName(drvName, outputName),
-        ca);
+        ContentAddressWithReferences::withoutRefs(ca));
 }
 
 
@@ -230,11 +230,9 @@ static DerivationOutput parseDerivationOutput(const Store & store,
             validatePath(pathS);
             auto hash = Hash::parseNonSRIUnprefixed(hashS, hashType);
             return DerivationOutput::CAFixed {
-                .ca = ContentAddressWithReferences::fromParts(
+                .ca = ContentAddress::fromParts(
                     std::move(method),
-                    std::move(hash),
+                    std::move(hash)),
-                    // FIXME non-trivial fixed refs set
-                    {}),
             };
         } else {
             experimentalFeatureSettings.require(Xp::CaDerivations);
@@ -1020,10 +1018,9 @@ DerivationOutput DerivationOutput::fromJSON(
     else if (keys == (std::set<std::string_view> { "path", "hashAlgo", "hash" })) {
         auto [method, hashType] = methodAlgo();
         auto dof = DerivationOutput::CAFixed {
-            .ca = ContentAddressWithReferences::fromParts(
+            .ca = ContentAddress::fromParts(
                 std::move(method),
-                Hash::parseNonSRIUnprefixed((std::string) json["hash"], hashType),
+                Hash::parseNonSRIUnprefixed((std::string) json["hash"], hashType)),
-                {}),
         };
         if (dof.path(store, drvName, outputName) != store.parseStorePath((std::string) json["path"]))
             throw Error("Path doesn't match derivation output");

src/libstore/derivations.hh

@@ -36,9 +36,11 @@ struct DerivationOutputInputAddressed
 struct DerivationOutputCAFixed
 {
     /**
-     * hash and refs used for expected hash computation
+     * Method and hash used for expected hash computation.
+     *
+     * References are not allowed by fiat.
      */
-    ContentAddressWithReferences ca; /* hash and refs used for validating output */
+    ContentAddress ca;
 
     /**
      * Return the \ref StorePath "store path" corresponding to this output

src/libstore/misc.cc

@@ -83,26 +83,16 @@ void Store::computeFSClosure(const StorePath & startPath,
 }
 
 
-std::optional<ContentAddress> getDerivationCA(const BasicDerivation & drv)
+const ContentAddress * getDerivationCA(const BasicDerivation & drv)
 {
     auto out = drv.outputs.find("out");
     if (out == drv.outputs.end())
-        return std::nullopt;
+        return nullptr;
     if (auto dof = std::get_if<DerivationOutput::CAFixed>(&out->second)) {
-        return std::visit(overloaded {
+
-            [&](const TextInfo & ti) -> std::optional<ContentAddress> {
+        return &dof->ca;
-                if (!ti.references.empty())
-                    return std::nullopt;
-                return ti.hash;
-            },
-            [&](const FixedOutputInfo & fi) -> std::optional<ContentAddress> {
-                if (!fi.references.empty())
-                    return std::nullopt;
-                return fi.hash;
-            },
-        }, dof->ca.raw);
     }
-    return std::nullopt;
+    return nullptr;
 }
 
 void Store::queryMissing(const std::vector<DerivedPath> & targets,
@@ -152,7 +142,13 @@ void Store::queryMissing(const std::vector<DerivedPath> & targets,
         if (drvState_->lock()->done) return;
 
         SubstitutablePathInfos infos;
-        querySubstitutablePathInfos({{outPath, getDerivationCA(*drv)}}, infos);
+        auto * cap = getDerivationCA(*drv);
+        querySubstitutablePathInfos({
+            {
+                outPath,
+                cap ? std::optional { *cap } : std::nullopt,
+            },
+        }, infos);
 
         if (infos.empty()) {
             drvState_->lock()->done = true;

src/libstore/store-api.hh

@@ -1022,7 +1022,7 @@ std::optional<ValidPathInfo> decodeValidPathInfo(
  */
 std::pair<std::string, Store::Params> splitUriAndParams(const std::string & uri);
 
-std::optional<ContentAddress> getDerivationCA(const BasicDerivation & drv);
+const ContentAddress * getDerivationCA(const BasicDerivation & drv);
 
 std::map<DrvOutput, StorePath> drvOutputReferences(
     Store & store,

src/libstore/tests/derivation.cc

@@ -74,20 +74,31 @@ TEST_JSON(DerivationTest, inputAddressed,
     }),
     "drv-name", "output-name")
 
-TEST_JSON(DerivationTest, caFixed,
+TEST_JSON(DerivationTest, caFixedFlat,
+    R"({
+        "hashAlgo": "sha256",
+        "hash": "894517c9163c896ec31a2adbd33c0681fd5f45b2c0ef08a64c92a03fb97f390f",
+        "path": "/nix/store/rhcg9h16sqvlbpsa6dqm57sbr2al6nzg-drv-name-output-name"
+    })",
+    (DerivationOutput::CAFixed {
+        .ca = FixedOutputHash {
+            .method = FileIngestionMethod::Flat,
+            .hash = Hash::parseAnyPrefixed("sha256-iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="),
+        },
+    }),
+    "drv-name", "output-name")
+
+TEST_JSON(DerivationTest, caFixedNAR,
     R"({
         "hashAlgo": "r:sha256",
         "hash": "894517c9163c896ec31a2adbd33c0681fd5f45b2c0ef08a64c92a03fb97f390f",
         "path": "/nix/store/c015dhfh5l0lp6wxyvdn7bmwhbbr6hr9-drv-name-output-name"
     })",
     (DerivationOutput::CAFixed {
-        .ca = FixedOutputInfo {
+        .ca = FixedOutputHash {
-            .hash = {
             .method = FileIngestionMethod::Recursive,
             .hash = Hash::parseAnyPrefixed("sha256-iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="),
         },
-            .references = {},
-        },
     }),
     "drv-name", "output-name")
 
@@ -98,12 +109,9 @@ TEST_JSON(DynDerivationTest, caFixedText,
         "path": "/nix/store/6s1zwabh956jvhv4w9xcdb5jiyanyxg1-drv-name-output-name"
     })",
     (DerivationOutput::CAFixed {
-        .ca = TextInfo {
+        .ca = TextHash {
-            .hash = {
             .hash = Hash::parseAnyPrefixed("sha256-iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="),
         },
-            .references = {},
-        },
     }),
     "drv-name", "output-name")