Simplify ContentAddress

Whereas `ContentAddressWithReferences` is a sum type complex because different
varieties support different notions of reference, and
`ContentAddressMethod` is a nested enum to support that,
`ContentAddress` can be a simple pair of a method and hash.

`ContentAddress` does not need to be a sum type on the outside because
the choice of method doesn't effect what type of hashes we can use.

Co-Authored-By: Cale Gibbard <cgibbard@gmail.com>

perl/lib/Nix/Store.xs

@@ -294,10 +294,8 @@ SV * makeFixedOutputPath(int recursive, char * algo, char * hash, char * name)
             auto h = Hash::parseAny(hash, parseHashType(algo));
             auto method = recursive ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat;
             auto path = store()->makeFixedOutputPath(name, FixedOutputInfo {
-                .hash = {
+                .method = method,
-                    .method = method,
+                .hash = h,
-                    .hash = h,
-                },
                 .references = {},
             });
             XPUSHs(sv_2mortal(newSVpv(store()->printStorePath(path).c_str(), 0)));

src/libexpr/primops.cc

@@ -1300,9 +1300,10 @@ drvName, Bindings * attrs, Value & v)
         auto method = ingestionMethod.value_or(FileIngestionMethod::Flat);
 
         DerivationOutput::CAFixed dof {
-            .ca = ContentAddress::fromParts(
+            .ca = ContentAddress {
-                std::move(method),
+                .method = std::move(method),
-                std::move(h)),
+                .hash = std::move(h),
+            },
         };
 
         drv.env["out"] = state.store->printStorePath(dof.path(*state.store, drvName, "out"));
@@ -2162,10 +2163,8 @@ static void addPath(
         std::optional<StorePath> expectedStorePath;
         if (expectedHash)
             expectedStorePath = state.store->makeFixedOutputPath(name, FixedOutputInfo {
-                .hash = {
+                .method = method,
-                    .method = method,
+                .hash = *expectedHash,
-                    .hash = *expectedHash,
-                },
                 .references = {},
             });
 

src/libexpr/primops/fetchTree.cc

@@ -254,10 +254,8 @@ static void fetch(EvalState & state, const PosIdx pos, Value * * args, Value & v
         auto expectedPath = state.store->makeFixedOutputPath(
             name,
             FixedOutputInfo {
-                .hash = {
+                .method = unpack ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat,
-                    .method = unpack ? FileIngestionMethod::Recursive : FileIngestionMethod::Flat,
+                .hash = *expectedHash,
-                    .hash = *expectedHash,
-                },
                 .references = {}
             });
 

src/libfetchers/fetchers.cc

@@ -217,10 +217,8 @@ StorePath Input::computeStorePath(Store & store) const
     if (!narHash)
         throw Error("cannot compute store path for unlocked input '%s'", to_string());
     return store.makeFixedOutputPath(getName(), FixedOutputInfo {
-        .hash = {
+        .method = FileIngestionMethod::Recursive,
-            .method = FileIngestionMethod::Recursive,
+        .hash = *narHash,
-            .hash = *narHash,
-        },
         .references = {},
     });
 }

src/libfetchers/tarball.cc

@@ -77,10 +77,8 @@ DownloadFileResult downloadFile(
             *store,
             name,
             FixedOutputInfo {
-                .hash = {
+                .method = FileIngestionMethod::Flat,
-                    .method = FileIngestionMethod::Flat,
+                .hash = hash,
-                    .hash = hash,
-                },
                 .references = {},
             },
             hashString(htSHA256, sink.s),

src/libstore/binary-cache-store.cc

@@ -309,10 +309,8 @@ StorePath BinaryCacheStore::addToStoreFromDump(Source & dump, std::string_view n
             *this,
             name,
             FixedOutputInfo {
-                .hash = {
+                .method = method,
-                    .method = method,
+                .hash = nar.first,
-                    .hash = nar.first,
-                },
                 .references = {
                     .others = references,
                     // caller is not capable of creating a self-reference, because this is content-addressed without modulus
@@ -428,10 +426,8 @@ StorePath BinaryCacheStore::addToStore(
             *this,
             name,
             FixedOutputInfo {
-                .hash = {
+                .method = method,
-                    .method = method,
+                .hash = h,
-                    .hash = h,
-                },
                 .references = {
                     .others = references,
                     // caller is not capable of creating a self-reference, because this is content-addressed without modulus
@@ -465,8 +461,8 @@ StorePath BinaryCacheStore::addTextToStore(
             *this,
             std::string { name },
             TextInfo {
-                { .hash = textHash },
+                .hash = textHash,
-                references,
+                .references = references,
             },
             nar.first,
         };

src/libstore/build/local-derivation-goal.cc

@@ -2538,16 +2538,16 @@ SingleDrvOutputs LocalDerivationGoal::registerOutputs()
             },
 
             [&](const DerivationOutput::CAFixed & dof) {
-                auto wanted = dof.ca.getHash();
+                auto & wanted = dof.ca.hash;
 
                 auto newInfo0 = newInfoFromCA(DerivationOutput::CAFloating {
-                    .method = dof.ca.getMethod(),
+                    .method = dof.ca.method,
                     .hashType = wanted.type,
                 });
 
                 /* Check wanted hash */
                 assert(newInfo0.ca);
-                auto got = newInfo0.ca->getHash();
+                auto & got = newInfo0.ca->hash;
                 if (wanted != got) {
                     /* Throw an error after registering the path as
                        valid. */

src/libstore/content-address.cc

@@ -4,11 +4,6 @@
 
 namespace nix {
 
-std::string FixedOutputHash::printMethodAlgo() const
-{
-    return makeFileIngestionPrefix(method) + printHashType(hash.type);
-}
-
 std::string makeFileIngestionPrefix(FileIngestionMethod m)
 {
     switch (m) {
@@ -42,21 +37,6 @@ ContentAddressMethod ContentAddressMethod::parsePrefix(std::string_view & m)
     return method;
 }
 
-std::string ContentAddress::render() const
-{
-    return std::visit(overloaded {
-        [](const TextHash & th) {
-            return "text:"
-                + th.hash.to_string(Base32, true);
-        },
-        [](const FixedOutputHash & fsh) {
-            return "fixed:"
-                + makeFileIngestionPrefix(fsh.method)
-                + fsh.hash.to_string(Base32, true);
-        }
-    }, raw);
-}
-
 std::string ContentAddressMethod::render(HashType ht) const
 {
     return std::visit(overloaded {
@@ -69,6 +49,20 @@ std::string ContentAddressMethod::render(HashType ht) const
     }, raw);
 }
 
+std::string ContentAddress::render() const
+{
+    return std::visit(overloaded {
+        [](const TextIngestionMethod &) -> std::string {
+            return "text:";
+        },
+        [](const FileIngestionMethod & method) {
+            return "fixed:"
+                + makeFileIngestionPrefix(method);
+        },
+    }, method.raw)
+        + this->hash.to_string(Base32, true);
+}
+
 /**
  * Parses content address strings up to the hash.
  */
@@ -118,22 +112,12 @@ ContentAddress ContentAddress::parse(std::string_view rawCa)
 {
     auto rest = rawCa;
 
-    auto [caMethod, hashType_] = parseContentAddressMethodPrefix(rest);
+    auto [caMethod, hashType] = parseContentAddressMethodPrefix(rest);
-    auto hashType = hashType_; // work around clang bug
 
-    return std::visit(overloaded {
+    return ContentAddress {
-        [&](TextIngestionMethod &) {
+        .method = std::move(caMethod).raw,
-            return ContentAddress(TextHash {
+        .hash = Hash::parseNonSRIUnprefixed(rest, hashType),
-                .hash = Hash::parseNonSRIUnprefixed(rest, hashType)
+    };
-            });
-        },
-        [&](FileIngestionMethod & fim) {
-            return ContentAddress(FixedOutputHash {
-                .method = fim,
-                .hash = Hash::parseNonSRIUnprefixed(rest, hashType),
-            });
-        },
-    }, caMethod.raw);
 }
 
 std::pair<ContentAddressMethod, HashType> ContentAddressMethod::parse(std::string_view caMethod)
@@ -156,52 +140,10 @@ std::string renderContentAddress(std::optional<ContentAddress> ca)
     return ca ? ca->render() : "";
 }
 
-ContentAddress ContentAddress::fromParts(
-    ContentAddressMethod method, Hash hash) noexcept
-{
-    return std::visit(overloaded {
-        [&](TextIngestionMethod _) -> ContentAddress {
-            return TextHash {
-                .hash = std::move(hash),
-            };
-        },
-        [&](FileIngestionMethod m2) -> ContentAddress {
-            return FixedOutputHash {
-                .method = std::move(m2),
-                .hash = std::move(hash),
-            };
-        },
-    }, method.raw);
-}
-
-ContentAddressMethod ContentAddress::getMethod() const
-{
-    return std::visit(overloaded {
-        [](const TextHash & th) -> ContentAddressMethod {
-            return TextIngestionMethod {};
-        },
-        [](const FixedOutputHash & fsh) -> ContentAddressMethod {
-            return fsh.method;
-        },
-    }, raw);
-}
-
-const Hash & ContentAddress::getHash() const
-{
-    return std::visit(overloaded {
-        [](const TextHash & th) -> auto & {
-            return th.hash;
-        },
-        [](const FixedOutputHash & fsh) -> auto & {
-            return fsh.hash;
-        },
-    }, raw);
-}
-
 std::string ContentAddress::printMethodAlgo() const
 {
-    return getMethod().renderPrefix()
+    return method.renderPrefix()
-        + printHashType(getHash().type);
+        + printHashType(hash.type);
 }
 
 bool StoreReferences::empty() const
@@ -217,19 +159,20 @@ size_t StoreReferences::size() const
 ContentAddressWithReferences ContentAddressWithReferences::withoutRefs(const ContentAddress & ca) noexcept
 {
     return std::visit(overloaded {
-        [&](const TextHash & h) -> ContentAddressWithReferences {
+        [&](const TextIngestionMethod &) -> ContentAddressWithReferences {
             return TextInfo {
-                .hash = h,
+                .hash = ca.hash,
                 .references = {},
             };
         },
-        [&](const FixedOutputHash & h) -> ContentAddressWithReferences {
+        [&](const FileIngestionMethod & method) -> ContentAddressWithReferences {
             return FixedOutputInfo {
-                .hash = h,
+                .method = method,
+                .hash = ca.hash,
                 .references = {},
             };
         },
-    }, ca.raw);
+    }, ca.method.raw);
 }
 
 std::optional<ContentAddressWithReferences> ContentAddressWithReferences::fromPartsOpt(
@@ -241,7 +184,7 @@ std::optional<ContentAddressWithReferences> ContentAddressWithReferences::fromPa
                 return std::nullopt;
             return ContentAddressWithReferences {
                 TextInfo {
-                    .hash = { .hash = std::move(hash) },
+                    .hash = std::move(hash),
                     .references = std::move(refs.others),
                 }
             };
@@ -249,10 +192,8 @@ std::optional<ContentAddressWithReferences> ContentAddressWithReferences::fromPa
         [&](FileIngestionMethod m2) -> std::optional<ContentAddressWithReferences> {
             return ContentAddressWithReferences {
                 FixedOutputInfo {
-                    .hash = {
+                    .method = m2,
-                        .method = m2,
+                    .hash = std::move(hash),
-                        .hash = std::move(hash),
-                    },
                     .references = std::move(refs),
                 }
             };
@@ -267,7 +208,7 @@ ContentAddressMethod ContentAddressWithReferences::getMethod() const
             return TextIngestionMethod {};
         },
         [](const FixedOutputInfo & fsh) -> ContentAddressMethod {
-            return fsh.hash.method;
+            return fsh.method;
         },
     }, raw);
 }
@@ -276,10 +217,10 @@ Hash ContentAddressWithReferences::getHash() const
 {
     return std::visit(overloaded {
         [](const TextInfo & th) {
-            return th.hash.hash;
+            return th.hash;
         },
         [](const FixedOutputInfo & fsh) {
-            return fsh.hash.hash;
+            return fsh.hash;
         },
     }, raw);
 }

src/libstore/content-address.hh

@@ -113,37 +113,6 @@ struct ContentAddressMethod
  * Mini content address
  */
 
-/**
- * Somewhat obscure, used by \ref Derivation derivations and
- * `builtins.toFile` currently.
- */
-struct TextHash {
-    /**
-     * Hash of the contents of the text/file.
-     */
-    Hash hash;
-
-    GENERATE_CMP(TextHash, me->hash);
-};
-
-/**
- * Used by most store objects that are content-addressed.
- */
-struct FixedOutputHash {
-    /**
-     * How the file system objects are serialized
-     */
-    FileIngestionMethod method;
-    /**
-     * Hash of that serialization
-     */
-    Hash hash;
-
-    std::string printMethodAlgo() const;
-
-    GENERATE_CMP(FixedOutputHash, me->method, me->hash);
-};
-
 /**
  * We've accumulated several types of content-addressed paths over the
  * years; fixed-output derivations support multiple hash algorithms and
@@ -158,19 +127,17 @@ struct FixedOutputHash {
  */
 struct ContentAddress
 {
-    typedef std::variant<
+    /**
-        TextHash,
+     * How the file system objects are serialized
-        FixedOutputHash
+     */
-    > Raw;
+    ContentAddressMethod method;
 
-    Raw raw;
+    /**
+     * Hash of that serialization
+     */
+    Hash hash;
 
-    GENERATE_CMP(ContentAddress, me->raw);
+    GENERATE_CMP(ContentAddress, me->method, me->hash);
-
-    /* The moral equivalent of `using Raw::Raw;` */
-    ContentAddress(auto &&... arg)
-        : raw(std::forward<decltype(arg)>(arg)...)
-    { }
 
     /**
      * Compute the content-addressability assertion
@@ -183,20 +150,6 @@ struct ContentAddress
 
     static std::optional<ContentAddress> parseOpt(std::string_view rawCaOpt);
 
-    /**
-     * Create a `ContentAddress` from 2 parts:
-     *
-     * @param method Way ingesting the file system data.
-     *
-     * @param hash Hash of ingested file system data.
-     */
-    static ContentAddress fromParts(
-        ContentAddressMethod method, Hash hash) noexcept;
-
-    ContentAddressMethod getMethod() const;
-
-    const Hash & getHash() const;
-
     std::string printMethodAlgo() const;
 };
 
@@ -219,7 +172,8 @@ std::string renderContentAddress(std::optional<ContentAddress> ca);
  * References to other store objects are tracked with store paths, self
  * references however are tracked with a boolean.
  */
-struct StoreReferences {
+struct StoreReferences
+{
     /**
      * References to other store objects
      */
@@ -246,8 +200,13 @@ struct StoreReferences {
 };
 
 // This matches the additional info that we need for makeTextPath
-struct TextInfo {
+struct TextInfo
-    TextHash hash;
+{
+    /**
+     * Hash of the contents of the text/file.
+     */
+    Hash hash;
+
     /**
      * References to other store objects only; self references
      * disallowed
@@ -257,8 +216,18 @@ struct TextInfo {
     GENERATE_CMP(TextInfo, me->hash, me->references);
 };
 
-struct FixedOutputInfo {
+struct FixedOutputInfo
-    FixedOutputHash hash;
+{
+    /**
+     * How the file system objects are serialized
+     */
+    FileIngestionMethod method;
+
+    /**
+     * Hash of that serialization
+     */
+    Hash hash;
+
     /**
      * References to other store objects or this one.
      */

src/libstore/derivations.cc

@@ -232,9 +232,10 @@ static DerivationOutput parseDerivationOutput(const Store & store,
             validatePath(pathS);
             auto hash = Hash::parseNonSRIUnprefixed(hashS, hashType);
             return DerivationOutput::CAFixed {
-                .ca = ContentAddress::fromParts(
+                .ca = ContentAddress {
-                    std::move(method),
+                    .method = std::move(method),
-                    std::move(hash)),
+                    .hash = std::move(hash),
+                },
             };
         } else {
             experimentalFeatureSettings.require(Xp::CaDerivations);
@@ -395,7 +396,7 @@ std::string Derivation::unparse(const Store & store, bool maskOutputs,
             [&](const DerivationOutput::CAFixed & dof) {
                 s += ','; printUnquotedString(s, maskOutputs ? "" : store.printStorePath(dof.path(store, name, i.first)));
                 s += ','; printUnquotedString(s, dof.ca.printMethodAlgo());
-                s += ','; printUnquotedString(s, dof.ca.getHash().to_string(Base16, false));
+                s += ','; printUnquotedString(s, dof.ca.hash.to_string(Base16, false));
             },
             [&](const DerivationOutput::CAFloating & dof) {
                 s += ','; printUnquotedString(s, "");
@@ -628,7 +629,7 @@ DrvHash hashDerivationModulo(Store & store, const Derivation & drv, bool maskOut
             auto & dof = std::get<DerivationOutput::CAFixed>(i.second.raw());
             auto hash = hashString(htSHA256, "fixed:out:"
                 + dof.ca.printMethodAlgo() + ":"
-                + dof.ca.getHash().to_string(Base16, false) + ":"
+                + dof.ca.hash.to_string(Base16, false) + ":"
                 + store.printStorePath(dof.path(store, drv.name, i.first)));
             outputHashes.insert_or_assign(i.first, std::move(hash));
         }
@@ -780,7 +781,7 @@ void writeDerivation(Sink & out, const Store & store, const BasicDerivation & dr
             [&](const DerivationOutput::CAFixed & dof) {
                 out << store.printStorePath(dof.path(store, drv.name, i.first))
                     << dof.ca.printMethodAlgo()
-                    << dof.ca.getHash().to_string(Base16, false);
+                    << dof.ca.hash.to_string(Base16, false);
             },
             [&](const DerivationOutput::CAFloating & dof) {
                 out << ""
@@ -970,7 +971,7 @@ nlohmann::json DerivationOutput::toJSON(
         [&](const DerivationOutput::CAFixed & dof) {
             res["path"] = store.printStorePath(dof.path(store, drvName, outputName));
             res["hashAlgo"] = dof.ca.printMethodAlgo();
-            res["hash"] = dof.ca.getHash().to_string(Base16, false);
+            res["hash"] = dof.ca.hash.to_string(Base16, false);
             // FIXME print refs?
         },
         [&](const DerivationOutput::CAFloating & dof) {
@@ -1017,9 +1018,10 @@ DerivationOutput DerivationOutput::fromJSON(
     else if (keys == (std::set<std::string_view> { "path", "hashAlgo", "hash" })) {
         auto [method, hashType] = methodAlgo();
         auto dof = DerivationOutput::CAFixed {
-            .ca = ContentAddress::fromParts(
+            .ca = ContentAddress {
-                std::move(method),
+                .method = std::move(method),
-                Hash::parseNonSRIUnprefixed((std::string) json["hash"], hashType)),
+                .hash = 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/local-store.cc

@@ -1249,27 +1249,17 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
                     printStorePath(info.path), info.narSize, hashResult.second);
 
             if (info.ca) {
-                if (auto foHash = std::get_if<FixedOutputHash>(&info.ca->raw)) {
+                auto & specified = *info.ca;
-                    auto actualFoHash = hashCAPath(
+                auto actualHash = hashCAPath(
-                        foHash->method,
+                    specified.method,
-                        foHash->hash.type,
+                    specified.hash.type,
-                        info.path
+                    info.path
-                    );
+                );
-                    if (foHash->hash != actualFoHash.hash) {
+                if (specified.hash != actualHash.hash) {
-                        throw Error("ca hash mismatch importing path '%s';\n  specified: %s\n  got:       %s",
+                    throw Error("ca hash mismatch importing path '%s';\n  specified: %s\n  got:       %s",
-                            printStorePath(info.path),
+                        printStorePath(info.path),
-                            foHash->hash.to_string(Base32, true),
+                        specified.hash.to_string(Base32, true),
-                            actualFoHash.hash.to_string(Base32, true));
+                        actualHash.hash.to_string(Base32, true));
-                    }
-                }
-                if (auto textHash = std::get_if<TextHash>(&info.ca->raw)) {
-                    auto actualTextHash = hashString(htSHA256, readFile(realPath));
-                    if (textHash->hash != actualTextHash) {
-                        throw Error("ca hash mismatch importing path '%s';\n  specified: %s\n  got:       %s",
-                            printStorePath(info.path),
-                            textHash->hash.to_string(Base32, true),
-                            actualTextHash.to_string(Base32, true));
-                    }
                 }
             }
 
@@ -1349,10 +1339,8 @@ StorePath LocalStore::addToStoreFromDump(Source & source0, std::string_view name
     auto [hash, size] = hashSink->finish();
 
     ContentAddressWithReferences desc = FixedOutputInfo {
-        .hash = {
+        .method = method,
-            .method = method,
+        .hash = hash,
-            .hash = hash,
-        },
         .references = {
             .others = references,
             // caller is not capable of creating a self-reference, because this is content-addressed without modulus
@@ -1428,8 +1416,8 @@ StorePath LocalStore::addTextToStore(
 {
     auto hash = hashString(htSHA256, s);
     auto dstPath = makeTextPath(name, TextInfo {
-        { .hash = hash },
+        .hash = hash,
-        references,
+        .references = references,
     });
 
     addTempRoot(dstPath);
@@ -1459,7 +1447,10 @@ StorePath LocalStore::addTextToStore(
             ValidPathInfo info { dstPath, narHash };
             info.narSize = sink.s.size();
             info.references = references;
-            info.ca = TextHash { .hash = hash };
+            info.ca = {
+                .method = TextIngestionMethod {},
+                .hash = hash,
+            };
             registerValidPath(info);
         }
 
@@ -1856,33 +1847,39 @@ void LocalStore::queryRealisationUncached(const DrvOutput & id,
     }
 }
 
-FixedOutputHash LocalStore::hashCAPath(
+ContentAddress LocalStore::hashCAPath(
-    const FileIngestionMethod & method, const HashType & hashType,
+    const ContentAddressMethod & method, const HashType & hashType,
     const StorePath & path)
 {
     return hashCAPath(method, hashType, Store::toRealPath(path), path.hashPart());
 }
 
-FixedOutputHash LocalStore::hashCAPath(
+ContentAddress LocalStore::hashCAPath(
-    const FileIngestionMethod & method,
+    const ContentAddressMethod & method,
     const HashType & hashType,
     const Path & path,
     const std::string_view pathHash
 )
 {
     HashModuloSink caSink ( hashType, std::string(pathHash) );
-    switch (method) {
+    std::visit(overloaded {
-    case FileIngestionMethod::Recursive:
+        [&](const TextIngestionMethod &) {
-        dumpPath(path, caSink);
+            readFile(path, caSink);
-        break;
+        },
-    case FileIngestionMethod::Flat:
+        [&](const FileIngestionMethod & m2) {
-        readFile(path, caSink);
+            switch (m2) {
-        break;
+            case FileIngestionMethod::Recursive:
-    }
+                dumpPath(path, caSink);
-    auto hash = caSink.finish().first;
+                break;
-    return FixedOutputHash{
+            case FileIngestionMethod::Flat:
+                readFile(path, caSink);
+                break;
+            }
+        },
+    }, method.raw);
+    return ContentAddress {
         .method = method,
-        .hash = hash,
+        .hash = caSink.finish().first,
     };
 }
 

src/libstore/local-store.hh

@@ -345,13 +345,13 @@ private:
     void signRealisation(Realisation &);
 
     // XXX: Make a generic `Store` method
-    FixedOutputHash hashCAPath(
+    ContentAddress hashCAPath(
-        const FileIngestionMethod & method,
+        const ContentAddressMethod & method,
         const HashType & hashType,
         const StorePath & path);
 
-    FixedOutputHash hashCAPath(
+    ContentAddress hashCAPath(
-        const FileIngestionMethod & method,
+        const ContentAddressMethod & method,
         const HashType & hashType,
         const Path & path,
         const std::string_view pathHash

src/libstore/make-content-addressed.cc

@@ -52,10 +52,8 @@ std::map<StorePath, StorePath> makeContentAddressed(
             dstStore,
             path.name(),
             FixedOutputInfo {
-                .hash = {
+                .method = FileIngestionMethod::Recursive,
-                    .method = FileIngestionMethod::Recursive,
+                .hash = narModuloHash,
-                    .hash = narModuloHash,
-                },
                 .references = std::move(refs),
             },
             Hash::dummy,

src/libstore/path-info.cc

@@ -29,14 +29,14 @@ std::optional<ContentAddressWithReferences> ValidPathInfo::contentAddressWithRef
         return std::nullopt;
 
     return std::visit(overloaded {
-        [&](const TextHash & th) -> ContentAddressWithReferences {
+        [&](const TextIngestionMethod &) -> ContentAddressWithReferences {
             assert(references.count(path) == 0);
             return TextInfo {
-                .hash = th,
+                .hash = ca->hash,
                 .references = references,
             };
         },
-        [&](const FixedOutputHash & foh) -> ContentAddressWithReferences {
+        [&](const FileIngestionMethod & m2) -> ContentAddressWithReferences {
             auto refs = references;
             bool hasSelfReference = false;
             if (refs.count(path)) {
@@ -44,14 +44,15 @@ std::optional<ContentAddressWithReferences> ValidPathInfo::contentAddressWithRef
                 refs.erase(path);
             }
             return FixedOutputInfo {
-                .hash = foh,
+                .method = m2,
+                .hash = ca->hash,
                 .references = {
                     .others = std::move(refs),
                     .self = hasSelfReference,
                 },
             };
         },
-    }, ca->raw);
+    }, ca->method.raw);
 }
 
 bool ValidPathInfo::isContentAddressed(const Store & store) const
@@ -110,13 +111,19 @@ ValidPathInfo::ValidPathInfo(
     std::visit(overloaded {
         [this](TextInfo && ti) {
             this->references = std::move(ti.references);
-            this->ca = std::move((TextHash &&) ti);
+            this->ca = ContentAddress {
+                .method = TextIngestionMethod {},
+                .hash = std::move(ti.hash),
+            };
         },
         [this](FixedOutputInfo && foi) {
             this->references = std::move(foi.references.others);
             if (foi.references.self)
                 this->references.insert(path);
-            this->ca = std::move((FixedOutputHash &&) foi);
+            this->ca = ContentAddress {
+                .method = std::move(foi.method),
+                .hash = std::move(foi.hash),
+            };
         },
     }, std::move(ca).raw);
 }

src/libstore/store-api.cc

@@ -184,15 +184,15 @@ static std::string makeType(
 
 StorePath Store::makeFixedOutputPath(std::string_view name, const FixedOutputInfo & info) const
 {
-    if (info.hash.hash.type == htSHA256 && info.hash.method == FileIngestionMethod::Recursive) {
+    if (info.hash.type == htSHA256 && info.method == FileIngestionMethod::Recursive) {
-        return makeStorePath(makeType(*this, "source", info.references), info.hash.hash, name);
+        return makeStorePath(makeType(*this, "source", info.references), info.hash, name);
     } else {
         assert(info.references.size() == 0);
         return makeStorePath("output:out",
             hashString(htSHA256,
                 "fixed:out:"
-                + makeFileIngestionPrefix(info.hash.method)
+                + makeFileIngestionPrefix(info.method)
-                + info.hash.hash.to_string(Base16, true) + ":"),
+                + info.hash.to_string(Base16, true) + ":"),
             name);
     }
 }
@@ -200,13 +200,13 @@ StorePath Store::makeFixedOutputPath(std::string_view name, const FixedOutputInf
 
 StorePath Store::makeTextPath(std::string_view name, const TextInfo & info) const
 {
-    assert(info.hash.hash.type == htSHA256);
+    assert(info.hash.type == htSHA256);
     return makeStorePath(
         makeType(*this, "text", StoreReferences {
             .others = info.references,
             .self = false,
         }),
-        info.hash.hash,
+        info.hash,
         name);
 }
 
@@ -232,10 +232,8 @@ std::pair<StorePath, Hash> Store::computeStorePathForPath(std::string_view name,
         ? hashPath(hashAlgo, srcPath, filter).first
         : hashFile(hashAlgo, srcPath);
     FixedOutputInfo caInfo {
-        .hash = {
+        .method = method,
-            .method = method,
+        .hash = h,
-            .hash = h,
-        },
         .references = {},
     };
     return std::make_pair(makeFixedOutputPath(name, caInfo), h);
@@ -248,8 +246,8 @@ StorePath Store::computeStorePathForText(
     const StorePathSet & references) const
 {
     return makeTextPath(name, TextInfo {
-        { .hash = hashString(htSHA256, s) },
+        .hash = hashString(htSHA256, s),
-        references,
+        .references = references,
     });
 }
 
@@ -441,10 +439,8 @@ ValidPathInfo Store::addToStoreSlow(std::string_view name, const Path & srcPath,
         *this,
         name,
         FixedOutputInfo {
-            .hash = {
+            .method = method,
-                .method = method,
+            .hash = hash,
-                .hash = hash,
-            },
             .references = {},
         },
         narHash,

src/libstore/tests/derivation.cc

@@ -81,7 +81,7 @@ TEST_JSON(DerivationTest, caFixedFlat,
         "path": "/nix/store/rhcg9h16sqvlbpsa6dqm57sbr2al6nzg-drv-name-output-name"
     })",
     (DerivationOutput::CAFixed {
-        .ca = FixedOutputHash {
+        .ca = {
             .method = FileIngestionMethod::Flat,
             .hash = Hash::parseAnyPrefixed("sha256-iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="),
         },
@@ -95,7 +95,7 @@ TEST_JSON(DerivationTest, caFixedNAR,
         "path": "/nix/store/c015dhfh5l0lp6wxyvdn7bmwhbbr6hr9-drv-name-output-name"
     })",
     (DerivationOutput::CAFixed {
-        .ca = FixedOutputHash {
+        .ca = {
             .method = FileIngestionMethod::Recursive,
             .hash = Hash::parseAnyPrefixed("sha256-iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="),
         },
@@ -109,7 +109,7 @@ TEST_JSON(DynDerivationTest, caFixedText,
         "path": "/nix/store/6s1zwabh956jvhv4w9xcdb5jiyanyxg1-drv-name-output-name"
     })",
     (DerivationOutput::CAFixed {
-        .ca = TextHash {
+        .ca = {
             .hash = Hash::parseAnyPrefixed("sha256-iUUXyRY8iW7DGirb0zwGgf1fRbLA7wimTJKgP7l/OQ8="),
         },
     }),

src/nix-store/nix-store.cc

@@ -220,10 +220,8 @@ static void opPrintFixedPath(Strings opFlags, Strings opArgs)
     std::string name = *i++;
 
     cout << fmt("%s\n", store->printStorePath(store->makeFixedOutputPath(name, FixedOutputInfo {
-        .hash = {
+        .method = method,
-            .method = method,
+        .hash = Hash::parseAny(hash, hashAlgo),
-            .hash = Hash::parseAny(hash, hashAlgo),
-        },
         .references = {},
     })));
 }

src/nix/add-to-store.cc

@@ -45,10 +45,8 @@ struct CmdAddToStore : MixDryRun, StoreCommand
             *store,
             std::move(*namePart),
             FixedOutputInfo {
-                .hash = {
+                .method = std::move(ingestionMethod),
-                    .method = std::move(ingestionMethod),
+                .hash = std::move(hash),
-                    .hash = std::move(hash),
-                },
                 .references = {},
             },
             narHash,

src/nix/prefetch.cc

@@ -71,10 +71,8 @@ std::tuple<StorePath, Hash> prefetchFile(
     if (expectedHash) {
         hashType = expectedHash->type;
         storePath = store->makeFixedOutputPath(*name, FixedOutputInfo {
-            .hash = {
+            .method = ingestionMethod,
-                .method = ingestionMethod,
+            .hash = *expectedHash,
-                .hash = *expectedHash,
-            },
             .references = {},
         });
         if (store->isValidPath(*storePath))
@@ -127,7 +125,7 @@ std::tuple<StorePath, Hash> prefetchFile(
         auto info = store->addToStoreSlow(*name, tmpFile, ingestionMethod, hashType, expectedHash);
         storePath = info.path;
         assert(info.ca);
-        hash = info.ca->getHash();
+        hash = info.ca->hash;
     }
 
     return {storePath.value(), hash.value()};

src/nix/profile.cc

@@ -222,10 +222,8 @@ struct ProfileManifest
             *store,
             "profile",
             FixedOutputInfo {
-                .hash = {
+                .method = FileIngestionMethod::Recursive,
-                    .method = FileIngestionMethod::Recursive,
+                .hash = narHash,
-                    .hash = narHash,
-                },
                 .references = {
                     .others = std::move(references),
                     // profiles never refer to themselves