Use "raw pattern" for content address types

We weren't because this ancient PR predated it!

This is actually a new version of the pattern which addresses some
issues identified in #7479.

14 files changed, 117 insertions, 86 deletions

diff --git a/src/libstore/build/local-derivation-goal.cc b/src/libstore/build/local-derivation-goal.cc
index caa15ab04..4fb7aa9d8 100644
--- a/src/libstore/build/local-derivation-goal.cc
+++ b/src/libstore/build/local-derivation-goal.cc
@@ -2508,7 +2508,7 @@ DrvOutputs LocalDerivationGoal::registerOutputs()
                 /* Check wanted hash */
                 const Hash & wanted = dof.hash.hash;
                 assert(newInfo0.ca);
-                auto got = getContentAddressHash(*newInfo0.ca);
+                auto got = newInfo0.ca->getHash();
                 if (wanted != got) {
                     /* Throw an error after registering the path as
                        valid. */
diff --git a/src/libstore/build/substitution-goal.cc b/src/libstore/build/substitution-goal.cc
index 87fed495c..190fb455a 100644
--- a/src/libstore/build/substitution-goal.cc
+++ b/src/libstore/build/substitution-goal.cc
@@ -97,7 +97,7 @@ void PathSubstitutionGoal::tryNext()
     if (ca) {
         subPath = sub->makeFixedOutputPathFromCA(
             std::string { storePath.name() },
-            caWithoutRefs(*ca));
+            ContentAddressWithReferences::withoutRefs(*ca));
         if (sub->storeDir == worker.store.storeDir)
             assert(subPath == storePath);
     } else if (sub->storeDir != worker.store.storeDir) {
diff --git a/src/libstore/content-address.cc b/src/libstore/content-address.cc
index 64daea0d4..055b216db 100644
--- a/src/libstore/content-address.cc
+++ b/src/libstore/content-address.cc
@@ -9,7 +9,6 @@ std::string FixedOutputHash::printMethodAlgo() const
     return makeFileIngestionPrefix(method) + printHashType(hash.type);
 }
 
-
 std::string makeFileIngestionPrefix(FileIngestionMethod m)
 {
     switch (m) {
@@ -22,35 +21,35 @@ std::string makeFileIngestionPrefix(FileIngestionMethod m)
     }
 }
 
-std::string renderContentAddress(ContentAddress ca)
+std::string ContentAddress::render() const
 {
     return std::visit(overloaded {
-        [](TextHash & th) {
+        [](const TextHash & th) {
             return "text:"
                 + th.hash.to_string(Base32, true);
         },
-        [](FixedOutputHash & fsh) {
+        [](const FixedOutputHash & fsh) {
             return "fixed:"
                 + makeFileIngestionPrefix(fsh.method)
                 + fsh.hash.to_string(Base32, true);
         }
-    }, ca);
+    }, raw);
 }
 
-std::string renderContentAddressMethod(ContentAddressMethod cam)
+std::string ContentAddressMethod::render() const
 {
     return std::visit(overloaded {
-        [](TextHashMethod & th) {
+        [](const TextHashMethod & th) {
             return std::string{"text:"} + printHashType(htSHA256);
         },
-        [](FixedOutputHashMethod & fshm) {
+        [](const FixedOutputHashMethod & fshm) {
             return "fixed:" + makeFileIngestionPrefix(fshm.fileIngestionMethod) + printHashType(fshm.hashType);
         }
-    }, cam);
+    }, raw);
 }
 
-/*
-  Parses content address strings up to the hash.
+/**
+ * Parses content address strings up to the hash.
  */
 static ContentAddressMethod parseContentAddressMethodPrefix(std::string_view & rest)
 {
@@ -94,7 +93,7 @@ static ContentAddressMethod parseContentAddressMethodPrefix(std::string_view & r
         throw UsageError("content address prefix '%s' is unrecognized. Recogonized prefixes are 'text' or 'fixed'", prefix);
 }
 
-ContentAddress parseContentAddress(std::string_view rawCa) {
+ContentAddress ContentAddress::parse(std::string_view rawCa) {
     auto rest = rawCa;
 
     ContentAddressMethod caMethod = parseContentAddressMethodPrefix(rest);
@@ -112,10 +111,10 @@ ContentAddress parseContentAddress(std::string_view rawCa) {
                     .hash = Hash::parseNonSRIUnprefixed(rest, std::move(fohMethod.hashType)),
                 });
             },
-        }, caMethod);
+        }, caMethod.raw);
 }
 
-ContentAddressMethod parseContentAddressMethod(std::string_view caMethod)
+ContentAddressMethod ContentAddressMethod::parse(std::string_view caMethod)
 {
     std::string asPrefix = std::string{caMethod} + ":";
     // parseContentAddressMethodPrefix takes its argument by reference
@@ -123,26 +122,28 @@ ContentAddressMethod parseContentAddressMethod(std::string_view caMethod)
     return parseContentAddressMethodPrefix(asPrefixView);
 }
 
-std::optional<ContentAddress> parseContentAddressOpt(std::string_view rawCaOpt)
+std::optional<ContentAddress> ContentAddress::parseOpt(std::string_view rawCaOpt)
 {
-    return rawCaOpt == "" ? std::optional<ContentAddress>() : parseContentAddress(rawCaOpt);
+    return rawCaOpt == ""
+        ? std::nullopt
+        : std::optional { ContentAddress::parse(rawCaOpt) };
 };
 
 std::string renderContentAddress(std::optional<ContentAddress> ca)
 {
-    return ca ? renderContentAddress(*ca) : "";
+    return ca ? ca->render() : "";
 }
 
-Hash getContentAddressHash(const ContentAddress & ca)
+const Hash & ContentAddress::getHash() const
 {
     return std::visit(overloaded {
-        [](const TextHash & th) {
+        [](const TextHash & th) -> auto & {
             return th.hash;
         },
-        [](const FixedOutputHash & fsh) {
+        [](const FixedOutputHash & fsh) -> auto & {
             return fsh.hash;
         },
-    }, ca);
+    }, raw);
 }
 
 bool StoreReferences::empty() const
@@ -155,7 +156,7 @@ size_t StoreReferences::size() const
     return (self ? 1 : 0) + others.size();
 }
 
-ContentAddressWithReferences caWithoutRefs(const ContentAddress & ca) {
+ContentAddressWithReferences ContentAddressWithReferences::withoutRefs(const ContentAddress & ca) {
     return std::visit(overloaded {
         [&](const TextHash & h) -> ContentAddressWithReferences {
             return TextInfo {
@@ -169,7 +170,7 @@ ContentAddressWithReferences caWithoutRefs(const ContentAddress & ca) {
                 .references = {},
             };
         },
-    }, ca);
+    }, ca.raw);
 }
 
 }
diff --git a/src/libstore/content-address.hh b/src/libstore/content-address.hh
index d74d1ff4b..d1dd1256c 100644
--- a/src/libstore/content-address.hh
+++ b/src/libstore/content-address.hh
@@ -39,17 +39,16 @@ enum struct FileIngestionMethod : uint8_t {
     Recursive = true
 };
 
-struct FixedOutputHashMethod {
-  FileIngestionMethod fileIngestionMethod;
-  HashType hashType;
-};
-
 /**
  * Compute the prefix to the hash algorithm which indicates how the
  * files were ingested.
  */
 std::string makeFileIngestionPrefix(FileIngestionMethod m);
 
+struct FixedOutputHashMethod {
+  FileIngestionMethod fileIngestionMethod;
+  HashType hashType;
+};
 
 /**
  * An enumeration of all the ways we can serialize file system objects.
@@ -59,14 +58,25 @@ std::string makeFileIngestionPrefix(FileIngestionMethod m);
  * with info on references, and we have `ContentAddressWithReferences`,
  * as defined further below.
  */
-typedef std::variant<
-    TextHashMethod,
-    FixedOutputHashMethod
-> ContentAddressMethod;
+struct ContentAddressMethod
+{
+    typedef std::variant<
+        TextHashMethod,
+        FixedOutputHashMethod
+    > Raw;
 
-ContentAddressMethod parseContentAddressMethod(std::string_view rawCaMethod);
+    Raw raw;
+
+    /* The moral equivalent of `using Raw::Raw;` */
+    ContentAddressMethod(auto &&... arg)
+        : raw(std::forward<decltype(arg)>(arg)...)
+    { }
+
+    static ContentAddressMethod parse(std::string_view rawCaMethod);
+
+    std::string render() const;
+};
 
-std::string renderContentAddressMethod(ContentAddressMethod caMethod);
 
 /*
  * Mini content address
@@ -115,25 +125,41 @@ struct FixedOutputHash {
  * - ‘fixed:<r?>:<ht>:<h>’: For paths computed by
  *   Store::makeFixedOutputPath() / Store::addToStore().
  */
-typedef std::variant<
-    TextHash,
-    FixedOutputHash
-> ContentAddress;
+struct ContentAddress
+{
+    typedef std::variant<
+        TextHash,
+        FixedOutputHash
+    > Raw;
 
-/**
- * Compute the content-addressability assertion (ValidPathInfo::ca) for
- * paths created by Store::makeFixedOutputPath() / Store::addToStore().
- */
-std::string renderContentAddress(ContentAddress ca);
+    Raw raw;
 
-std::string renderContentAddress(std::optional<ContentAddress> ca);
+    /* The moral equivalent of `using Raw::Raw;` */
+    ContentAddress(auto &&... arg)
+        : raw(std::forward<decltype(arg)>(arg)...)
+    { }
 
-ContentAddress parseContentAddress(std::string_view rawCa);
+    /**
+     * Compute the content-addressability assertion (ValidPathInfo::ca) for
+     * paths created by Store::makeFixedOutputPath() / Store::addToStore().
+     */
+    std::string render() const;
 
-std::optional<ContentAddress> parseContentAddressOpt(std::string_view rawCaOpt);
+    static ContentAddress parse(std::string_view rawCa);
 
-Hash getContentAddressHash(const ContentAddress & ca);
+    static std::optional<ContentAddress> parseOpt(std::string_view rawCaOpt);
 
+    const Hash & getHash() const;
+};
+
+std::string renderContentAddress(std::optional<ContentAddress> ca);
+
+
+/*
+ * Full content address
+ *
+ * See the schema for store paths in store-api.cc
+ */
 
 /**
  * A set of references to other store objects.
@@ -167,12 +193,6 @@ struct StoreReferences {
     GENERATE_CMP(StoreReferences, me->self, me->others);
 };
 
-/*
- * Full content address
- *
- * See the schema for store paths in store-api.cc
- */
-
 // This matches the additional info that we need for makeTextPath
 struct TextInfo {
     TextHash hash;
@@ -200,15 +220,25 @@ struct FixedOutputInfo {
  *
  * A ContentAddress without a Hash.
  */
-typedef std::variant<
-    TextInfo,
-    FixedOutputInfo
-> ContentAddressWithReferences;
+struct ContentAddressWithReferences
+{
+    typedef std::variant<
+        TextInfo,
+        FixedOutputInfo
+    > Raw;
 
-/**
- * Create a ContentAddressWithReferences from a mere ContentAddress, by
- * assuming no references in all cases.
- */
-ContentAddressWithReferences caWithoutRefs(const ContentAddress &);
+    Raw raw;
+
+    /* The moral equivalent of `using Raw::Raw;` */
+    ContentAddressWithReferences(auto &&... arg)
+        : raw(std::forward<decltype(arg)>(arg)...)
+    { }
+
+    /**
+     * Create a ContentAddressWithReferences from a mere ContentAddress, by
+     * assuming no references in all cases.
+     */
+    static ContentAddressWithReferences withoutRefs(const ContentAddress &);
+};
 
 }
diff --git a/src/libstore/daemon.cc b/src/libstore/daemon.cc
index 656ad4587..0169eef1a 100644
--- a/src/libstore/daemon.cc
+++ b/src/libstore/daemon.cc
@@ -401,21 +401,21 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
             logger->startWork();
             auto pathInfo = [&]() {
                 // NB: FramedSource must be out of scope before logger->stopWork();
-                ContentAddressMethod contentAddressMethod = parseContentAddressMethod(camStr);
+                ContentAddressMethod contentAddressMethod = ContentAddressMethod::parse(camStr);
                 FramedSource source(from);
                 // TODO this is essentially RemoteStore::addCAToStore. Move it up to Store.
                 return std::visit(overloaded {
-                    [&](TextHashMethod &) {
+                    [&](const TextHashMethod &) {
                         // We could stream this by changing Store
                         std::string contents = source.drain();
                         auto path = store->addTextToStore(name, contents, refs, repair);
                         return store->queryPathInfo(path);
                     },
-                    [&](FixedOutputHashMethod & fohm) {
+                    [&](const FixedOutputHashMethod & fohm) {
                         auto path = store->addToStoreFromDump(source, name, fohm.fileIngestionMethod, fohm.hashType, repair, refs);
                         return store->queryPathInfo(path);
                     },
-                }, contentAddressMethod);
+                }, contentAddressMethod.raw);
             }();
             logger->stopWork();
 
@@ -880,7 +880,7 @@ static void performOp(TunnelLogger * logger, ref<Store> store,
         info.references = worker_proto::read(*store, from, Phantom<StorePathSet> {});
         from >> info.registrationTime >> info.narSize >> info.ultimate;
         info.sigs = readStrings<StringSet>(from);
-        info.ca = parseContentAddressOpt(readString(from));
+        info.ca = ContentAddress::parseOpt(readString(from));
         from >> repair >> dontCheckSigs;
         if (!trusted && dontCheckSigs)
             dontCheckSigs = false;
diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index 98322b045..a1c38d180 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -156,7 +156,7 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
                     throw Error("NAR hash is now mandatory");
                 info->narHash = Hash::parseAnyPrefixed(s);
             }
-            info->ca = parseContentAddressOpt(readString(conn->from));
+            info->ca = ContentAddress::parseOpt(readString(conn->from));
             info->sigs = readStrings<StringSet>(conn->from);
 
             auto s = readString(conn->from);
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index e1c7e387a..b49d5462b 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -944,7 +944,7 @@ std::shared_ptr<const ValidPathInfo> LocalStore::queryPathInfoInternal(State & s
     if (s) info->sigs = tokenizeString<StringSet>(s, " ");
 
     s = (const char *) sqlite3_column_text(state.stmts->QueryPathInfo, 7);
-    if (s) info->ca = parseContentAddressOpt(s);
+    if (s) info->ca = ContentAddress::parseOpt(s);
 
     /* Get the references. */
     auto useQueryReferences(state.stmts->QueryReferences.use()(info->id));
@@ -1150,7 +1150,7 @@ void LocalStore::querySubstitutablePathInfos(const StorePathCAMap & paths, Subst
             if (path.second) {
                 subPath = makeFixedOutputPathFromCA(
                     path.first.name(),
-                    caWithoutRefs(*path.second));
+                    ContentAddressWithReferences::withoutRefs(*path.second));
                 if (sub->storeDir == storeDir)
                     assert(subPath == path.first);
                 if (subPath != path.first)
@@ -1329,7 +1329,7 @@ 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)) {
+                if (auto foHash = std::get_if<FixedOutputHash>(&info.ca->raw)) {
                     auto actualFoHash = hashCAPath(
                         foHash->method,
                         foHash->hash.type,
@@ -1342,7 +1342,7 @@ void LocalStore::addToStore(const ValidPathInfo & info, Source & source,
                             actualFoHash.hash.to_string(Base32, true));
                     }
                 }
-                if (auto textHash = std::get_if<TextHash>(&*info.ca)) {
+                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",
diff --git a/src/libstore/nar-info-disk-cache.cc b/src/libstore/nar-info-disk-cache.cc
index 2645f468b..c7176d30f 100644
--- a/src/libstore/nar-info-disk-cache.cc
+++ b/src/libstore/nar-info-disk-cache.cc
@@ -273,7 +273,7 @@ public:
                 narInfo->deriver = StorePath(queryNAR.getStr(9));
             for (auto & sig : tokenizeString<Strings>(queryNAR.getStr(10), " "))
                 narInfo->sigs.insert(sig);
-            narInfo->ca = parseContentAddressOpt(queryNAR.getStr(11));
+            narInfo->ca = ContentAddress::parseOpt(queryNAR.getStr(11));
 
             return {oValid, narInfo};
         });
diff --git a/src/libstore/nar-info.cc b/src/libstore/nar-info.cc
index 071d8355e..274cd861c 100644
--- a/src/libstore/nar-info.cc
+++ b/src/libstore/nar-info.cc
@@ -74,7 +74,7 @@ NarInfo::NarInfo(const Store & store, const std::string & s, const std::string &
         else if (name == "CA") {
             if (ca) throw corrupt();
             // FIXME: allow blank ca or require skipping field?
-            ca = parseContentAddressOpt(value);
+            ca = ContentAddress::parseOpt(value);
         }
 
         pos = eol + 1;
diff --git a/src/libstore/path-info.cc b/src/libstore/path-info.cc
index 76cab63e0..e60d7abe0 100644
--- a/src/libstore/path-info.cc
+++ b/src/libstore/path-info.cc
@@ -49,7 +49,7 @@ std::optional<ContentAddressWithReferences> ValidPathInfo::contentAddressWithRef
                 },
             };
         },
-    }, *ca);
+    }, ca->raw);
 }
 
 bool ValidPathInfo::isContentAddressed(const Store & store) const
@@ -116,7 +116,7 @@ ValidPathInfo::ValidPathInfo(
                 this->references.insert(path);
             this->ca = std::move((FixedOutputHash &&) foi);
         },
-    }, std::move(ca));
+    }, std::move(ca).raw);
 }
 
 
@@ -136,7 +136,7 @@ ValidPathInfo ValidPathInfo::read(Source & source, const Store & store, unsigned
     if (format >= 16) {
         source >> info.ultimate;
         info.sigs = readStrings<StringSet>(source);
-        info.ca = parseContentAddressOpt(readString(source));
+        info.ca = ContentAddress::parseOpt(readString(source));
     }
     return info;
 }
diff --git a/src/libstore/remote-store.cc b/src/libstore/remote-store.cc
index d24d83117..ac98e76d2 100644
--- a/src/libstore/remote-store.cc
+++ b/src/libstore/remote-store.cc
@@ -44,7 +44,7 @@ void write(const Store & store, Sink & out, const StorePath & storePath)
 
 ContentAddress read(const Store & store, Source & from, Phantom<ContentAddress> _)
 {
-    return parseContentAddress(readString(from));
+    return ContentAddress::parse(readString(from));
 }
 
 void write(const Store & store, Sink & out, const ContentAddress & ca)
@@ -134,7 +134,7 @@ void write(const Store & store, Sink & out, const std::optional<StorePath> & sto
 
 std::optional<ContentAddress> read(const Store & store, Source & from, Phantom<std::optional<ContentAddress>> _)
 {
-    return parseContentAddressOpt(readString(from));
+    return ContentAddress::parseOpt(readString(from));
 }
 
 void write(const Store & store, Sink & out, const std::optional<ContentAddress> & caOpt)
@@ -545,7 +545,7 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
         conn->to
             << wopAddToStore
             << name
-            << renderContentAddressMethod(caMethod);
+            << caMethod.render();
         worker_proto::write(*this, conn->to, references);
         conn->to << repair;
 
@@ -603,7 +603,7 @@ ref<const ValidPathInfo> RemoteStore::addCAToStore(
                 }
 
             }
-        }, caMethod);
+        }, caMethod.raw);
         auto path = parseStorePath(readString(conn->from));
         // Release our connection to prevent a deadlock in queryPathInfo().
         conn_.reset();
diff --git a/src/libstore/store-api.cc b/src/libstore/store-api.cc
index fed38e2dd..78b0d907e 100644
--- a/src/libstore/store-api.cc
+++ b/src/libstore/store-api.cc
@@ -221,7 +221,7 @@ StorePath Store::makeFixedOutputPathFromCA(std::string_view name, const ContentA
         [&](const FixedOutputInfo & foi) {
             return makeFixedOutputPath(name, foi);
         }
-    }, ca);
+    }, ca.raw);
 }
 
 
diff --git a/src/nix-store/nix-store.cc b/src/nix-store/nix-store.cc
index 26febb6e3..3d2dc49fd 100644
--- a/src/nix-store/nix-store.cc
+++ b/src/nix-store/nix-store.cc
@@ -970,7 +970,7 @@ static void opServe(Strings opFlags, Strings opArgs)
                 info.references = worker_proto::read(*store, in, Phantom<StorePathSet> {});
                 in >> info.registrationTime >> info.narSize >> info.ultimate;
                 info.sigs = readStrings<StringSet>(in);
-                info.ca = parseContentAddressOpt(readString(in));
+                info.ca = ContentAddress::parseOpt(readString(in));
 
                 if (info.narSize == 0)
                     throw Error("narInfo is too old and missing the narSize field");
diff --git a/src/nix/prefetch.cc b/src/nix/prefetch.cc
index b06b8a320..56e7bbb6e 100644
--- a/src/nix/prefetch.cc
+++ b/src/nix/prefetch.cc
@@ -124,7 +124,7 @@ std::tuple<StorePath, Hash> prefetchFile(
         auto info = store->addToStoreSlow(*name, tmpFile, ingestionMethod, hashType, expectedHash);
         storePath = info.path;
         assert(info.ca);
-        hash = getContentAddressHash(*info.ca);
+        hash = info.ca->getHash();
     }
 
     return {storePath.value(), hash.value()};