Remove `HashType::Unknown`

Instead, `Hash` uses `std::optional<HashType>`. In the future, we may
also make `Hash` itself require a known hash type, encoraging people to
use `std::optional<Hash>` instead.

5 files changed, 7 insertions, 9 deletions

diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index ae7ba6549..b93855f79 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -3726,8 +3726,8 @@ void DerivationGoal::registerOutputs()
             /* Check the hash. In hash mode, move the path produced by
                the derivation to its content-addressed location. */
             Hash h2 = outputHashMode == FileIngestionMethod::Recursive
-                ? hashPath(h.type, actualPath).first
-                : hashFile(h.type, actualPath);
+                ? hashPath(*h.type, actualPath).first
+                : hashFile(*h.type, actualPath);
 
             auto dest = worker.store.makeFixedOutputPath(outputHashMode, h2, i.second.path.name());
 
@@ -4999,7 +4999,7 @@ bool Worker::pathContentsGood(const StorePath & path)
     if (!pathExists(store.printStorePath(path)))
         res = false;
     else {
-        HashResult current = hashPath(info->narHash.type, store.printStorePath(path));
+        HashResult current = hashPath(*info->narHash.type, store.printStorePath(path));
         Hash nullHash(HashType::SHA256);
         res = info->narHash == nullHash || info->narHash == current.first;
     }
diff --git a/src/libstore/builtins/fetchurl.cc b/src/libstore/builtins/fetchurl.cc
index b70e960f8..831431437 100644
--- a/src/libstore/builtins/fetchurl.cc
+++ b/src/libstore/builtins/fetchurl.cc
@@ -65,7 +65,7 @@ void builtinFetchurl(const BasicDerivation & drv, const std::string & netrcData)
                 if (!hasSuffix(hashedMirror, "/")) hashedMirror += '/';
                 auto ht = parseHashType(getAttr("outputHashAlgo"));
                 auto h = Hash(getAttr("outputHash"), ht);
-                fetch(hashedMirror + printHashType(h.type) + "/" + h.to_string(Base::Base16, false));
+                fetch(hashedMirror + printHashType(*h.type) + "/" + h.to_string(Base::Base16, false));
                 return;
             } catch (Error & e) {
                 debug(e.what());
diff --git a/src/libstore/derivations.cc b/src/libstore/derivations.cc
index a90c9b86c..d7b677185 100644
--- a/src/libstore/derivations.cc
+++ b/src/libstore/derivations.cc
@@ -20,8 +20,6 @@ void DerivationOutput::parseHashInfo(FileIngestionMethod & recursive, Hash & has
     }
 
     HashType hashType = parseHashType(algo);
-    if (hashType == HashType::Unknown)
-        throw Error("unknown hash algorithm '%s'", algo);
 
     hash = Hash(this->hash, hashType);
 }
diff --git a/src/libstore/export-import.cc b/src/libstore/export-import.cc
index 8a5e9d08e..e96b5610a 100644
--- a/src/libstore/export-import.cc
+++ b/src/libstore/export-import.cc
@@ -54,7 +54,7 @@ void Store::exportPath(const StorePath & path, Sink & sink)
        filesystem corruption from spreading to other machines.
        Don't complain if the stored hash is zero (unknown). */
     Hash hash = hashAndWriteSink.currentHash();
-    if (hash != info->narHash && info->narHash != Hash(info->narHash.type))
+    if (hash != info->narHash && info->narHash != Hash(*info->narHash.type))
         throw Error("hash of path '%s' has changed from '%s' to '%s'!",
             printStorePath(path), info->narHash.to_string(), hash.to_string());
 
diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 7f0d5af25..5b18ebf95 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -1264,9 +1264,9 @@ bool LocalStore::verifyStore(bool checkContents, RepairFlag repair)
 
                 std::unique_ptr<AbstractHashSink> hashSink;
                 if (info->ca == "" || !info->references.count(info->path))
-                    hashSink = std::make_unique<HashSink>(info->narHash.type);
+                    hashSink = std::make_unique<HashSink>(*info->narHash.type);
                 else
-                    hashSink = std::make_unique<HashModuloSink>(info->narHash.type, storePathToHash(printStorePath(info->path)));
+                    hashSink = std::make_unique<HashModuloSink>(*info->narHash.type, storePathToHash(printStorePath(info->path)));
 
                 dumpPath(Store::toRealPath(i), *hashSink);
                 auto current = hashSink->finish();