From 1ad6394b33b5e627c27bc26247f8a5e1d7d81ce1 Mon Sep 17 00:00:00 2001
From: Carlo Nucera <carlo.nucera@protonmail.com>
Date: Wed, 5 Aug 2020 15:11:49 -0400
Subject: [PATCH] Add Hash::dummy to signal default value

We did this in the same spirit of the dummy value that's present in
libstore/path.hh
---
 src/libstore/legacy-ssh-store.cc | 2 +-
 src/libstore/path-info.hh        | 4 ++--
 src/libutil/hash.cc              | 2 ++
 src/libutil/hash.hh              | 2 ++
 4 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/libstore/legacy-ssh-store.cc b/src/libstore/legacy-ssh-store.cc
index ed57a188b..f0f5ec626 100644
--- a/src/libstore/legacy-ssh-store.cc
+++ b/src/libstore/legacy-ssh-store.cc
@@ -113,7 +113,7 @@ struct LegacySSHStore : public Store
 
             if (GET_PROTOCOL_MINOR(conn->remoteVersion) >= 4) {
                 auto s = readString(conn->from);
-                info->narHash = s.empty() ? Hash(htSHA256) : Hash::parseAnyPrefixed(s);
+                info->narHash = s.empty() ? Hash::dummy : Hash::parseAnyPrefixed(s);
                 info->ca = parseContentAddressOpt(readString(conn->from));
                 info->sigs = readStrings<StringSet>(conn->from);
             }
diff --git a/src/libstore/path-info.hh b/src/libstore/path-info.hh
index ba154dab7..15484717e 100644
--- a/src/libstore/path-info.hh
+++ b/src/libstore/path-info.hh
@@ -100,8 +100,8 @@ struct ValidPathInfo
 
     ValidPathInfo(const ValidPathInfo & other) = default;
 
-    ValidPathInfo(StorePath && path) : path(std::move(path)), narHash(Hash(htSHA256)) { };
-    ValidPathInfo(const StorePath & path) : path(path), narHash(Hash(htSHA256)) { };
+    ValidPathInfo(StorePath && path) : path(std::move(path)), narHash(Hash::dummy) { };
+    ValidPathInfo(const StorePath & path) : path(path), narHash(Hash::dummy) { };
 
     virtual ~ValidPathInfo() { }
 };
diff --git a/src/libutil/hash.cc b/src/libutil/hash.cc
index dfb3668f1..4a94f0dfd 100644
--- a/src/libutil/hash.cc
+++ b/src/libutil/hash.cc
@@ -136,6 +136,8 @@ std::string Hash::to_string(Base base, bool includeType) const
     return s;
 }
 
+Hash Hash::dummy(htSHA256);
+
 Hash Hash::parseSRI(std::string_view original) {
     auto rest = original;
 
diff --git a/src/libutil/hash.hh b/src/libutil/hash.hh
index 00ce7bb6f..0520c6022 100644
--- a/src/libutil/hash.hh
+++ b/src/libutil/hash.hh
@@ -105,6 +105,8 @@ public:
         assert(type == htSHA1);
         return std::string(to_string(Base16, false), 0, 7);
     }
+
+    static Hash dummy;
 };
 
 /* Helper that defaults empty hashes to the 0 hash. */