From cdc23866444b1ef863f917ec0adaaa9bec31126b Mon Sep 17 00:00:00 2001
From: Matthew Bauer <mjbauer95@gmail.com>
Date: Thu, 30 Jul 2020 16:40:21 -0500
Subject: [PATCH] Make expectedHash optional in prim_path

This fixes an error found in builtins.path that looks like:

store path mismatch in (possibly filtered) path added from '/private/tmp/nix-shell.CyXViH/nix-test/filter-source/filterin'

when no hash is specified
---
 src/libexpr/primops.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index a98cadc80..05d499d1f 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -1199,7 +1199,7 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
     string name;
     Value * filterFun = nullptr;
     auto method = FileIngestionMethod::Recursive;
-    Hash expectedHash(htSHA256);
+    std::optional<Hash> expectedHash;
 
     for (auto & attr : *args[0]->attrs) {
         const string & n(attr.name);