From 46cb15df9b3501ca631779fa7d5c6299c1c17b53 Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <edolstra@gmail.com>
Date: Fri, 19 Apr 2019 11:16:14 +0200
Subject: [PATCH] Fix assertion failure in FlakeRef::to_string()

---
 src/libexpr/primops/fetchGit.cc | 3 ++-
 src/libexpr/primops/fetchGit.hh | 1 +
 src/libexpr/primops/flake.cc    | 2 +-
 src/libexpr/primops/flakeref.cc | 2 +-
 4 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/libexpr/primops/fetchGit.cc b/src/libexpr/primops/fetchGit.cc
index 391308224..40975d8d8 100644
--- a/src/libexpr/primops/fetchGit.cc
+++ b/src/libexpr/primops/fetchGit.cc
@@ -39,6 +39,7 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
                files. */
 
             GitInfo gitInfo;
+            gitInfo.ref = "HEAD";
             gitInfo.rev = "0000000000000000000000000000000000000000";
             gitInfo.shortRev = std::string(gitInfo.rev, 0, 7);
 
@@ -67,7 +68,6 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
 
         // clean working tree, but no ref or rev specified.  Use 'HEAD'.
         rev = chomp(runProgram("git", true, { "-C", uri, "rev-parse", "HEAD" }));
-        ref = "HEAD"s;
     }
 
     if (!ref) ref = "HEAD"s;
@@ -127,6 +127,7 @@ GitInfo exportGit(ref<Store> store, const std::string & uri,
 
     // FIXME: check whether rev is an ancestor of ref.
     GitInfo gitInfo;
+    gitInfo.ref = *ref;
     gitInfo.rev = rev != "" ? rev : chomp(readFile(localRefFile));
     gitInfo.shortRev = std::string(gitInfo.rev, 0, 7);
 
diff --git a/src/libexpr/primops/fetchGit.hh b/src/libexpr/primops/fetchGit.hh
index 60c439426..5937bdcc0 100644
--- a/src/libexpr/primops/fetchGit.hh
+++ b/src/libexpr/primops/fetchGit.hh
@@ -9,6 +9,7 @@ namespace nix {
 struct GitInfo
 {
     Path storePath;
+    std::string ref;
     std::string rev;
     std::string shortRev;
     std::optional<uint64_t> revCount;
diff --git a/src/libexpr/primops/flake.cc b/src/libexpr/primops/flake.cc
index 2415faf5e..1149efaac 100644
--- a/src/libexpr/primops/flake.cc
+++ b/src/libexpr/primops/flake.cc
@@ -237,8 +237,8 @@ static FlakeSourceInfo fetchFlake(EvalState & state, const FlakeRef flakeRef, bo
         info.storePath = gitInfo.storePath;
         info.rev = Hash(gitInfo.rev, htSHA1);
         info.revCount = gitInfo.revCount;
+        info.flakeRef.ref = gitInfo.ref;
         info.flakeRef.rev = info.rev;
-        // FIXME: ensure info.flakeRef.ref is set.
         return info;
     }
 
diff --git a/src/libexpr/primops/flakeref.cc b/src/libexpr/primops/flakeref.cc
index 973987469..97f31377a 100644
--- a/src/libexpr/primops/flakeref.cc
+++ b/src/libexpr/primops/flakeref.cc
@@ -128,7 +128,7 @@ std::string FlakeRef::to_string() const
     }
 
     else if (auto refData = std::get_if<FlakeRef::IsGit>(&data)) {
-        assert(ref || !rev);
+        assert(!rev || ref);
         string = refData->uri;
     }