From 3049f31d2824b95c8a2e13c6b919847de6bd0705 Mon Sep 17 00:00:00 2001
From: edef <edef@edef.eu>
Date: Fri, 7 Aug 2020 15:27:27 +0000
Subject: [PATCH] chore(3p/nix): don't optional-wrap
 EvalState::file_access_trace_fn further

std::function has a natural null we can't eliminate anyway, so this was
effectively std::optional<std::optional<non_nullable_function>>.

Change-Id: If99f139146021edb25d133dad7f0f6e125ef53df
Reviewed-on: https://cl.tvl.fyi/c/depot/+/1688
Tested-by: BuildkiteCI
Reviewed-by: kanepyork <rikingcoding@gmail.com>
Reviewed-by: glittershark <grfn@gws.fyi>
---
 third_party/nix/src/libexpr/eval.cc | 4 ++--
 third_party/nix/src/libexpr/eval.hh | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/third_party/nix/src/libexpr/eval.cc b/third_party/nix/src/libexpr/eval.cc
index f068b6ba6..3ecd990da 100644
--- a/third_party/nix/src/libexpr/eval.cc
+++ b/third_party/nix/src/libexpr/eval.cc
@@ -1821,9 +1821,9 @@ void EvalState::printStats() {
 }
 
 void EvalState::TraceFileAccess(const Path& realPath) {
-  if (file_access_trace_fn.has_value()) {
+  if (file_access_trace_fn) {
     if (last_traced_file != realPath) {
-      (*file_access_trace_fn)(realPath);
+      file_access_trace_fn(realPath);
       // Basic deduplication.
       last_traced_file = std::string(realPath);
     }
diff --git a/third_party/nix/src/libexpr/eval.hh b/third_party/nix/src/libexpr/eval.hh
index c244b6eec..d2ff99c9f 100644
--- a/third_party/nix/src/libexpr/eval.hh
+++ b/third_party/nix/src/libexpr/eval.hh
@@ -303,8 +303,7 @@ class EvalState : public gc {
 
   bool countCalls;
 
-  std::optional<std::function<void(const Path&)>> file_access_trace_fn =
-      std::nullopt;
+  std::function<void(const Path&)> file_access_trace_fn = nullptr;
   Path last_traced_file = "";
 
   typedef std::map<Symbol, size_t> PrimOpCalls;