From 3629b0585aaf13f7d25510c55ca06611cb2135af Mon Sep 17 00:00:00 2001
From: Ben Burdette <bburdette@gmail.com>
Date: Wed, 1 Jul 2020 11:49:01 -0600
Subject: [PATCH] don't include errpos for addErrorContext

---
 src/libexpr/primops.cc | 3 +--
 src/libutil/error.cc   | 7 ++++---
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 4cc3718e3..dec917b38 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -471,8 +471,7 @@ static void prim_addErrorContext(EvalState & state, const Pos & pos, Value * * a
         v = *args[1];
     } catch (Error & e) {
         PathSet context;
-        // TODO: is this right, include this pos??  Test it.  esp with LOC.
-        e.addTrace(pos, "%1%", state.coerceToString(pos, *args[0], context));
+        e.addTrace(std::nullopt, state.coerceToString(pos, *args[0], context));
         throw;
     }
 }
diff --git a/src/libutil/error.cc b/src/libutil/error.cc
index 78e2a5ea2..3a9b924f2 100644
--- a/src/libutil/error.cc
+++ b/src/libutil/error.cc
@@ -305,7 +305,7 @@ std::ostream& showErrorInfo(std::ostream &out, const ErrorInfo &einfo, bool show
         nl = true;
     }
 
-    if (einfo.errPos.has_value()) {
+    if (einfo.errPos.has_value() && (*einfo.errPos)) {
         auto loc = getCodeLines(*einfo.errPos);
 
         // lines of code.
@@ -359,9 +359,10 @@ std::ostream& showErrorInfo(std::ostream &out, const ErrorInfo &einfo, bool show
                 out << ANSI_BLUE << "trace: " << ANSI_NORMAL << iter->hint.str();
 
                 nl = true;
-                auto pos = *iter->pos;
-                if (pos) {
+                if (*iter->pos) {
+                    auto pos = iter->pos.value();
                     out << std::endl << prefix;
+
                     printAtPos(prefix, pos, out);
                     auto loc = getCodeLines(pos);
                     if (loc.has_value())