From c484a67914fe16c4f2f6e7779baf4bdfe6405a22 Mon Sep 17 00:00:00 2001
From: Ben Burdette <bburdette@gmail.com>
Date: Mon, 29 Jun 2020 15:46:21 -0600
Subject: [PATCH] trace formatting

---
 src/libutil/error.cc    | 57 +++++++++++++++++++++++------------------
 src/nix/installables.cc |  2 +-
 2 files changed, 33 insertions(+), 26 deletions(-)

diff --git a/src/libutil/error.cc b/src/libutil/error.cc
index 0199ee5f8..02eb3f7cb 100644
--- a/src/libutil/error.cc
+++ b/src/libutil/error.cc
@@ -328,41 +328,48 @@ std::ostream& showErrorInfo(std::ostream &out, const ErrorInfo &einfo, bool show
     }
 
     // traces
-    if (showTrace) {
+    if (showTrace && !einfo.traces.empty())
+    {
+        const string tracetitle(" show-trace output ");
+
+        int fill = errwidth - tracetitle.length();
+        int lw = 0;
+        int rw = 0;
+        const int min_dashes = 3;
+        if (fill > min_dashes * 2) {
+            if (fill % 2 != 0) {
+                lw = fill / 2;
+                rw = lw + 1;
+            }
+            else
+            {
+                lw = rw = fill / 2;
+            }
+        }
+        else
+            lw = rw = min_dashes;
+
+        if (nl)
+            out << std::endl << prefix;
+
+        out << ANSI_BLUE << std::string(lw, '-') << tracetitle << std::string(rw, '-') << ANSI_NORMAL;
+
         for (auto iter = einfo.traces.rbegin(); iter != einfo.traces.rend(); ++iter)
         {
             try {
-                if (nl)
-                    out << std::endl << prefix;
-
-                const string tracetitle(" show-trace output ");
-
-                int fill = errwidth - tracetitle.length();
-                int lw = 0;
-                int rw = 0;
-                const int min_dashes = 3;
-                if (fill > min_dashes * 2) {
-                    if (fill % 2 != 0) {
-                        lw = fill / 2;
-                        rw = lw + 1;
-                    }
-                    else
-                    {
-                        lw = rw = fill / 2;
-                    }
-                }
-                else
-                    lw = rw = min_dashes;
-
-                out << ANSI_BLUE << std::string(lw, '-') << tracetitle << std::string(rw, '-') << std::endl << prefix;
-                out << iter->hint.str() <<  std::endl;
+                out << std::endl << prefix;
+                out << ANSI_BLUE << "trace: " << ANSI_NORMAL << iter->hint.str() <<  std::endl;
 
                 auto pos = *iter->pos;
                 printAtPos(prefix, pos, out);
                 nl = true;
                 auto loc = getCodeLines(pos);
                 if (loc.has_value())
+                {
+                    out << std::endl;
                     printCodeLines(out, prefix, pos, *loc);
+                    out << std::endl;
+                }
             } catch(const std::bad_optional_access& e) {
                 out << iter->hint.str() << std::endl;
             }
diff --git a/src/nix/installables.cc b/src/nix/installables.cc
index 166ba167f..708a0dc88 100644
--- a/src/nix/installables.cc
+++ b/src/nix/installables.cc
@@ -212,7 +212,7 @@ std::string attrRegex = R"([A-Za-z_][A-Za-z0-9-_+]*)";
 static std::regex attrPathRegex(fmt(R"(%1%(\.%1%)*)", attrRegex));
 
 static std::vector<std::shared_ptr<Installable>> parseInstallables(
-    SourceExprCommand & cmd, ref<Store> store, std::vetor<std::string> ss, bool useDefaultInstallables)
+    SourceExprCommand & cmd, ref<Store> store, std::vector<std::string> ss, bool useDefaultInstallables)
 {
     std::vector<std::shared_ptr<Installable>> result;