From 91e89628fdfe7b08e0f61b8531edd31833330e04 Mon Sep 17 00:00:00 2001
From: Rebecca Turner <rbt@sent.as>
Date: Thu, 22 Feb 2024 17:18:27 -0800
Subject: [PATCH] Make `addErrorTrace` variadic

---
 src/libexpr/eval.cc | 12 +++++++-----
 src/libexpr/eval.hh |  6 ++++--
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 54b1125ce..c4e163b08 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -806,14 +806,16 @@ void EvalState::runDebugRepl(const Error * error, const Env & env, const Expr &
     }
 }
 
-void EvalState::addErrorTrace(Error & e, const char * s, const std::string & s2) const
+template<typename... Args>
+void EvalState::addErrorTrace(Error & e, const Args & ... formatArgs) const
 {
-    e.addTrace(nullptr, s, s2);
+    e.addTrace(nullptr, HintFmt(formatArgs...));
 }
 
-void EvalState::addErrorTrace(Error & e, const PosIdx pos, const char * s, const std::string & s2) const
+template<typename... Args>
+void EvalState::addErrorTrace(Error & e, const PosIdx pos, const Args & ... formatArgs) const
 {
-    e.addTrace(positions[pos], HintFmt(s, s2));
+    e.addTrace(positions[pos], HintFmt(formatArgs...));
 }
 
 template<typename... Args>
@@ -1588,7 +1590,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                         lambda.name
                         ? concatStrings("'", symbols[lambda.name], "'")
                         : "anonymous lambda");
-                    if (pos) addErrorTrace(e, pos, "from call site%s", "");
+                    if (pos) addErrorTrace(e, pos, "from call site");
                 }
                 throw;
             }
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 80b583eb1..01abd4eb1 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -432,10 +432,12 @@ public:
     std::string_view forceString(Value & v, NixStringContext & context, const PosIdx pos, std::string_view errorCtx);
     std::string_view forceStringNoCtx(Value & v, const PosIdx pos, std::string_view errorCtx);
 
+    template<typename... Args>
     [[gnu::noinline]]
-    void addErrorTrace(Error & e, const char * s, const std::string & s2) const;
+    void addErrorTrace(Error & e, const Args & ... formatArgs) const;
+    template<typename... Args>
     [[gnu::noinline]]
-    void addErrorTrace(Error & e, const PosIdx pos, const char * s, const std::string & s2) const;
+    void addErrorTrace(Error & e, const PosIdx pos, const Args & ... formatArgs) const;
 
 public:
     /**