15 files changed, 143 insertions, 116 deletions

diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index 2e2a17b14..83854df49 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -130,7 +130,7 @@ Pos findDerivationFilename(EvalState & state, Value & v, std::string what)
 
     Symbol file = state.symbols.create(filename);
 
-    return { file, lineno, 0 };
+    return { foFile, file, lineno, 0 };
 }
 
 
diff --git a/src/libexpr/attr-set.hh b/src/libexpr/attr-set.hh
index c601d09c2..7eaa16c59 100644
--- a/src/libexpr/attr-set.hh
+++ b/src/libexpr/attr-set.hh
@@ -78,7 +78,7 @@ public:
         if (!a)
             throw Error({
                 .hint = hintfmt("attribute '%s' missing", name),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
 
         return *a;
diff --git a/src/libexpr/eval-inline.hh b/src/libexpr/eval-inline.hh
index 3d544c903..30f6ec7db 100644
--- a/src/libexpr/eval-inline.hh
+++ b/src/libexpr/eval-inline.hh
@@ -11,7 +11,7 @@ LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s))
 {
     throw EvalError({
         .hint = hintfmt(s),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
@@ -25,7 +25,7 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const
 {
     throw TypeError({
         .hint = hintfmt(s, showType(v)),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index ba600ad0c..5510c64e9 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -544,7 +544,7 @@ LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const
 {
     throw EvalError({
         .hint = hintfmt(s, s2),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
@@ -557,7 +557,7 @@ LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const
 {
     throw EvalError({
         .hint = hintfmt(s, s2, s3),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
@@ -566,7 +566,7 @@ LocalNoInlineNoReturn(void throwEvalError(const Pos & p1, const char * s, const
     // p1 is where the error occurred; p2 is a position mentioned in the message.
     throw EvalError({
         .hint = hintfmt(s, sym, p2),
-        .nixCode = NixCode { .errPos = p1 }
+        .errPos = p1
     });
 }
 
@@ -574,7 +574,7 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s))
 {
     throw TypeError({
         .hint = hintfmt(s),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
@@ -587,7 +587,7 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const
 {
     throw TypeError({
         .hint = hintfmt(s, fun.showNamePos(), s2),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
@@ -595,7 +595,7 @@ LocalNoInlineNoReturn(void throwAssertionError(const Pos & pos, const char * s,
 {
     throw AssertionError({
         .hint = hintfmt(s, s1),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
@@ -603,23 +603,18 @@ LocalNoInlineNoReturn(void throwUndefinedVarError(const Pos & pos, const char *
 {
     throw UndefinedVarError({
         .hint = hintfmt(s, s1),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
-LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2))
+LocalNoInline(void addErrorTrace(Error & e, const char * s, const string & s2))
 {
-    e.addPrefix(format(s) % s2);
+    e.addTrace(std::nullopt, s, s2);
 }
 
-LocalNoInline(void addErrorPrefix(Error & e, const char * s, const ExprLambda & fun, const Pos & pos))
+LocalNoInline(void addErrorTrace(Error & e, const Pos & pos, const char * s, const string & s2))
 {
-    e.addPrefix(format(s) % fun.showNamePos() % pos);
-}
-
-LocalNoInline(void addErrorPrefix(Error & e, const char * s, const string & s2, const Pos & pos))
-{
-    e.addPrefix(format(s) % s2 % pos);
+    e.addTrace(pos, s, s2);
 }
 
 
@@ -838,7 +833,7 @@ void EvalState::evalFile(const Path & path_, Value & v, bool mustBeTrivial)
             throw Error("file '%s' must be an attribute set", path);
         eval(e, v);
     } catch (Error & e) {
-        addErrorPrefix(e, "while evaluating the file '%1%':\n", path2);
+        addErrorTrace(e, "while evaluating the file '%1%':", path2);
         throw;
     }
 
@@ -1088,8 +1083,8 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
 
     } catch (Error & e) {
         if (pos2 && pos2->file != state.sDerivationNix)
-            addErrorPrefix(e, "while evaluating the attribute '%1%' at %2%:\n",
-                showAttrPath(state, env, attrPath), *pos2);
+            addErrorTrace(e, *pos2, "while evaluating the attribute '%1%'",
+                showAttrPath(state, env, attrPath));
         throw;
     }
 
@@ -1257,11 +1252,15 @@ void EvalState::callFunction(Value & fun, Value & arg, Value & v, const Pos & po
 
     /* Evaluate the body.  This is conditional on showTrace, because
        catching exceptions makes this function not tail-recursive. */
-    if (settings.showTrace)
+    if (loggerSettings.showTrace.get())
         try {
             lambda.body->eval(*this, env2, v);
         } catch (Error & e) {
-            addErrorPrefix(e, "while evaluating %1%, called from %2%:\n", lambda, pos);
+            addErrorTrace(e, lambda.pos, "while evaluating %s", 
+              (lambda.name.set() 
+                  ? "'" + (string) lambda.name + "'" 
+                  : "anonymous lambdaction"));
+            addErrorTrace(e, pos, "from call site%s", "");
             throw;
         }
     else
@@ -1536,7 +1535,7 @@ void EvalState::forceValueDeep(Value & v)
                 try {
                     recurse(*i.value);
                 } catch (Error & e) {
-                    addErrorPrefix(e, "while evaluating the attribute '%1%' at %2%:\n", i.name, *i.pos);
+                    addErrorTrace(e, *i.pos, "while evaluating the attribute '%1%'", i.name);
                     throw;
                 }
         }
@@ -1979,7 +1978,7 @@ string ExternalValueBase::coerceToString(const Pos & pos, PathSet & context, boo
 {
     throw TypeError({
         .hint = hintfmt("cannot coerce %1% to a string", showType()),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 87bb42c11..8986952e3 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -253,7 +253,7 @@ private:
     friend struct ExprAttrs;
     friend struct ExprLet;
 
-    Expr * parse(const char * text, const Path & path,
+    Expr * parse(const char * text, FileOrigin origin, const Path & path,
         const Path & basePath, StaticEnv & staticEnv);
 
 public:
diff --git a/src/libexpr/flake/flake.cc b/src/libexpr/flake/flake.cc
index 871af07b0..fd168b74f 100644
--- a/src/libexpr/flake/flake.cc
+++ b/src/libexpr/flake/flake.cc
@@ -123,7 +123,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
                         attr.name, showType(*attr.value));
             }
         } catch (Error & e) {
-            e.addPrefix(fmt("in flake attribute '%s' at '%s':\n", attr.name, *attr.pos));
+            e.addTrace(*attr.pos, hintfmt("in flake attribute '%s'", attr.name));
             throw;
         }
     }
@@ -132,7 +132,7 @@ static FlakeInput parseFlakeInput(EvalState & state,
         try {
             input.ref = FlakeRef::fromAttrs(attrs);
         } catch (Error & e) {
-            e.addPrefix(fmt("in flake input at '%s':\n", pos));
+            e.addTrace(pos, hintfmt("in flake input"));
             throw;
         }
     else {
@@ -195,7 +195,7 @@ static Flake getFlake(
     Value vInfo;
     state.evalFile(flakeFile, vInfo, true); // FIXME: symlink attack
 
-    expectType(state, tAttrs, vInfo, Pos(state.symbols.create(flakeFile), 0, 0));
+    expectType(state, tAttrs, vInfo, Pos(foFile, state.symbols.create(flakeFile), 0, 0));
 
     auto sEdition = state.symbols.create("edition"); // FIXME: remove soon
 
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index b4b65883d..d5698011f 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -197,7 +197,22 @@ std::ostream & operator << (std::ostream & str, const Pos & pos)
     if (!pos)
         str << "undefined position";
     else
-        str << (format(ANSI_BOLD "%1%" ANSI_NORMAL ":%2%:%3%") % (string) pos.file % pos.line % pos.column).str();
+    {
+        auto f = format(ANSI_BOLD "%1%" ANSI_NORMAL ":%2%:%3%");
+        switch (pos.origin) {
+            case foFile:
+                f % (string) pos.file;
+                break;
+            case foStdin:
+            case foString:
+                f % "(string)";
+                break;
+            default:
+                throw Error("unhandled Pos origin!");
+        }
+        str << (f % pos.line % pos.column).str();
+    }
+
     return str;
 }
 
@@ -270,7 +285,7 @@ void ExprVar::bindVars(const StaticEnv & env)
     if (withLevel == -1)
         throw UndefinedVarError({
             .hint = hintfmt("undefined variable '%1%'", name),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     fromWith = true;
     this->level = withLevel;
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index ec6fd3190..e4cbc660f 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -24,11 +24,12 @@ MakeError(RestrictedPathError, Error);
 
 struct Pos
 {
+    FileOrigin origin;
     Symbol file;
     unsigned int line, column;
-    Pos() : line(0), column(0) { };
-    Pos(const Symbol & file, unsigned int line, unsigned int column)
-        : file(file), line(line), column(column) { };
+    Pos() : origin(foString), line(0), column(0) { };
+    Pos(FileOrigin origin, const Symbol & file, unsigned int line, unsigned int column)
+        : origin(origin), file(file), line(line), column(column) { };
     operator bool() const
     {
         return line != 0;
@@ -238,7 +239,7 @@ struct ExprLambda : Expr
         if (!arg.empty() && formals && formals->argNames.find(arg) != formals->argNames.end())
             throw ParseError({
                 .hint = hintfmt("duplicate formal function argument '%1%'", arg),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
     };
     void setName(Symbol & name);
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 7b28b8509..24b21f7da 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -30,7 +30,8 @@ namespace nix {
         SymbolTable & symbols;
         Expr * result;
         Path basePath;
-        Symbol path;
+        Symbol file;
+        FileOrigin origin;
         ErrorInfo error;
         Symbol sLetBody;
         ParseData(EvalState & state)
@@ -65,18 +66,17 @@ namespace nix {
 static void dupAttr(const AttrPath & attrPath, const Pos & pos, const Pos & prevPos)
 {
     throw ParseError({
-        .hint = hintfmt("attribute '%1%' already defined at %2%",
+         .hint = hintfmt("attribute '%1%' already defined at %2%",
             showAttrPath(attrPath), prevPos),
-        .nixCode = NixCode { .errPos = pos },
+         .errPos = pos
     });
 }
 
-
 static void dupAttr(Symbol attr, const Pos & pos, const Pos & prevPos)
 {
     throw ParseError({
         .hint = hintfmt("attribute '%1%' already defined at %2%", attr, prevPos),
-        .nixCode = NixCode { .errPos = pos },
+        .errPos = pos
     });
 }
 
@@ -148,7 +148,7 @@ static void addFormal(const Pos & pos, Formals * formals, const Formal & formal)
         throw ParseError({
             .hint = hintfmt("duplicate formal function argument '%1%'",
                 formal.name),
-            .nixCode = NixCode { .errPos = pos },
+            .errPos = pos
         });
     formals->formals.push_front(formal);
 }
@@ -246,7 +246,7 @@ static Expr * stripIndentation(const Pos & pos, SymbolTable & symbols, vector<Ex
 
 static inline Pos makeCurPos(const YYLTYPE & loc, ParseData * data)
 {
-    return Pos(data->path, loc.first_line, loc.first_column);
+    return Pos(data->origin, data->file, loc.first_line, loc.first_column);
 }
 
 #define CUR_POS makeCurPos(*yylocp, data)
@@ -259,7 +259,7 @@ void yyerror(YYLTYPE * loc, yyscan_t scanner, ParseData * data, const char * err
 {
     data->error = {
         .hint = hintfmt(error),
-        .nixCode = NixCode { .errPos = makeCurPos(*loc, data) }
+        .errPos = makeCurPos(*loc, data)
     };
 }
 
@@ -339,7 +339,7 @@ expr_function
     { if (!$2->dynamicAttrs.empty())
         throw ParseError({
             .hint = hintfmt("dynamic attributes not allowed in let"),
-            .nixCode = NixCode { .errPos = CUR_POS },
+            .errPos = CUR_POS
         });
       $$ = new ExprLet($2, $4);
     }
@@ -419,7 +419,7 @@ expr_simple
       if (noURLLiterals)
           throw ParseError({
               .hint = hintfmt("URL literals are disabled"),
-              .nixCode = NixCode { .errPos = CUR_POS }
+              .errPos = CUR_POS
           });
       $$ = new ExprString(data->symbols.create($1));
   }
@@ -492,7 +492,7 @@ attrs
       } else
           throw ParseError({
               .hint = hintfmt("dynamic attributes not allowed in inherit"),
-              .nixCode = NixCode { .errPos = makeCurPos(@2, data) },
+              .errPos = makeCurPos(@2, data)
           });
     }
   | { $$ = new AttrPath; }
@@ -569,13 +569,24 @@ formal
 namespace nix {
 
 
-Expr * EvalState::parse(const char * text,
+Expr * EvalState::parse(const char * text, FileOrigin origin,
     const Path & path, const Path & basePath, StaticEnv & staticEnv)
 {
     yyscan_t scanner;
     ParseData data(*this);
+    data.origin = origin;
+    switch (origin) {
+        case foFile: 
+            data.file = data.symbols.create(path);
+            break;
+        case foStdin:
+        case foString:
+            data.file = data.symbols.create(text);
+            break;
+        default:
+            assert(false);
+    }
     data.basePath = basePath;
-    data.path = data.symbols.create(path);
 
     yylex_init(&scanner);
     yy_scan_string(text, scanner);
@@ -625,13 +636,13 @@ Expr * EvalState::parseExprFromFile(const Path & path)
 
 Expr * EvalState::parseExprFromFile(const Path & path, StaticEnv & staticEnv)
 {
-    return parse(readFile(path).c_str(), path, dirOf(path), staticEnv);
+    return parse(readFile(path).c_str(), foFile, path, dirOf(path), staticEnv);
 }
 
 
 Expr * EvalState::parseExprFromString(std::string_view s, const Path & basePath, StaticEnv & staticEnv)
 {
-    return parse(s.data(), "(string)", basePath, staticEnv);
+    return parse(s.data(), foString, "", basePath, staticEnv);
 }
 
 
@@ -644,7 +655,7 @@ Expr * EvalState::parseExprFromString(std::string_view s, const Path & basePath)
 Expr * EvalState::parseStdin()
 {
     //Activity act(*logger, lvlTalkative, format("parsing standard input"));
-    return parseExprFromString(drainFD(0), absPath("."));
+    return parse(drainFD(0).data(), foStdin, "", absPath("."), staticBaseEnv);
 }
 
 
@@ -693,7 +704,7 @@ Path EvalState::findFile(SearchPath & searchPath, const string & path, const Pos
             ? "cannot look up '<%s>' in pure evaluation mode (use '--impure' to override)"
             : "file '%s' was not found in the Nix search path (add it using $NIX_PATH or -I)",
             path),
-        .nixCode = NixCode { .errPos = pos }
+        .errPos = pos
     });
 }
 
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index 96c20b227..539a13f30 100644
--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -84,7 +84,7 @@ static void prim_scopedImport(EvalState & state, const Pos & pos, Value * * args
     } catch (InvalidPathError & e) {
         throw EvalError({
             .hint = hintfmt("cannot import '%1%', since path '%2%' is not valid", path, e.path),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     }
 
@@ -165,7 +165,7 @@ void prim_importNative(EvalState & state, const Pos & pos, Value * * args, Value
             .hint = hintfmt(
                 "cannot import '%1%', since path '%2%' is not valid",
                 path, e.path),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     }
 
@@ -203,7 +203,7 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
     if (count == 0) {
         throw EvalError({
             .hint = hintfmt("at least one argument to 'exec' required"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     }
     PathSet context;
@@ -218,7 +218,7 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
         throw EvalError({
             .hint = hintfmt("cannot execute '%1%', since path '%2%' is not valid",
                 program, e.path),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     }
 
@@ -227,13 +227,13 @@ void prim_exec(EvalState & state, const Pos & pos, Value * * args, Value & v)
     try {
         parsed = state.parseExprFromString(output, pos.file);
     } catch (Error & e) {
-        e.addPrefix(fmt("While parsing the output from '%1%', at %2%\n", program, pos));
+        e.addTrace(pos, "While parsing the output from '%1%'", program);
         throw;
     }
     try {
         state.eval(parsed, v);
     } catch (Error & e) {
-        e.addPrefix(fmt("While evaluating the output from '%1%', at %2%\n", program, pos));
+        e.addTrace(pos, "While evaluating the output from '%1%'", program);
         throw;
     }
 }
@@ -373,7 +373,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     if (startSet == args[0]->attrs->end())
         throw EvalError({
             .hint = hintfmt("attribute 'startSet' required"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     state.forceList(*startSet->value, pos);
 
@@ -387,7 +387,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
     if (op == args[0]->attrs->end())
         throw EvalError({
             .hint = hintfmt("attribute 'operator' required"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     state.forceValue(*op->value, pos);
 
@@ -409,7 +409,7 @@ static void prim_genericClosure(EvalState & state, const Pos & pos, Value * * ar
         if (key == e->attrs->end())
             throw EvalError({
                 .hint = hintfmt("attribute 'key' required"),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
         state.forceValue(*key->value, pos);
 
@@ -459,7 +459,7 @@ static void prim_addErrorContext(EvalState & state, const Pos & pos, Value * * a
         v = *args[1];
     } catch (Error & e) {
         PathSet context;
-        e.addPrefix(format("%1%\n") % state.coerceToString(pos, *args[0], context));
+        e.addTrace(std::nullopt, state.coerceToString(pos, *args[0], context));
         throw;
     }
 }
@@ -544,14 +544,14 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     if (attr == args[0]->attrs->end())
         throw EvalError({
             .hint = hintfmt("required attribute 'name' missing"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     string drvName;
     Pos & posDrvName(*attr->pos);
     try {
         drvName = state.forceStringNoCtx(*attr->value, pos);
     } catch (Error & e) {
-        e.addPrefix(fmt("while evaluating the derivation attribute 'name' at %1%:\n", posDrvName));
+        e.addTrace(posDrvName, "while evaluating the derivation attribute 'name'");
         throw;
     }
 
@@ -591,7 +591,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             else
                 throw EvalError({
                     .hint = hintfmt("invalid value '%s' for 'outputHashMode' attribute", s),
-                    .nixCode = NixCode { .errPos = posDrvName }
+                    .errPos = posDrvName
                 });
         };
 
@@ -601,7 +601,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                 if (outputs.find(j) != outputs.end())
                     throw EvalError({
                         .hint = hintfmt("duplicate derivation output '%1%'", j),
-                        .nixCode = NixCode { .errPos = posDrvName }
+                        .errPos = posDrvName
                     });
                 /* !!! Check whether j is a valid attribute
                    name. */
@@ -611,14 +611,14 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
                 if (j == "drv")
                     throw EvalError({
                         .hint = hintfmt("invalid derivation output name 'drv'" ),
-                        .nixCode = NixCode { .errPos = posDrvName }
+                        .errPos = posDrvName
                     });
                 outputs.insert(j);
             }
             if (outputs.empty())
                 throw EvalError({
                     .hint = hintfmt("derivation cannot have an empty set of outputs"),
-                    .nixCode = NixCode { .errPos = posDrvName }
+                    .errPos = posDrvName
                 });
         };
 
@@ -684,8 +684,9 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
             }
 
         } catch (Error & e) {
-            e.addPrefix(format("while evaluating the attribute '%1%' of the derivation '%2%' at %3%:\n")
-                % key % drvName % posDrvName);
+            e.addTrace(posDrvName, 
+                "while evaluating the attribute '%1%' of the derivation '%2%'",
+                key, drvName);
             throw;
         }
     }
@@ -733,20 +734,20 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
     if (drv.builder == "")
         throw EvalError({
             .hint = hintfmt("required attribute 'builder' missing"),
-            .nixCode = NixCode { .errPos = posDrvName }
+            .errPos = posDrvName
         });
 
     if (drv.platform == "")
         throw EvalError({
             .hint = hintfmt("required attribute 'system' missing"),
-            .nixCode = NixCode { .errPos = posDrvName }
+            .errPos = posDrvName
         });
 
     /* Check whether the derivation name is valid. */
     if (isDerivation(drvName))
         throw EvalError({
             .hint = hintfmt("derivation names are not allowed to end in '%s'", drvExtension),
-            .nixCode = NixCode { .errPos = posDrvName }
+            .errPos = posDrvName
         });
 
     if (outputHash) {
@@ -754,7 +755,7 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
         if (outputs.size() != 1 || *(outputs.begin()) != "out")
             throw Error({
                 .hint = hintfmt("multiple outputs are not supported in fixed-output derivations"),
-                .nixCode = NixCode { .errPos = posDrvName }
+                .errPos = posDrvName
             });
 
         std::optional<HashType> ht = parseHashTypeOpt(outputHashAlgo);
@@ -868,7 +869,7 @@ static void prim_storePath(EvalState & state, const Pos & pos, Value * * args, V
     if (!state.store->isInStore(path))
         throw EvalError({
             .hint = hintfmt("path '%1%' is not in the Nix store", path),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     Path path2 = state.store->toStorePath(path);
     if (!settings.readOnlyMode)
@@ -889,7 +890,7 @@ static void prim_pathExists(EvalState & state, const Pos & pos, Value * * args,
             .hint = hintfmt(
                 "cannot check the existence of '%1%', since path '%2%' is not valid",
                 path, e.path),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     }
 
@@ -935,7 +936,7 @@ static void prim_readFile(EvalState & state, const Pos & pos, Value * * args, Va
     } catch (InvalidPathError & e) {
         throw EvalError({
             .hint = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     }
     string s = readFile(state.checkSourcePath(state.toRealPath(path, context)));
@@ -966,7 +967,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         if (i == v2.attrs->end())
             throw EvalError({
                 .hint = hintfmt("attribute 'path' missing"),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
 
         PathSet context;
@@ -977,7 +978,7 @@ static void prim_findFile(EvalState & state, const Pos & pos, Value * * args, Va
         } catch (InvalidPathError & e) {
             throw EvalError({
                 .hint = hintfmt("cannot find '%1%', since path '%2%' is not valid", path, e.path),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
         }
 
@@ -997,7 +998,7 @@ static void prim_hashFile(EvalState & state, const Pos & pos, Value * * args, Va
     if (!ht)
       throw Error({
           .hint = hintfmt("unknown hash type '%1%'", type),
-          .nixCode = NixCode { .errPos = pos }
+          .errPos = pos
       });
 
     PathSet context; // discarded
@@ -1016,7 +1017,7 @@ static void prim_readDir(EvalState & state, const Pos & pos, Value * * args, Val
     } catch (InvalidPathError & e) {
         throw EvalError({
             .hint = hintfmt("cannot read '%1%', since path '%2%' is not valid", path, e.path),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     }
 
@@ -1092,7 +1093,7 @@ static void prim_toFile(EvalState & state, const Pos & pos, Value * * args, Valu
                     "in 'toFile': the file named '%1%' must not contain a reference "
                     "to a derivation but contains (%2%)",
                     name, path),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
         refs.insert(state.store->parseStorePath(path));
     }
@@ -1163,7 +1164,7 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
     if (!context.empty())
         throw EvalError({
             .hint = hintfmt("string '%1%' cannot refer to other paths", path),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
 
     state.forceValue(*args[0], pos);
@@ -1172,7 +1173,7 @@ static void prim_filterSource(EvalState & state, const Pos & pos, Value * * args
             .hint = hintfmt(
                 "first argument in call to 'filterSource' is not a function but %1%",
                 showType(*args[0])),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
 
     addPath(state, pos, std::string(baseNameOf(path)), path, args[0], FileIngestionMethod::Recursive, Hash(), v);
@@ -1195,7 +1196,7 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
             if (!context.empty())
                 throw EvalError({
                     .hint = hintfmt("string '%1%' cannot refer to other paths", path),
-                    .nixCode = NixCode { .errPos = *attr.pos }
+                    .errPos = *attr.pos
                 });
         } else if (attr.name == state.sName)
             name = state.forceStringNoCtx(*attr.value, *attr.pos);
@@ -1209,13 +1210,13 @@ static void prim_path(EvalState & state, const Pos & pos, Value * * args, Value
         else
             throw EvalError({
                 .hint = hintfmt("unsupported argument '%1%' to 'addPath'", attr.name),
-                .nixCode = NixCode { .errPos = *attr.pos }
+                .errPos = *attr.pos
             });
     }
     if (path.empty())
         throw EvalError({
             .hint = hintfmt("'path' required"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     if (name.empty())
         name = baseNameOf(path);
@@ -1276,7 +1277,7 @@ void prim_getAttr(EvalState & state, const Pos & pos, Value * * args, Value & v)
     if (i == args[1]->attrs->end())
         throw EvalError({
             .hint = hintfmt("attribute '%1%' missing", attr),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     // !!! add to stack trace?
     if (state.countCalls && i->pos) state.attrSelects[*i->pos]++;
@@ -1359,7 +1360,7 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
         if (j == v2.attrs->end())
             throw TypeError({
                 .hint = hintfmt("'name' attribute missing in a call to 'listToAttrs'"),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
         string name = state.forceStringNoCtx(*j->value, pos);
 
@@ -1369,7 +1370,7 @@ static void prim_listToAttrs(EvalState & state, const Pos & pos, Value * * args,
             if (j2 == v2.attrs->end())
                 throw TypeError({
                     .hint = hintfmt("'value' attribute missing in a call to 'listToAttrs'"),
-                    .nixCode = NixCode { .errPos = pos }
+                    .errPos = pos
                 });
             v.attrs->push_back(Attr(sym, j2->value, j2->pos));
         }
@@ -1445,7 +1446,7 @@ static void prim_functionArgs(EvalState & state, const Pos & pos, Value * * args
     if (args[0]->type != tLambda)
         throw TypeError({
             .hint = hintfmt("'functionArgs' requires a function"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
 
     if (!args[0]->lambda.fun->matchAttrs) {
@@ -1501,7 +1502,7 @@ static void elemAt(EvalState & state, const Pos & pos, Value & list, int n, Valu
     if (n < 0 || (unsigned int) n >= list.listSize())
         throw Error({
             .hint = hintfmt("list index %1% is out of bounds", n),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
     state.forceValue(*list.listElems()[n], pos);
     v = *list.listElems()[n];
@@ -1531,7 +1532,7 @@ static void prim_tail(EvalState & state, const Pos & pos, Value * * args, Value
     if (args[0]->listSize() == 0)
         throw Error({
             .hint = hintfmt("'tail' called on an empty list"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
 
     state.mkList(v, args[0]->listSize() - 1);
@@ -1676,7 +1677,7 @@ static void prim_genList(EvalState & state, const Pos & pos, Value * * args, Val
     if (len < 0)
         throw EvalError({
             .hint = hintfmt("cannot create list of size %1%", len),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
 
     state.mkList(v, len);
@@ -1838,7 +1839,7 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
     if (f2 == 0)
         throw EvalError({
             .hint = hintfmt("division by zero"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
 
     if (args[0]->type == tFloat || args[1]->type == tFloat) {
@@ -1850,7 +1851,7 @@ static void prim_div(EvalState & state, const Pos & pos, Value * * args, Value &
         if (i1 == std::numeric_limits<NixInt>::min() && i2 == -1)
             throw EvalError({
                 .hint = hintfmt("overflow in integer division"),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
 
         mkInt(v, i1 / i2);
@@ -1911,7 +1912,7 @@ static void prim_substring(EvalState & state, const Pos & pos, Value * * args, V
     if (start < 0)
         throw EvalError({
             .hint = hintfmt("negative start position in 'substring'"),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
 
     mkString(v, (unsigned int) start >= s.size() ? "" : string(s, start, len), context);
@@ -1934,7 +1935,7 @@ static void prim_hashString(EvalState & state, const Pos & pos, Value * * args,
     if (!ht)
         throw Error({
             .hint = hintfmt("unknown hash type '%1%'", type),
-            .nixCode = NixCode { .errPos = pos }
+            .errPos = pos
         });
 
     PathSet context; // discarded
@@ -1980,12 +1981,12 @@ void prim_match(EvalState & state, const Pos & pos, Value * * args, Value & v)
             // limit is _GLIBCXX_REGEX_STATE_LIMIT for libstdc++
             throw EvalError({
                 .hint = hintfmt("memory limit exceeded by regular expression '%s'", re),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
         } else {
             throw EvalError({
                 .hint = hintfmt("invalid regular expression '%s'", re),
-                .nixCode = NixCode { .errPos = pos }
+                .errPos = pos
             });
         }