Merge pull request #4240 from bburdette/2259-error-message

2259 error message - "auto-call" error

src/libexpr/eval.cc

@@ -657,11 +657,6 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s))
  });
 }
 
-LocalNoInlineNoReturn(void throwTypeError(const char * s, const string & s1))
-{
- throw TypeError(s, s1);
-}
-
 LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const ExprLambda & fun, const Symbol & s2))
 {
  throw TypeError({
@@ -686,6 +681,14 @@ LocalNoInlineNoReturn(void throwUndefinedVarError(const Pos & pos, const char *
  });
 }
 
+LocalNoInlineNoReturn(void throwMissingArgumentError(const Pos & pos, const char * s, const string & s1))
+{
+ throw MissingArgumentError({
+ .hint = hintfmt(s, s1),
+ .errPos = pos
+ });
+}
+
 LocalNoInline(void addErrorTrace(Error & e, const char * s, const string & s2))
 {
  e.addTrace(std::nullopt, s, s2);
@@ -1376,7 +1379,13 @@ void EvalState::autoCallFunction(Bindings & args, Value & fun, Value & res)
  if (j != args.end()) {
  actualArgs->attrs->push_back(*j);
  } else if (!i.def) {
- throwTypeError("cannot auto-call a function that has an argument without a default value ('%1%')", i.name);
+ throwMissingArgumentError(i.pos, R"(cannot evaluate a function that has an argument without a value ('%1%')
+
+nix attempted to evaluate a function as a top level expression; in this case it must have its
+arguments supplied either by default values, or passed explicitly with --arg or --argstr.
+
+https://nixos.org/manual/nix/stable/#ss-functions)", i.name);
+
  }
  }
  }

src/libexpr/nixexpr.hh

@@ -17,6 +17,7 @@ MakeError(ThrownError, AssertionError);
 MakeError(Abort, EvalError);
 MakeError(TypeError, EvalError);
 MakeError(UndefinedVarError, Error);
+MakeError(MissingArgumentError, Error);
 MakeError(RestrictedPathError, Error);
 
 

src/libutil/error.hh

@@ -38,7 +38,7 @@ namespace nix {
  ErrorInfo structs are sent to the logger as part of an exception, or directly with the
  logError or logWarning macros.
 
- See the error-demo.cc program for usage examples.
+ See libutil/tests/logging.cc for usage examples.
 
  */