internal/rosa/azalea: record position in func expr

This is included in the evaluation error message.

Signed-off-by: Ophestra <cat@gensokyo.uk>

1 files changed, 20 insertions, 2 deletions

diff --git a/internal/rosa/azalea/evaluate.go b/internal/rosa/azalea/evaluate.go
index 9b119100..85e20583 100644
--- a/internal/rosa/azalea/evaluate.go
+++ b/internal/rosa/azalea/evaluate.go
@@ -211,6 +211,18 @@ func exprTextIndent(expr any) string {
 	return strings.ReplaceAll(ExprText(expr), "\n", "\n\t")
 }
 
+// posString returns the string representation of the position of expr, if
+// available. Otherwise, it returns a hardcoded string.
+func posString(expr any) string {
+	switch v := expr.(type) {
+	case Func:
+		return v.Pos.String()
+
+	default:
+		return "<unknown>"
+	}
+}
+
 // EvaluationError is an error and the expression it occurred in.
 type EvaluationError struct {
 	Expr any
@@ -225,10 +237,16 @@ func (e EvaluationError) Unwrap() error { return e.Err }
 func (e EvaluationError) Error() string {
 	v, ok := errors.AsType[EvaluationError](e.Err)
 	if ok {
-		return fmt.Sprintf("%v\n%s", v, ExprText(e.Expr))
+		return fmt.Sprintf(
+			"%v\n%s\n\t%s",
+			v, ExprText(e.Expr), posString(e.Expr),
+		)
 	}
 
-	return fmt.Sprintf("%v\n\n%s", e.Err, ExprText(e.Expr))
+	return fmt.Sprintf(
+		"%v\n\n%s\n\t%s",
+		e.Err, ExprText(e.Expr), posString(e.Expr),
+	)
 }
 
 var (