From 801660d74afa17b73fd4c03cd66a782693049f95 Mon Sep 17 00:00:00 2001
From: Denys Zadorozhnyi <denys@zadorozhnyi.com>
Date: Fri, 21 Jul 2023 11:27:48 +0300
Subject: [PATCH] enrich Append eval error with source span;

---
 ergotree-interpreter/src/eval.rs      | 19 +++++++++++++++++++
 ergotree-interpreter/src/eval/expr.rs | 13 ++++++++++++-
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/ergotree-interpreter/src/eval.rs b/ergotree-interpreter/src/eval.rs
index 8202cd5c3..1a5ebfcd5 100644
--- a/ergotree-interpreter/src/eval.rs
+++ b/ergotree-interpreter/src/eval.rs
@@ -1,6 +1,7 @@
 //! Interpreter
 use bounded_vec::BoundedVecOutOfBounds;
 use ergotree_ir::mir::constant::TryExtractInto;
+use ergotree_ir::mir::expr::SourceSpan;
 use ergotree_ir::sigma_protocol::sigma_boolean::SigmaProp;
 use sigma_ser::ScorexParsingError;
 use sigma_ser::ScorexSerializationError;
@@ -163,6 +164,24 @@ pub enum EvalError {
         /// environment after evaluation
         env: Env,
     },
+    /// Wrapped eval error with source span
+    #[error("eval error: {error}, source span: {source_span:?}")]
+    WrappedWithSpan {
+        /// eval error
+        error: Box<EvalError>,
+        /// source span
+        source_span: SourceSpan,
+    },
+}
+
+impl EvalError {
+    /// Wrap eval error with source span
+    pub fn wrap_with_span(self, source_span: SourceSpan) -> Self {
+        EvalError::WrappedWithSpan {
+            error: Box::new(self),
+            source_span,
+        }
+    }
 }
 
 /// Result of expression reduction procedure (see `reduce_to_crypto`).
diff --git a/ergotree-interpreter/src/eval/expr.rs b/ergotree-interpreter/src/eval/expr.rs
index 8929c2ed2..8dd436445 100644
--- a/ergotree-interpreter/src/eval/expr.rs
+++ b/ergotree-interpreter/src/eval/expr.rs
@@ -1,4 +1,5 @@
 use ergotree_ir::mir::expr::Expr;
+use ergotree_ir::mir::expr::SourceSpan;
 use ergotree_ir::mir::value::Value;
 
 use super::Env;
@@ -50,7 +51,7 @@ impl Evaluable for Expr {
             Expr::Upcast(op) => op.eval(env, ctx),
             Expr::Downcast(op) => op.eval(env, ctx),
             Expr::If(op) => op.eval(env, ctx),
-            Expr::Append(op) => op.expr().eval(env, ctx),
+            Expr::Append(op) => op.expr().eval(env, ctx).with_span(&op.source_span),
             Expr::ByIndex(op) => op.eval(env, ctx),
             Expr::ExtractScriptBytes(op) => op.eval(env, ctx),
             Expr::SizeOf(op) => op.eval(env, ctx),
@@ -83,3 +84,13 @@ impl Evaluable for Expr {
         }
     }
 }
+
+pub trait ExtResultEvalError<T> {
+    fn with_span(self, span: &SourceSpan) -> Result<T, EvalError>;
+}
+
+impl<T> ExtResultEvalError<T> for Result<T, EvalError> {
+    fn with_span(self, span: &SourceSpan) -> Result<T, EvalError> {
+        self.map_err(|e| e.wrap_with_span(span.clone()))
+    }
+}