From 4adf6f27ad394b8a48f5565be7dfb26a9c26ce5a Mon Sep 17 00:00:00 2001
From: Pi Lanningham <pi@sundaeswap.finance>
Date: Mon, 17 Feb 2025 15:55:33 -0500
Subject: [PATCH] Avoid wiping out traces when accessing logs

The clones are cheap enough here that we likely don't need to worry about the cost of cloning; and this removes a significant foot-gun where you can wipe out the logs/labels by accessing the other field.
---
 crates/aiken-lang/src/test_framework.rs |  8 ++++----
 crates/aiken/src/cmd/uplc/eval.rs       |  2 +-
 crates/uplc/src/machine/eval_result.rs  | 18 ++++++++++--------
 crates/uplc/src/tx/eval.rs              |  2 +-
 4 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/crates/aiken-lang/src/test_framework.rs b/crates/aiken-lang/src/test_framework.rs
index ab23ec0a..295dee81 100644
--- a/crates/aiken-lang/src/test_framework.rs
+++ b/crates/aiken-lang/src/test_framework.rs
@@ -222,7 +222,7 @@ unsafe impl Send for UnitTest {}
 
 impl UnitTest {
     pub fn run(self, plutus_version: &PlutusVersion) -> UnitTestResult<(Constant, Rc<Type>)> {
-        let mut eval_result = Program::<NamedDeBruijn>::try_from(self.program.clone())
+        let eval_result = Program::<NamedDeBruijn>::try_from(self.program.clone())
             .unwrap()
             .eval_version(ExBudget::max(), &plutus_version.into());
 
@@ -384,7 +384,7 @@ impl PropertyTest {
             .sample(&self.fuzzer.program)?
             .expect("A seeded PRNG returned 'None' which indicates a fuzzer is ill-formed and implemented wrongly; please contact library's authors.");
 
-        let mut result = self.eval(&value, plutus_version);
+        let result = self.eval(&value, plutus_version);
 
         for label in result.labels() {
             // NOTE: There may be other log outputs that interefere with labels. So *by
@@ -536,7 +536,7 @@ impl Benchmark {
 
                 Ok(Some((new_prng, value))) => {
                     prng = new_prng;
-                    let mut result = self.eval(&value, plutus_version);
+                    let result = self.eval(&value, plutus_version);
                     match result.result() {
                         Ok(_) => measures.push((size, result.cost())),
                         Err(uplc_error) => {
@@ -664,7 +664,7 @@ impl Prng {
         fuzzer: &Program<Name>,
     ) -> Result<Option<(Prng, PlutusData)>, FuzzerError> {
         let program = Program::<NamedDeBruijn>::try_from(fuzzer.apply_data(self.uplc())).unwrap();
-        let mut result = program.eval(ExBudget::max());
+        let result = program.eval(ExBudget::max());
         result
             .result()
             .map_err(|uplc_error| FuzzerError {
diff --git a/crates/aiken/src/cmd/uplc/eval.rs b/crates/aiken/src/cmd/uplc/eval.rs
index b59fec23..61f4a81f 100644
--- a/crates/aiken/src/cmd/uplc/eval.rs
+++ b/crates/aiken/src/cmd/uplc/eval.rs
@@ -77,7 +77,7 @@ pub fn exec(
 
     let program = Program::<NamedDeBruijn>::try_from(program).into_diagnostic()?;
 
-    let mut eval_result = if debug {
+    let eval_result = if debug {
         program.eval_debug(ExBudget::default(), &Language::PlutusV3)
     } else {
         program.eval(budget)
diff --git a/crates/uplc/src/machine/eval_result.rs b/crates/uplc/src/machine/eval_result.rs
index 9fbddceb..b6679e4b 100644
--- a/crates/uplc/src/machine/eval_result.rs
+++ b/crates/uplc/src/machine/eval_result.rs
@@ -31,20 +31,22 @@ impl EvalResult {
         self.initial_budget - self.remaining_budget
     }
 
-    pub fn traces(&mut self) -> Vec<Trace> {
-        std::mem::take(&mut self.traces)
+    pub fn traces(&self) -> Vec<Trace> {
+        self.traces.clone()
     }
 
-    pub fn logs(&mut self) -> Vec<String> {
-        std::mem::take(&mut self.traces)
-            .into_iter()
+    pub fn logs(&self) -> Vec<String> {
+        self.traces
+            .iter()
+            .cloned()
             .filter_map(Trace::unwrap_log)
             .collect()
     }
 
-    pub fn labels(&mut self) -> Vec<String> {
-        std::mem::take(&mut self.traces)
-            .into_iter()
+    pub fn labels(&self) -> Vec<String> {
+        self.traces
+            .iter()
+            .cloned()
             .filter_map(Trace::unwrap_label)
             .collect()
     }
diff --git a/crates/uplc/src/tx/eval.rs b/crates/uplc/src/tx/eval.rs
index b1259d9c..25f3a4f7 100644
--- a/crates/uplc/src/tx/eval.rs
+++ b/crates/uplc/src/tx/eval.rs
@@ -49,7 +49,7 @@ pub fn eval_redeemer(
             ScriptContext::V3 { .. } => program.apply_data(script_context.to_plutus_data()),
         };
 
-        let mut eval_result = if let Some(costs) = cost_mdl_opt {
+        let eval_result = if let Some(costs) = cost_mdl_opt {
             program.eval_as(lang, costs, Some(initial_budget))
         } else {
             program.eval_version(ExBudget::default(), lang)