From 20917bbd5b185a3b9202f64001e9695abc5a6b17 Mon Sep 17 00:00:00 2001
From: rvcas <x@rvcas.dev>
Date: Mon, 19 Feb 2024 20:52:38 -0500
Subject: [PATCH] feat(machine): fix Value::Constr fields order

cc @MicroProofs
---
 crates/uplc/src/machine.rs                             | 10 ++++++----
 .../evaluation/term/constr/constr-3/constr-3.uplc      |  4 ++++
 .../term/constr/constr-3/constr-3.uplc.budget.expected |  2 ++
 .../term/constr/constr-3/constr-3.uplc.expected        |  1 +
 4 files changed, 13 insertions(+), 4 deletions(-)
 create mode 100644 crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc
 create mode 100644 crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc.budget.expected
 create mode 100644 crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc.expected

diff --git a/crates/uplc/src/machine.rs b/crates/uplc/src/machine.rs
index 0aa02b2f..dcca572c 100644
--- a/crates/uplc/src/machine.rs
+++ b/crates/uplc/src/machine.rs
@@ -163,8 +163,10 @@ impl Machine {
             Term::Constr { tag, mut fields } => {
                 self.step_and_maybe_spend(StepKind::Constr)?;
 
+                fields.reverse();
+
                 if !fields.is_empty() {
-                    let popped_field = fields.remove(0);
+                    let popped_field = fields.pop().unwrap();
 
                     Ok(MachineState::Compute(
                         Context::FrameConstr(env.clone(), tag, fields, vec![], context.into()),
@@ -213,10 +215,10 @@ impl Machine {
             Context::FrameAwaitArg(fun, ctx) => self.apply_evaluate(*ctx, fun, value),
             Context::FrameAwaitFunValue(arg, ctx) => self.apply_evaluate(*ctx, value, arg),
             Context::FrameConstr(env, tag, mut fields, mut resolved_fields, ctx) => {
-                resolved_fields.insert(0, value);
+                resolved_fields.push(value);
 
                 if !fields.is_empty() {
-                    let popped_field = fields.remove(0);
+                    let popped_field = fields.pop().unwrap();
 
                     Ok(MachineState::Compute(
                         Context::FrameConstr(env.clone(), tag, fields, resolved_fields, ctx),
@@ -376,7 +378,7 @@ fn transfer_arg_stack(mut args: Vec<Value>, ctx: Context) -> Context {
     if args.is_empty() {
         ctx
     } else {
-        let popped_field = args.remove(0);
+        let popped_field = args.pop().unwrap();
 
         transfer_arg_stack(args, Context::FrameAwaitFunValue(popped_field, ctx.into()))
     }
diff --git a/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc b/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc
new file mode 100644
index 00000000..03932fb8
--- /dev/null
+++ b/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc
@@ -0,0 +1,4 @@
+-- constr can have arbitrary terms in it
+(program 1.1.0
+    (constr 1 (con integer 1) (lam x x) (constr 0 (con integer 1)))
+)
diff --git a/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc.budget.expected b/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc.budget.expected
new file mode 100644
index 00000000..71e43512
--- /dev/null
+++ b/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc.budget.expected
@@ -0,0 +1,2 @@
+({cpu: 115100
+| mem: 600})
\ No newline at end of file
diff --git a/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc.expected b/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc.expected
new file mode 100644
index 00000000..eba1d628
--- /dev/null
+++ b/crates/uplc/test_data/conformance/evaluation/term/constr/constr-3/constr-3.uplc.expected
@@ -0,0 +1 @@
+(program 1.1.0 (constr 1 (con integer 1) (lam x x) (constr 0 (con integer 1))))
\ No newline at end of file