fix: builtins using the incorrect data to type conversion when used as a function param.

CHANGELOG.md

@@ -22,6 +22,7 @@
 - **aiken-lang**: Fix for tuple clause not consuming the next case causing
   incomplete contracts. Now tuple clause will always consume the next case
   unless it is the final clause
+  - **aiken-lang**: Fix for builtins using the incorrect data to type conversion when used as a function param.
 
 ## v1.0.10-alpha - 2023-06-13
 

crates/aiken-lang/src/gen_uplc.rs

@@ -4168,6 +4168,11 @@ impl<'a> CodeGenerator<'a> {
                     arg_vec.push(arg_stack.pop().unwrap());
                 }
 
+                let tipo = match tipo.as_ref() {
+                    Type::Fn { ret, .. } => ret,
+                    _ => &tipo,
+                };
+
                 let term = match &func {
                     DefaultFunction::IfThenElse
                     | DefaultFunction::ChooseUnit
@@ -4181,11 +4186,11 @@ impl<'a> CodeGenerator<'a> {
                     DefaultFunction::FstPair
                     | DefaultFunction::SndPair
                     | DefaultFunction::HeadList => {
-                        builder::undata_builtin(&func, count, &tipo, arg_vec)
+                        builder::undata_builtin(&func, count, tipo, arg_vec)
                     }
 
                     DefaultFunction::MkCons | DefaultFunction::MkPairData => {
-                        builder::to_data_builtin(&func, count, &tipo, arg_vec)
+                        builder::to_data_builtin(&func, count, tipo, arg_vec)
                     }
                     _ => {
                         let mut term: Term<Name> = func.into();

examples/acceptance_tests/084/lib/tests.ak

@@ -1,3 +1,5 @@
+use aiken/builtin.{snd_pair}
+use aiken/cbor
 use aiken/list
 
 test tuple_when() {
@@ -20,3 +22,8 @@ test tuple_when() {
     )
   list.length(filtered) > 0
 }
+
+test t() {
+  trace cbor.diagnostic(list.map([(#"", 20)], snd_pair))
+  True
+}