Fix plumbing

compiler/builtins/bitcode/src/list.zig

@@ -722,6 +722,16 @@ pub fn listAppend(list: RocList, alignment: u32, element: Opaque, element_width:
     return output;
 }
 
+pub fn listSwap(
+    list: RocList,
+    alignment: u32,
+    element_width: usize,
+    index_1: usize,
+    index_2: usize,
+) callconv(.C) RocList {
+    return RocList.empty();
+}
+
 pub fn listDrop(
     list: RocList,
     alignment: u32,

compiler/can/src/builtins.rs

@@ -1885,13 +1885,13 @@ fn list_set(symbol: Symbol, var_store: &mut VarStore) -> Def {
 }
 
 /// List.swap : List elem, Nat, Nat -> List elem
-fn list_drop(symbol: Symbol, var_store: &mut VarStore) -> Def {
+fn list_swap(symbol: Symbol, var_store: &mut VarStore) -> Def {
     let list_var = var_store.fresh();
     let index1_var = var_store.fresh();
     let index2_var = var_store.fresh();
 
     let body = RunLowLevel {
-        op: LowLevel::ListDrop,
+        op: LowLevel::ListSwap,
         args: vec![
             (list_var, Var(Symbol::ARG_1)),
             (index1_var, Var(Symbol::ARG_2)),

compiler/gen/src/llvm/build.rs

@@ -4171,15 +4171,16 @@ fn run_low_level<'a, 'ctx, 'env>(
             let (list, list_layout) = load_symbol_and_layout(scope, &args[0]);
             let original_wrapper = list.into_struct_value();
 
-            let count = load_symbol(scope, &args[1]);
+            let index_1 = load_symbol(scope, &args[1]);
+            let index_2 = load_symbol(scope, &args[2]);
 
             match list_layout {
                 Layout::Builtin(Builtin::EmptyList) => empty_list(env),
                 Layout::Builtin(Builtin::List(element_layout)) => list_swap(
                     env,
-                    layout_ids,
                     original_wrapper,
-                    count.into_int_value(),
+                    index_1.into_int_value(),
+                    index_2.into_int_value(),
                     element_layout,
                 ),
                 _ => unreachable!("Invalid layout {:?} in List.swap", list_layout),

compiler/gen/src/llvm/build_list.rs

@@ -307,19 +307,19 @@ pub fn list_append<'a, 'ctx, 'env>(
 /// List.swap : List elem, Nat, Nat -> List elem
 pub fn list_swap<'a, 'ctx, 'env>(
     env: &Env<'a, 'ctx, 'env>,
-    layout_ids: &mut LayoutIds<'a>,
     original_wrapper: StructValue<'ctx>,
-    count: IntValue<'ctx>,
+    index_1: IntValue<'ctx>,
+    index_2: IntValue<'ctx>,
     element_layout: &Layout<'a>,
 ) -> BasicValueEnum<'ctx> {
-    let dec_element_fn = build_dec_wrapper(env, layout_ids, &element_layout);
     call_bitcode_fn_returns_list(
         env,
         &[
             pass_list_as_i128(env, original_wrapper.into()),
             env.alignment_intvalue(&element_layout),
             layout_width(env, &element_layout),
-            count.into(),
+            index_1.into(),
+            index_2.into(),
         ],
         &bitcode::LIST_SWAP,
     )

compiler/module/src/low_level.rs

@@ -40,6 +40,7 @@ pub enum LowLevel {
     ListKeepErrs,
     ListSortWith,
     ListDrop,
+    ListSwap,
     DictSize,
     DictEmpty,
     DictInsert,

compiler/test_gen/src/gen_list.rs

@@ -181,11 +181,7 @@ fn list_drop() {
 
 #[test]
 fn list_swap() {
-    assert_evals_to!(
+    assert_evals_to!("List.swap [] 0 1", RocList::from_slice(&[]), RocList<i64>);
-        "List.swap [] 0 1",
-        RocList::from_slice(&[]),
-        RocList<i64>
-    );
     assert_evals_to!(
         "List.swap [ 0 ] 1 2",
         RocList::from_slice(&[0]),