Fix subtyping ordering & some bugs

examples/typechecking/instantiation.an

@@ -17,5 +17,5 @@ id x = x
 // add : (forall a b c d e f g h i. ((a - c => e can g) - (a - b => c can g) -> (a => (b => e can g) can h) can i))
 // id : (forall a b. (a -> a can b))
 // one : (forall a b c d. ((a => b can d) - a -> b can d))
-// two1 : (forall a b c. ((a => a can c) - a -> a can c))
+// two1 : (forall a b c. ((b => b can c) - b -> b can c))
 // two2 : ((a => a can c) => (a => a can c) can d)

src/hir/monomorphisation.rs

@@ -700,8 +700,8 @@ impl<'c> Context<'c> {
         if definition.trait_impl.is_some() {
             let definition_type = definition.typ.as_ref().unwrap().remove_forall();
             let bindings = typechecker::try_unify(
-                definition_type,
                 typ,
+                definition_type,
                 definition.location,
                 &mut self.cache,
                 TE::MonomorphizationError,

src/types/traitchecker.rs

@@ -288,8 +288,8 @@ fn find_matching_normal_impls(
 
             let location = constraint.locate(cache);
             let type_bindings = typechecker::try_unify_all_with_bindings(
-                &impl_typeargs,
                 constraint.args(),
+                &impl_typeargs,
                 bindings.clone(),
                 location,
                 cache,

src/types/typechecker.rs

@@ -66,7 +66,7 @@ type LevelBindings = Vec<(TypeVariableId, LetBindingLevel)>;
 
 /// Arbitrary limit of maximum recursive calls to functions like find_binding.
 /// Expected not to happen but leads to better errors than a stack overflow when it does.
-const RECURSION_LIMIT: u32 = 15;
+const RECURSION_LIMIT: u32 = 100;
 
 #[derive(Debug, Clone)]
 pub struct UnificationBindings {
@@ -716,6 +716,9 @@ pub fn try_unify_with_bindings_inner<'b>(
         // ! <: &
         (Tag(TypeTag::Mutable), Tag(TypeTag::Immutable)) => Ok(()),
 
+        // owned <: shared
+        (Tag(TypeTag::Owned), Tag(TypeTag::Shared)) => Ok(()),
+
         _ => Err(()),
     }
 }