chore: Failure == Any

Author: mtshiba

crates/erg_compiler/context/compare.rs

@@ -166,9 +166,9 @@ impl Context {
             return (Absolutely, true);
         }
         match (lhs, rhs) {
-            (Obj, _) | (_, Never | Failure) => (Absolutely, true),
+            (Obj | Failure, _) | (_, Never | Failure) => (Absolutely, true),
             (_, Obj) if lhs.is_mono_value_class() => (Absolutely, false),
-            (Never | Failure, _) if rhs.is_mono_value_class() => (Absolutely, false),
+            (Never, _) if rhs.is_mono_value_class() => (Absolutely, false),
             (Complex | Float | Ratio | Int | Nat | Bool, Bool)
             | (Complex | Float | Ratio | Int | Nat, Nat)
             | (Complex | Float | Ratio | Int, Int)

crates/erg_compiler/context/generalize.rs

@@ -683,9 +683,6 @@ impl<'c, 'q, 'l, L: Locational> Dereferencer<'c, 'q, 'l, L> {
                     args: new_args,
                 })
             }
-            TyParam::Failure if self.level == 0 => Err(TyCheckErrors::from(
-                TyCheckError::dummy_infer_error(self.ctx.cfg.input.clone(), fn_name!(), line!()),
-            )),
             TyParam::Mono(_) | TyParam::Failure => Ok(tp),
         }
     }

crates/erg_compiler/context/instantiate_spec.rs

@@ -594,14 +594,16 @@ impl Context {
                         .get_singular_ctxs(&attr.obj.clone().downgrade(), self)
                         .map_err(|errs| (Type::Failure, errs.into()))?;
                     for ctx in ctxs {
-                        if let Ok(typ) = ctx.instantiate_local_poly_t(
+                        match ctx.instantiate_local_poly_t(
                             &attr.name,
                             &poly.args,
                             opt_decl_t,
                             tmp_tv_cache,
                             not_found_is_qvar,
                         ) {
-                            return Ok(typ);
+                            Ok(typ) => return Ok(typ),
+                            Err((Type::Failure, _)) => {}
+                            Err((typ, es)) => return Err((typ, es)),
                         }
                     }
                     Err((

crates/erg_compiler/ty/mod.rs

@@ -1391,7 +1391,8 @@ pub enum Type {
     },
     FreeVar(FreeTyVar), // a reference to the type of other expression, see docs/compiler/inference.md
     #[default]
-    Failure, // indicates a failure of type inference and behaves as `Never`.
+    /// for all T, `T <: Failure and T :> Failure`
+    Failure, // indicates a failure of type inference and behaves as `Any`.
     /// used to represent `TyParam` is not initialized (see `erg_compiler::context::instantiate_tp`)
     Uninited,
 }