Rename visitor + performance

Author: cdce8p

mypy/expandtype.py

@@ -44,7 +44,7 @@
     flatten_nested_unions,
     get_proper_type,
     has_param_specs,
-    has_type_vars_default,
+    has_type_var_like_default,
     remove_trivial,
 )
 from mypy.typevartuples import (
@@ -250,7 +250,7 @@ def visit_type_var(self, t: TypeVarType) -> Type:
             t = t.copy_modified(upper_bound=t.upper_bound.accept(self))
         repl = self.variables.get(t.id, t)
 
-        if has_type_vars_default(repl):
+        if has_type_var_like_default(repl):
             if repl in self.recursive_guard:
                 return repl
             self.recursive_guard.add(repl)

mypy/types.py

@@ -3441,7 +3441,7 @@ def has_type_vars(typ: Type) -> bool:
     return typ.accept(HasTypeVars())
 
 
-class HasTypeVarDefault(BoolTypeQuery):
+class HasTypeVarLikeDefault(BoolTypeQuery):
     def __init__(self) -> None:
         super().__init__(ANY_STRATEGY)
         self.skip_alias_target = True
@@ -3456,8 +3456,13 @@ def visit_param_spec(self, t: ParamSpecType) -> bool:
         return t.has_default()
 
 
-def has_type_vars_default(typ: Type) -> bool:
-    return typ.accept(HasTypeVarDefault())
+# Use singleton since this is hot (note: call reset() before using)
+_has_type_var_like_default: Final = HasTypeVarLikeDefault()
+
+
+def has_type_var_like_default(typ: Type) -> bool:
+    _has_type_var_like_default.reset()
+    return typ.accept(_has_type_var_like_default)
 
 
 class HasParamSpecs(BoolTypeQuery):