Fix typevariable name generation

trans/transpiler/phases/typing/types.py

@@ -79,16 +79,21 @@ class MagicType(BaseType, typing.Generic[T]):
 
 cur_var = 0
 
+def next_var_id():
+    global cur_var
+    cur_var += 1
+    return cur_var
+
 
 @dataclass(eq=False)
 class TypeVariable(BaseType):
-    name: str = field(default_factory=lambda: chr(ord('a') + cur_var))
+    name: str = field(default_factory=lambda: next_var_id())
     resolved: Optional[BaseType] = None
 
     def __str__(self):
         if self.resolved is None:
             #return f"TypeVar[\"{self.name}\"]"
-            return "_" + self.name
+            return f"_{self.name}"
         return str(self.resolved)
 
     def resolve(self) -> BaseType: