ast: update for py38 (#3698)

stdlib/3/_ast.pyi

@@ -251,12 +251,6 @@ class Call(expr):
     args: typing.List[expr]
     keywords: typing.List[keyword]
 
-class Num(expr):  # Deprecated in 3.8; use Constant
-    n: complex
-
-class Str(expr):  # Deprecated in 3.8; use Constant
-    s: str
-
 if sys.version_info >= (3, 6):
     class FormattedValue(expr):
         value: expr
@@ -266,11 +260,20 @@ if sys.version_info >= (3, 6):
     class JoinedStr(expr):
         values: typing.List[expr]
 
-class Bytes(expr):  # Deprecated in 3.8; use Constant
-    s: bytes
+if sys.version_info < (3, 8):
+    class Num(expr):  # Deprecated in 3.8; use Constant
+        n: complex
 
-class NameConstant(expr):
-    value: Any
+    class Str(expr):  # Deprecated in 3.8; use Constant
+        s: str
+
+    class Bytes(expr):  # Deprecated in 3.8; use Constant
+        s: bytes
+
+    class NameConstant(expr):  # Deprecated in 3.8; use Constant
+        value: Any
+
+    class Ellipsis(expr): ...  # Deprecated in 3.8; use Constant
 
 if sys.version_info >= (3, 6):
     class Constant(expr):
@@ -285,8 +288,6 @@ if sys.version_info >= (3, 8):
         target: expr
         value: expr
 
-class Ellipsis(expr): ...
-
 class Attribute(expr):
     value: expr
     attr: _identifier

stdlib/3/ast.pyi

@@ -65,3 +65,10 @@ def literal_eval(node_or_string: Union[str, AST]) -> Any: ...
 if sys.version_info >= (3, 8):
     def get_source_segment(source: str, node: AST, *, padded: bool = ...) -> Optional[str]: ...
 def walk(node: AST) -> Iterator[AST]: ...
+
+if sys.version_info >= (3, 8):
+    class Num(Constant): ...
+    class Str(Constant): ...
+    class Bytes(Constant): ...
+    class NameConstant(Constant): ...
+    class Ellipsis(Constant): ...