Cleanup fastparse (#20159)

Remove some unused code in mypy/fastparse.py.

Author: cdce8p

mypy/fastparse.py

@@ -144,9 +144,6 @@ def ast3_parse(
     )
 
 
-NamedExpr = ast3.NamedExpr
-Constant = ast3.Constant
-
 if sys.version_info >= (3, 10):
     Match = ast3.Match
     MatchValue = ast3.MatchValue
@@ -957,7 +954,7 @@ def do_func_def(
                 # for ellipsis arg
                 if (
                     len(func_type_ast.argtypes) == 1
-                    and isinstance(func_type_ast.argtypes[0], Constant)
+                    and isinstance(func_type_ast.argtypes[0], ast3.Constant)
                     and func_type_ast.argtypes[0].value is Ellipsis
                 ):
                     if n.returns:
@@ -1492,7 +1489,7 @@ def visit_Continue(self, n: ast3.Continue) -> ContinueStmt:
 
     # --- expr ---
 
-    def visit_NamedExpr(self, n: NamedExpr) -> AssignmentExpr:
+    def visit_NamedExpr(self, n: ast3.NamedExpr) -> AssignmentExpr:
         s = AssignmentExpr(self.visit(n.target), self.visit(n.value))
         return self.set_line(s, n)
 
@@ -1648,8 +1645,8 @@ def visit_Call(self, n: Call) -> CallExpr:
         )
         return self.set_line(e, n)
 
-    # Constant(object value) -- a constant, in Python 3.8.
-    def visit_Constant(self, n: Constant) -> Any:
+    # Constant(object value)
+    def visit_Constant(self, n: ast3.Constant) -> Any:
         val = n.value
         e: Any = None
         if val is None:
@@ -1773,8 +1770,6 @@ def visit_Tuple(self, n: ast3.Tuple) -> TupleExpr:
         e = TupleExpr(self.translate_expr_list(n.elts))
         return self.set_line(e, n)
 
-    # --- slice ---
-
     # Slice(expr? lower, expr? upper, expr? step)
     def visit_Slice(self, n: ast3.Slice) -> SliceExpr:
         e = SliceExpr(self.visit(n.lower), self.visit(n.upper), self.visit(n.step))
@@ -2030,9 +2025,9 @@ def translate_argument_list(self, l: Sequence[ast3.expr]) -> TypeList:
         return TypeList([self.visit(e) for e in l], line=self.line)
 
     def _extract_argument_name(self, n: ast3.expr) -> str | None:
-        if isinstance(n, Constant) and isinstance(n.value, str):
+        if isinstance(n, ast3.Constant) and isinstance(n.value, str):
             return n.value.strip()
-        elif isinstance(n, Constant) and n.value is None:
+        elif isinstance(n, ast3.Constant) and n.value is None:
             return None
         self.fail(
             message_registry.ARG_NAME_EXPECTED_STRING_LITERAL.format(type(n).__name__),
@@ -2058,7 +2053,7 @@ def visit_BinOp(self, n: ast3.BinOp) -> Type:
             uses_pep604_syntax=True,
         )
 
-    def visit_Constant(self, n: Constant) -> Type:
+    def visit_Constant(self, n: ast3.Constant) -> Type:
         val = n.value
         if val is None:
             # None is a type.
@@ -2114,16 +2109,10 @@ def numeric_type(self, value: object, n: AST) -> Type:
             numeric_value, type_name, line=self.line, column=getattr(n, "col_offset", -1)
         )
 
-    def visit_Index(self, n: ast3.Index) -> Type:
-        # cast for mypyc's benefit on Python 3.9
-        value = self.visit(cast(Any, n).value)
-        assert isinstance(value, Type)
-        return value
-
     def visit_Slice(self, n: ast3.Slice) -> Type:
         return self.invalid_type(n, note="did you mean to use ',' instead of ':' ?")
 
-    # Subscript(expr value, expr slice, expr_context ctx)  # Python 3.9 and later
+    # Subscript(expr value, expr slice, expr_context ctx)
     def visit_Subscript(self, n: ast3.Subscript) -> Type:
         empty_tuple_index = False
         if isinstance(n.slice, ast3.Tuple):