Replace ast.NameConstant with ast.Constant and remove duplicates (#2188)

This pull request includes several changes to the
`onnxscript/converter.py` and `onnxscript/converter_test.py` files to
improve compatibility with different Python versions and simplify the
code. The most important changes include removing deprecated AST node
types and updating test cases to reflect these changes.

Author: justinchuby

onnxscript/_internal/ast_utils.py

@@ -6,12 +6,9 @@
 
 import ast
 import inspect
-import sys
 import textwrap
 from typing import Callable
 
-PY_VERSION_GE_39 = sys.version_info >= (3, 9)
-
 
 def get_src_and_ast(func: Callable, /) -> tuple[str, ast.FunctionDef]:
     try:
@@ -35,17 +32,10 @@ def normalize_subscript_expr(expr: ast.Subscript):
     # Returns a list of expressions, denoting the indices, after stripping the extraneous "Index"
     # wrapper present in python versions before 3.9
     index_expr = expr.slice
-    if PY_VERSION_GE_39:
-        if isinstance(index_expr, ast.Tuple):
-            return index_expr.elts  # multiple indices
-        else:
-            return [index_expr]  # single index
+    if isinstance(index_expr, ast.Tuple):
+        return index_expr.elts  # multiple indices
     else:
-        if isinstance(index_expr, ast.ExtSlice):
-            indices = index_expr.dims  # type: ignore[attr-defined]
-        else:
-            indices = [index_expr]  # single slice-index
-        return [x.value if isinstance(x, ast.Index) else x for x in indices]  # type: ignore[attr-defined]
+        return [index_expr]  # single index
 
 
 def is_print_call(stmt: ast.stmt) -> bool:

onnxscript/converter.py

@@ -23,9 +23,6 @@
 from onnxscript import type_annotation as ta
 from onnxscript._internal import analysis, ast_utils, autocast, param_manipulation
 
-PY_VERSION_GE_39 = ast_utils.PY_VERSION_GE_39
-
-
 logger = logging.getLogger("onnxscript")
 
 
@@ -435,14 +432,10 @@ def _is_constant_expr(self, node: ast.AST) -> None:
                 ast.BinOp,
                 ast.UnaryOp,
                 ast.Compare,
-                ast.Num,
-                ast.Str,
                 ast.Attribute,
                 ast.List,
                 ast.Load,
-                ast.NameConstant,
                 ast.Constant,
-                ast.Str,
             ),
         ):
             return all(self._is_constant_expr(c) for c in ast.iter_child_nodes(node))
@@ -578,9 +571,9 @@ def _translate_expr(
 
     def _translate_opt_expr(self, node: ast.expr) -> Optional[Variable]:
         """Translation of an expression where "None" is permitted (eg., for an optional argument).
-        None is represented as a NameConstant in Python 3.7 and Constant in Python 3.9.
+        None is represented as a Constant in Python 3.9+.
         """
-        if isinstance(node, (ast.NameConstant, ast.Constant)) and (node.value is None):
+        if isinstance(node, ast.Constant) and (node.value is None):
             return None
         return self._translate_expr(node)
 
@@ -629,7 +622,7 @@ def _translate_subscript_expr(
             target = f"{var_name}_subscripted"
         target = self.generate_unique_name(target)
         indices = ast_utils.normalize_subscript_expr(node)
-        info = self._source_of(node.slice if PY_VERSION_GE_39 else node)
+        info = self._source_of(node.slice)
 
         # Create cached int constants:
         # TODO: Do this at a graph-scope level.

onnxscript/converter_test.py

@@ -5,7 +5,6 @@
 import inspect
 import os
 import pathlib
-import sys
 import textwrap
 import types
 import typing
@@ -437,8 +436,7 @@ def f1(A: FLOAT[...]) -> FLOAT[...]:
             r = A[index]
             return r
 
-        ast_name = "_ast" if sys.version_info[:2] < (3, 9) else "ast"
-        self.check_failure(f1, f"Left term must be a tuple not '<class '{ast_name}.Name'>'")
+        self.check_failure(f1, "Left term must be a tuple not '<class 'ast.Name'>'")
 
     def check_run(self, onnxfn, inputs, expected_output):
         # Test by converting to model and running with ORT