Update constant_fold.py

Author: BobTheBuidler

mypy/constant_fold.py

@@ -78,36 +78,36 @@ def constant_fold_expr(expr: Expression, cur_mod_id: str) -> ConstantValue | Non
         base = constant_fold_expr(expr.base, cur_mod_id)
         if base is not None:
             index_expr = expr.index
-            if not isinstance(index_expr, SliceExpr):
-                index = constant_fold_expr(index_expr, cur_mod_id)
-                if index is not None:
-                    try:
-                        return base[index]  # type: ignore [index]
-                    except Exception:
+            if isinstance(index_expr, SliceExpr):
+                if index_expr.begin_index is None:
+                    begin_index = None
+                else:
+                    begin_index = constant_fold_expr(index_expr.begin_index, cur_mod_id)
+                    if begin_index is None:
                         return None
-
-            if index_expr.begin_index is None:
-                begin_index = None
-            else:
-                begin_index = constant_fold_expr(index_expr.begin_index, cur_mod_id)
-                if begin_index is None:
-                    return None
-            if index_expr.end_index is None:
-                end_index = None
-            else:
-                end_index = constant_fold_expr(index_expr.end_index, cur_mod_id)
-                if end_index is None:
+                if index_expr.end_index is None:
+                    end_index = None
+                else:
+                    end_index = constant_fold_expr(index_expr.end_index, cur_mod_id)
+                    if end_index is None:
+                        return None
+                if index_expr.stride is None:
+                    stride = None
+                else:
+                    stride = constant_fold_expr(index_expr.stride, cur_mod_id)
+                    if stride is None:
+                        return None
+                try:
+                    return base[begin_index:end_index:stride]
+                except Exception:
                     return None
-            if index_expr.stride is None:
-                stride = None
-            else:
-                stride = constant_fold_expr(index_expr.stride, cur_mod_id)
-                if stride is None:
+                    
+            index = constant_fold_expr(index_expr, cur_mod_id)
+            if index is not None:
+                try:
+                    return base[index]  # type: ignore [index]
+                except Exception:
                     return None
-            try:
-                return base[begin_index:end_index:stride]
-            except Exception:
-                return None
     return None