From 6e80e89e18da2691a86d4e2050db2e5479043b16 Mon Sep 17 00:00:00 2001
From: Evgenii Zheltonozhskii <zheltonozhskiy@gmail.com>
Date: Mon, 25 Sep 2023 17:23:50 +0300
Subject: [PATCH] Fix utils mypy errors (#8264)

---
 qiskit/utils/deprecation.py | 33 ++++++++++++++++++---------------
 qiskit/utils/units.py       |  7 +++----
 2 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/qiskit/utils/deprecation.py b/qiskit/utils/deprecation.py
index 92cd4d44b863..57fecfd9a449 100644
--- a/qiskit/utils/deprecation.py
+++ b/qiskit/utils/deprecation.py
@@ -17,13 +17,14 @@
 import functools
 import inspect
 import warnings
-from typing import Any, Callable, Dict, Optional, Type, Tuple, Union
+from collections.abc import Callable
+from typing import Any, Type
 
 
 def deprecate_func(
     *,
     since: str,
-    additional_msg: Optional[str] = None,
+    additional_msg: str | None = None,
     pending: bool = False,
     package_name: str = "qiskit-terra",
     removal_timeline: str = "no earlier than 3 months after the release date",
@@ -104,12 +105,12 @@ def deprecate_arg(
     name: str,
     *,
     since: str,
-    additional_msg: Optional[str] = None,
-    deprecation_description: Optional[str] = None,
+    additional_msg: str | None = None,
+    deprecation_description: str | None = None,
     pending: bool = False,
     package_name: str = "qiskit-terra",
-    new_alias: Optional[str] = None,
-    predicate: Optional[Callable[[Any], bool]] = None,
+    new_alias: str | None = None,
+    predicate: Callable[[Any], bool] | None = None,
     removal_timeline: str = "no earlier than 3 months after the release date",
 ):
     """Decorator to indicate an argument has been deprecated in some way.
@@ -204,10 +205,10 @@ def wrapper(*args, **kwargs):
 
 
 def deprecate_arguments(
-    kwarg_map: Dict[str, Optional[str]],
+    kwarg_map: dict[str, str | None],
     category: Type[Warning] = DeprecationWarning,
     *,
-    since: Optional[str] = None,
+    since: str | None = None,
 ):
     """Deprecated. Instead, use `@deprecate_arg`.
 
@@ -280,7 +281,7 @@ def deprecate_function(
     stacklevel: int = 2,
     category: Type[Warning] = DeprecationWarning,
     *,
-    since: Optional[str] = None,
+    since: str | None = None,
 ):
     """Deprecated. Instead, use `@deprecate_func`.
 
@@ -313,15 +314,15 @@ def wrapper(*args, **kwargs):
 
 def _maybe_warn_and_rename_kwarg(
     args: tuple[Any, ...],
-    kwargs: Dict[str, Any],
+    kwargs: dict[str, Any],
     *,
     func_name: str,
     original_func_co_varnames: tuple[str, ...],
     old_arg_name: str,
-    new_alias: Optional[str],
+    new_alias: str | None,
     warning_msg: str,
     category: Type[Warning],
-    predicate: Optional[Callable[[Any], bool]],
+    predicate: Callable[[Any], bool] | None,
 ) -> None:
     # In Python 3.10+, we should set `zip(strict=False)` (the default). That is, we want to
     # stop iterating once `args` is done, since some args may have not been explicitly passed as
@@ -353,9 +354,11 @@ def _write_deprecation_msg(
     pending: bool,
     additional_msg: str,
     removal_timeline: str,
-) -> Tuple[str, Union[Type[DeprecationWarning], Type[PendingDeprecationWarning]]]:
+) -> tuple[str, Type[DeprecationWarning] | Type[PendingDeprecationWarning]]:
     if pending:
-        category = PendingDeprecationWarning
+        category: Type[DeprecationWarning] | Type[
+            PendingDeprecationWarning
+        ] = PendingDeprecationWarning
         deprecation_status = "pending deprecation"
         removal_desc = f"marked deprecated in a future release, and then removed {removal_timeline}"
     else:
@@ -412,7 +415,7 @@ def _write_deprecation_msg(
 
 
 def add_deprecation_to_docstring(
-    func: Callable, msg: str, *, since: Optional[str], pending: bool
+    func: Callable, msg: str, *, since: str | None, pending: bool
 ) -> None:
     """Dynamically insert the deprecation message into ``func``'s docstring.
 
diff --git a/qiskit/utils/units.py b/qiskit/utils/units.py
index 76f300805c6c..76bd9ff77145 100644
--- a/qiskit/utils/units.py
+++ b/qiskit/utils/units.py
@@ -11,15 +11,14 @@
 # that they have been altered from the originals.
 
 """SI unit utilities"""
-
-from typing import Tuple, Optional, Union
+from __future__ import annotations
 
 import numpy as np
 
 from qiskit.circuit.parameterexpression import ParameterExpression
 
 
-def apply_prefix(value: Union[float, ParameterExpression], unit: str) -> float:
+def apply_prefix(value: float | ParameterExpression, unit: str) -> float | ParameterExpression:
     """
     Given a SI unit prefix and value, apply the prefix to convert to
     standard SI unit.
@@ -69,7 +68,7 @@ def apply_prefix(value: Union[float, ParameterExpression], unit: str) -> float:
     return value * pow(10, pow10)
 
 
-def detach_prefix(value: float, decimal: Optional[int] = None) -> Tuple[float, str]:
+def detach_prefix(value: float, decimal: int | None = None) -> tuple[float, str]:
     """
     Given a SI unit value, find the most suitable prefix to scale the value.