Import TypeAlias from typing_extensions where needed

EliahKagan · EliahKagan · commit c6c081230f4b · 2025-06-07T11:58:07.000-04:00
The standard library `typing` module introduced `TypeAlias` in Python 3.10. This uses it from `typing_extensions` where neederd, by making three changes: - Change the version lower bound for `typing-extensions` from 3.7.4.3 to 3.10.0.2, since 3.7.4.3 doesn't offer `TypeAlias`. (The reason not to go higher, to major version 4, is that it no longer supports versions of Python lower than 3.9, but we currently support Python 3.7 and Python 3.8.) - Require the `typing-extensions` dependency when using Python versions lower than 3.10, rather than only lower than 3.7 as before. - Conditionally import `TypeAlias` (in the `git.cmd` module) from either `typing` or `type_extensions` depending on the Python version, using a pattern that `mypy` and other type checkers recognize statically. Together with the preceding commit, this fixes #2038. (This is approach (2) described there.)
diff --git a/git/cmd.py b/git/cmd.py
@@ -55,12 +55,16 @@
     TYPE_CHECKING,
     TextIO,
     Tuple,
-    TypeAlias,
     Union,
     cast,
     overload,
 )
 
+if sys.version_info >= (3, 10):
+    from typing import TypeAlias
+else:
+    from typing_extensions import TypeAlias
+
 from git.types import Literal, PathLike, TBD
 
 if TYPE_CHECKING:
diff --git a/requirements.txt b/requirements.txt
@@ -1,2 +1,2 @@
 gitdb>=4.0.1,<5
-typing-extensions>=3.7.4.3;python_version<"3.8"
+typing-extensions>=3.10.0.2;python_version<"3.10"

Original file line number	Diff line number	Diff line change
`@@ -1,2 +1,2 @@`
`1`	`1`	`gitdb>=4.0.1,<5`
`2`		`-typing-extensions>=3.7.4.3;python_version<"3.8"`
	`2`	`+typing-extensions>=3.10.0.2;python_version<"3.10"`