From 09e8fa96c7bf821916e9a21135359d1507fa5b68 Mon Sep 17 00:00:00 2001
From: Jon Dufresne <jon.dufresne@gmail.com>
Date: Mon, 14 Dec 2020 14:24:42 -0800
Subject: [PATCH] Distribute and install py.typed to provide type information

Complies with PEP 561:
https://www.python.org/dev/peps/pep-0561/#packaging-type-information

By distributing and installing the py.typed file, mypy will use pip's
type information when imported into other projects. For example, the
pip-tools project can use pip's types and mypy to help verify
correctness.

mypy docs:
https://mypy.readthedocs.io/en/stable/installed_packages.html#making-pep-561-compatible-packages
---
 setup.py         | 1 +
 src/pip/py.typed | 4 ++++
 2 files changed, 5 insertions(+)
 create mode 100644 src/pip/py.typed

diff --git a/setup.py b/setup.py
index 2601d8bd912..3c0d08c3c63 100644
--- a/setup.py
+++ b/setup.py
@@ -68,6 +68,7 @@ def get_version(rel_path):
         exclude=["contrib", "docs", "tests*", "tasks"],
     ),
     package_data={
+        "pip": ["py.typed"],
         "pip._vendor": ["vendor.txt"],
         "pip._vendor.certifi": ["*.pem"],
         "pip._vendor.requests": ["*.pem"],
diff --git a/src/pip/py.typed b/src/pip/py.typed
new file mode 100644
index 00000000000..0b44fd9b5c7
--- /dev/null
+++ b/src/pip/py.typed
@@ -0,0 +1,4 @@
+pip is a command line program. While it is implemented in Python, and so is
+available for import, you must not use pip's internal APIs in this way. Typing
+information is provided as a convenience only and is not a gaurantee. Expect
+unannounced changes to the API and types in releases.