"""Generate the changelog for a mypy release."""

from __future__ import annotations

import argparse

import re

import subprocess

import sys

from dataclasses import dataclass

def find_all_release_branches() -> list[tuple[int, int]]:

result = subprocess.run(["git", "branch", "-r"], text=True, capture_output=True, check=True)

versions = []

for line in result.stdout.splitlines():

line = line.strip()

if m := re.match(r"origin/release-([0-9]+)\.([0-9]+)$", line):

major = int(m.group(1))

minor = int(m.group(2))

versions.append((major, minor))

return versions

def git_merge_base(rev1: str, rev2: str) -> str:

result = subprocess.run(

["git", "merge-base", rev1, rev2], text=True, capture_output=True, check=True

)

return result.stdout.strip()

@dataclass

class CommitInfo:

commit: str

author: str

title: str

pr_number: int | None

def normalize_author(author: str) -> str:

# Some ad-hoc rules to get more consistent author names.

if author == "AlexWaygood":

return "Alex Waygood"

elif author == "jhance":

return "Jared Hance"

return author

def git_commit_log(rev1: str, rev2: str) -> list[CommitInfo]:

result = subprocess.run(

["git", "log", "--pretty=%H\t%an\t%s", f"{rev1}..{rev2}"],

text=True,

capture_output=True,

check=True,

)

commits = []

for line in result.stdout.splitlines():

commit, author, title = line.strip().split("\t", 2)

pr_number = None

if m := re.match(r".*\(#([0-9]+)\) *$", title):

pr_number = int(m.group(1))

title = re.sub(r" *\(#[0-9]+\) *$", "", title)

author = normalize_author(author)

entry = CommitInfo(commit, author, title, pr_number)

commits.append(entry)

return commits

def filter_omitted_commits(commits: list[CommitInfo]) -> list[CommitInfo]:

result = []

for c in commits:

title = c.title

keep = True

if title.startswith("Sync typeshed"):

# Typeshed syncs aren't mentioned in release notes

keep = False

if title.startswith(

(

"Revert sum literal integer change",

"Remove use of LiteralString in builtins",

"Revert typeshed ctypes change",

)

):

# These are generated by a typeshed sync.

keep = False

if re.search(r"(bump|update).*version", title.lower()):

# Version number updates aren't mentioned

keep = False

if "pre-commit autoupdate" in title:

keep = False

if title.startswith(("Update commit hashes", "Update hashes")):

# Internal tool change

keep = False

if keep:

result.append(c)

return result

def normalize_title(title: str) -> str:

# We sometimes add a title prefix when cherry-picking commits to a

# release branch. Attempt to remove these prefixes so that we can

# match them to the corresponding master branch.

if m := re.match(r"\[release [0-9.]+\] *", title, flags=re.I):

title = title.replace(m.group(0), "")

return title

def filter_out_commits_from_old_release_branch(

new_commits: list[CommitInfo], old_commits: list[CommitInfo]

) -> list[CommitInfo]:

old_titles = {normalize_title(commit.title) for commit in old_commits}

result = []

for commit in new_commits:

drop = False

if normalize_title(commit.title) in old_titles:

drop = True

if normalize_title(f"{commit.title} (#{commit.pr_number})") in old_titles:

drop = True

if not drop:

result.append(commit)

else:

print(f'NOTE: Drop "{commit.title}", since it was in previous release branch')

return result

def find_changes_between_releases(old_branch: str, new_branch: str) -> list[CommitInfo]:

merge_base = git_merge_base(old_branch, new_branch)

print(f"Merge base: {merge_base}")

new_commits = git_commit_log(merge_base, new_branch)

old_commits = git_commit_log(merge_base, old_branch)

# Filter out some commits that won't be mentioned in release notes.

new_commits = filter_omitted_commits(new_commits)

# Filter out commits cherry-picked to old branch.

new_commits = filter_out_commits_from_old_release_branch(new_commits, old_commits)

return new_commits

def format_changelog_entry(c: CommitInfo) -> str:

"""

s = f" * {c.commit[:9]} - {c.title}"

if c.pr_number:

s += f" (#{c.pr_number})"

s += f" ({c.author})"

"""

title = c.title.removesuffix(".")

s = f" * {title} ({c.author}"

if c.pr_number:

s += f", PR [{c.pr_number}](https://github.com/python/mypy/pull/{c.pr_number})"

s += ")"

return s

def main() -> None:

parser = argparse.ArgumentParser(

description="Generate draft .md changelog for a mypy public release and print it to stdout."

)

parser.add_argument("version", help="target mypy version (form X.Y)")

parser.add_argument(

"--local", action="store_true", help="use local release branch, not origin"

)

args = parser.parse_args()

version: str = args.version

local: bool = args.local

version = version.removeprefix("v")

if not re.match(r"[0-9]+\.[0-9]+$", version):

sys.exit(f"error: Release must be of form X.Y (not {version!r})")

major, minor = (int(component) for component in version.split("."))

if not local:

print("Running 'git fetch' to fetch all release branches...")

subprocess.run(["git", "fetch"], check=True)

if minor > 0:

prev_major = major

prev_minor = minor - 1

else:

# For a x.0 release, the previous release is the most recent (x-1).y release.

all_releases = sorted(find_all_release_branches())

if (major, minor) not in all_releases:

sys.exit(f"error: Can't find release branch for {major}.{minor} at origin")

for i in reversed(range(len(all_releases))):

if all_releases[i][0] == major - 1:

prev_major, prev_minor = all_releases[i]

break

else:

sys.exit("error: Could not determine previous release")

print(f"Generating changelog for {major}.{minor}")

print(f"Previous release was {prev_major}.{prev_minor}")

if local:

new_branch = f"release-{major}.{minor}"

else:

new_branch = f"origin/release-{major}.{minor}"

old_branch = f"origin/release-{prev_major}.{prev_minor}"

changes = find_changes_between_releases(old_branch, new_branch)

print()

for c in changes:

print(format_changelog_entry(c))

if __name__ == "__main__":

main()