chore: use --since in release_notes.py (#6915)

The semantics of `release_notes.py` was slightly confusing. It is meant
to be run a `script/release_notes.py v4.15.0` on the `releases/v4.16.0`
branch. To help, I've changed the usage to `script/release_notes.py
--since v4.15.0`.

doc/dev/release_checklist.md

@@ -102,7 +102,7 @@ We'll use `v4.6.0` as the intended release version as a running example.
       - Toolchain bump PR including updated Lake manifest
       - Create and push the tag
       - Merge the tag into `stable`
-- Run `scripts/release_checklist.py v4.6.0` to check that everything is in order.
+- Run `script/release_checklist.py v4.6.0` to check that everything is in order.
 - The `v4.6.0` section of `RELEASES.md` is out of sync between
   `releases/v4.6.0` and `master`. This should be reconciled:
   - Replace the `v4.6.0` section on `master` with the `v4.6.0` section on `releases/v4.6.0`
@@ -252,8 +252,10 @@ Please read https://leanprover-community.github.io/contribute/tags_and_branches.
 
 Release notes are automatically generated from the commit history, using `script/release_notes.py`.
 
-Run this as `script/release_notes.py v4.6.0`, where `v4.6.0` is the *previous* release version. This will generate output
-for all commits since that tag. Note that there is output on both stderr, which should be manually reviewed,
+Run this as `script/release_notes.py --since v4.6.0`, where `v4.6.0` is the *previous* release version.
+This script should be run on the `releases/v4.7.0` branch.
+This will generate output for all commits since that tag.
+Note that there is output on both stderr, which should be manually reviewed,
 and on stdout, which should be manually copied to `RELEASES.md`.
 
 There can also be pre-written entries in `./releases_drafts`, which should be all incorporated in the release notes and then deleted from the branch.

script/release_checklist.py

@@ -185,7 +185,7 @@ def main():
             previous_minor_version = version_minor - 1
             previous_stable_branch = f"releases/v{version_major}.{previous_minor_version}.0"
             previous_release = f"v{version_major}.{previous_minor_version}.0"
-            print(f"  ❌ Release notes not published. Please run `script/release_notes.py {previous_release}` on branch `{previous_stable_branch}`.")
+            print(f"  ❌ Release notes not published. Please run `script/release_notes.py --since {previous_release}` on branch `{branch_name}`.")
     else:
         print(f"  ❌ Release page for {toolchain} does not exist")
 

script/release_notes.py

@@ -5,6 +5,7 @@ import re
 import json
 import requests
 import subprocess
+import argparse
 from collections import defaultdict
 from git import Repo
 
@@ -65,20 +66,19 @@ def format_markdown_description(pr_number, description):
     return f"{link} {description}"
 
 def main():
-    if len(sys.argv) != 2:
-        sys.stderr.write("Usage: script.py <git-tag>\n")
-        sys.exit(1)
+    parser = argparse.ArgumentParser(description='Generate release notes from Git commits')
+    parser.add_argument('--since', required=True, help='Git tag to generate release notes since')
+    args = parser.parse_args()
 
-    tag = sys.argv[1]
     try:
         repo = Repo(".")
     except Exception as e:
         sys.stderr.write(f"Error opening Git repository: {e}\n")
         sys.exit(1)
 
-    commits = get_commits_since_tag(repo, tag)
+    commits = get_commits_since_tag(repo, args.since)
 
-    sys.stderr.write(f"Found {len(commits)} commits since tag {tag}:\n")
+    sys.stderr.write(f"Found {len(commits)} commits since tag {args.since}:\n")
     for commit_hash, first_line, _ in commits:
         sys.stderr.write(f"- {commit_hash}: {first_line}\n")