`blurb merge`: "No 'section' specified. You must provide one!"

[hugovk]

The short story

Error with blurb merge, with the unreleased version.

Long version

With current CPython main (commit 981d172f7f0613d30bef4a8934b361db7fcf0672), run blurb merge:

❯ blurb merge
You already have a 'Misc/NEWS' file.
[Type ok to overwrite> ok
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.12/bin/blurb", line 8, in <module>
    sys.exit(main())
             ^^^^^^
  File "/Users/hugo/github/core-workflow/blurb/blurb.py", line 1288, in main
    sys.exit(fn(*filtered_args, **kwargs))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/hugo/github/core-workflow/blurb/blurb.py", line 1067, in merge
    write_news(output, versions=versions)
  File "/Users/hugo/github/core-workflow/blurb/blurb.py", line 1099, in write_news
    blurbs.load(filenames[0])
  File "/Users/hugo/github/core-workflow/blurb/blurb.py", line 541, in load
    self.parse(text, metadata=metadata, filename=filename)
  File "/Users/hugo/github/core-workflow/blurb/blurb.py", line 531, in parse
    finish_entry()
  File "/Users/hugo/github/core-workflow/blurb/blurb.py", line 502, in finish_entry
    throw("No 'section' specified.  You must provide one!")
  File "/Users/hugo/github/core-workflow/blurb/blurb.py", line 459, in throw
    raise BlurbError(f"Error in {filename}:{line_number}:\n{s}")
blurb.BlurbError: Error in Misc/NEWS.d/3.6.2.rst:7:
No 'section' specified.  You must provide one!

The last released 1.1.0 still works.

git bisect points to a0db0d9:

a0db0d98b41ef1debf443c988c450de278932ee2 is the first bad commit
commit a0db0d98b41ef1debf443c988c450de278932ee2
Date:   Sun Jul 23 06:36:51 2023 -0700

    Improved error checking when parsing a Blurb. (#507)

    We now:
    * Check the entries in metadata in order, so we complain about
      the *first* one that has an error, which is a more familiar
      user experience.
    * Have checks for:
            * Invalid issue number
            * Invalid section
            * Empty section
            * Completely missing section

    (There is no test for "missing issue number", because it's legal
    to have a Blurb with no issue number.  "no changes" blurbs don't
    have an issue number.  But we do now reliably test that, *if* the
    issue number is specified, it *is* correctly formatted.)

 blurb/blurb.py                         | 54 +++++++++++++++++++++-------------
 blurb/tests/fail/invalid-gh-number.rst |  4 +++
 blurb/tests/fail/invalid-section.rst   |  4 +++
 blurb/tests/fail/no-gh-number.rst      |  4 +++
 blurb/tests/fail/no-section.rst        |  3 ++
 5 files changed, 49 insertions(+), 20 deletions(-)
 create mode 100644 blurb/tests/fail/invalid-gh-number.rst
 create mode 100644 blurb/tests/fail/invalid-section.rst
 create mode 100644 blurb/tests/fail/no-gh-number.rst
 create mode 100644 blurb/tests/fail/no-section.rst

Added in #507.

Whilst it's useful to check for a missing section in normal , maybe we should allow missing sections in combined Misc/NEWS.d/x.y.z.rst files?

We could skip the three problematic files:

-            if not 'section' in metadata:
+            if 'section' not in metadata and filename not in [
+                "Misc/NEWS.d/3.5.3.rst",
+                "Misc/NEWS.d/3.6.0.rst",
+                "Misc/NEWS.d/3.6.2.rst",
+            ]:
                 throw("No 'section' specified.  You must provide one!")

Or generally:

-            if not 'section' in metadata:
+            if 'section' not in metadata and filename.startswith("Misc/NEWS.d/next"):
                 throw("No 'section' specified.  You must provide one!")

[hugovk]

Alternatively, it's easier to add the missing sections to those three files, as was already done for others.

See python/cpython#114553 to fix them.