Feature request: Add commit reference to changelog

[scoopex]

When squashing commits before merging them to the integration branch, the commithash of the change and its changelog are identical.
It would be very helpful to use this information to generate a link to the sourcecode change (in the same way like towncrier does that for issues).

When creating a changelog with --commit this information can be added as an link to the sourcecode management system as an extra information after the issue link.

[adiroiban]

Hi Marc

Thanks for the report.

I am not sure I understand the feature request here/requiremets/specification.

Can you please provide an example with the following info

• when do you expect to call towncrier CLI,
• the command line arguments and the state of the repo / news fragment files
• the expected output

If you have time, it would help to draft the documentation for such a feature.
When the feature is implemented we can reuse the documentation.

Cheers

[scoopex]

Sure :-)

1. Step: Create a branch
2. Step: Create a newsfragment and add issue and changelog by towncrier create
3. Merge the change and add the change by a single commit using a squash (so newsfrgment and feature are combined in a single commit)
4. Create the changelog

   towncrier build --version 1.2.3  --commit
   

The last iterates over all newsfragments and gathers the git-commit-id of these fragments by using git log -1 --pretty=format:"%H" -- <filename> and creates a bullet which looks like this:

- When used with an :file:`pyproject.toml` file, when no explicit values are
  defined for ``[tool.towncrier.name|package]`` they will now fallback to
  the value of ``[project.name]``. (`#687 <https://github.com/twisted/towncrier/issues/687>`, @<https://github.com/tmbo/questionary/commit/dc46610910409c18f53aabbbec111221fccf8a6a>)

[adiroiban]

Thanks. Make sense.

We can update the data that we send to the Jinja rendering process.

Not all projects use squash during the merge into the main branch... so this should be optional.
But we can alwasy gather the commit ID in which the newsfragment was created... it might not always hold a "usable" information... but we can have it there, and you can optionally use it for your custom Jinja2 template.

We can also have this enabled in the default template... with a configutation option to turn it on/off

I am happy to review and approve a PR that implement this functionality.

As with any changes approved by the towncrier project, the changes will need to have documentation and tests.

Cheers

[webknjaz]

Not exactly the same but somewhat related to referencing commits (without squashing).
Personally, I make sure that changes and the change note are in diffefent commits. Then, I can use said commit hashes in file names. And finally, the ref ends up being classified in jinja: https://github.com/jazzband/pip-tools/blob/21c9b84199f777f589d9c5b190a1ee1a3d2d565f/changelog.d/.towncrier_template.md.jinja#L19-L58