Contribution Guidelines

Commit Messages

Good commit messages serve at least three important purposes:

• To speed up the reviewing process.
• To help writing good release notes.
• To help the future maintainers of CP2K (it could be you!), say five years into the future, to find out why a particular change was made to the code or why a specific feature was added.

Structure your commit message like this:

Based on: https://git-scm.com/book/ch5-2.html

short summary of changes  (50 chars or less)

More detailed explanatory text, if necessary.  Wrap it to about 72
characters or so.  In some contexts, the first line is treated as the
subject of an email and the rest of the text as the body.  The blank
line separating the summary from the body is critical (unless you omit
the body entirely); tools like rebase can get confused if you run the
two together.

Further paragraphs come after blank lines.

  - Bullet points are okay, too

  - Typically a hyphen or asterisk is used for the bullet, preceded by a
    single space, with blank lines in between, but conventions vary here

You can specify tags to resolve an issue directly when the commit
gets merged, like so:

Fixes: #45

DO

• Write the summary line and description of what you have done in the imperative mode, that is as if you were commanding someone.
• Start the line with "Fix", "Add", "Change" instead of "Fixed", "Added", "Changed".
• Possibly prefix the summary with "category: " where category can be a folder like regtesting or tests, a subsystem like xc, hfx or even a specific file like do_regtest.
• Always leave the second line blank.
• Line break the commit message (to make the commit message readable without having to scroll horizontally in gitk).
• Use the body to explain what and why vs. how

DON'T

• Don't end the summary line with a period - it's a title and titles don't end with a period.

Tips

• If it seems difficult to summarize what your commit does, it may be because it includes several logical changes or bug fixes, and are better split up into several commits using git add -p or git add -i.

References

• How to write a commit message
• On commit messages
• This entire paragraph started as a copy of Erlangs "Writing good commit messages".