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| -rw-r--r-- | README.md | 60 | ||||
| -rwxr-xr-x | bin/git-fixup | 17 | ||||
| -rw-r--r-- | setup.cfg | 2 |
3 files changed, 79 insertions, 0 deletions
@@ -95,6 +95,66 @@ to reflect the code changes in commit A. (Although of course it's usually best practice to logically group such changes together in a single commit.) But this should not stop it from being useful. +### Use case 4: automatic squashing of fixup commits + +It is often desirable to amend an existing commit which is in the +current branch but not at its head. This can be done by creating a +new commit which amends (only) the existing commit, and then use `git +rebase --interactive` in order to squash the two commits together into +a new one which reuses the commit message from the original. +`git-commit[1]` has a nice feature which makes this process convenient +even when the commit to be amended is not at the head of the current +branch. It is described in [the `git-commit[1]` man +page](https://git-scm.com/docs/git-commit): + +> `--fixup=<commit>` +> +> Construct a commit message for use with `rebase --autosquash`. The +> commit message will be the subject line from the specified commit +> with a prefix of `"fixup! "`. See `git-rebase[1]` for details. + +The corresponding details in the [`git-rebase[1]` man +page](https://git-scm.com/docs/git-rebase) are: + +> `--autosquash, --no-autosquash` +> +> When the commit log message begins with `"squash! ..."` (or `"fixup! +> ..."`), and there is already a commit in the todo list that matches +> the same ..., automatically modify the todo list of `rebase -i` so +> that the commit marked for squashing comes right after the commit to +> be modified, and change the action of the moved commit from pick to +> squash (or fixup). A commit matches the ... if the commit subject +> matches, or if the ... refers to the commit’s hash. As a fall-back, +> partial matches of the commit subject work, too. The recommended way +> to create fixup/squash commits is by using the `--fixup`/`--squash` +> options of `git-commit(1)` + +However, this process still requires manually determining which commit +should be passed to the `--fixup` option. Fortunately `git-deps` can +automate this for us. To eliminate this extra work, this repository +provides a simple script which wraps around `git-deps` to automate the +whole process. First the user should ensure that any desired +amendments to the existing commit are staged in git's index. Then +they can run the `git-fixup` script which performs the following +steps: + +1. These staged amendments to existing commit are committed using + temporary commit message. + +2. `git deps HEAD^!` is run to determine which previously existing + commit this new commit is intended to "patch". This should only + result in a single dependency, otherwise the script aborts with an + error. + +3. The temporary commit's message is amended into the correct `fixup` + form. On the next `git rebase --interactive` which includes the + original commit to be amended, `git-rebase` will automatically set + up the sequencer to apply the amendment (fixup) into the original. + +In the future, this script could be extended to optionally run the +interactive `rebase`, so that the whole amendment process is taken +care of by `git-fixup`. + ### Other uses I'm sure there are other use cases I haven't yet thought of. If you diff --git a/bin/git-fixup b/bin/git-fixup new file mode 100755 index 0000000..a79c655 --- /dev/null +++ b/bin/git-fixup @@ -0,0 +1,17 @@ +#!/bin/bash + +if ! git commit -m 'fixup commit'; then + echo >&2 "Failed to create fixup commit; aborting." + exit 1 +fi + +deps=( $( git deps HEAD^! ) ) +if [ ${#deps[@]} != 1 ]; then + echo >&2 "Failed to find a single dependency of the fixup commit; aborting." + git reset --soft HEAD^ + exit 1 +fi + +git commit --amend --fixup=$deps + +# TODO: support optionally triggering the rebase. @@ -25,6 +25,8 @@ console_scripts = gitfile-handler = git_deps.handler:run [files] +scripts = + bin/git-fixup packages = git_deps data_files = |