Charvi Mendiratta <charvi077@xxxxxxxxx> writes:
> `git commit --fixup=amend:<commit>` will create an "amend!" commit.
> The resulting commit message subject will be "amend! ..." where
> "..." is the subject line of <commit> and the initial message
> body will be <commit>'s message. -m can be used to override the
> message body.
>
> The "amend!" commit when rebased with --autosquash will fixup the
> contents and replace the commit message of <commit> with the
> "amend!" commit's message body.
>
> Inorder to prevent rebase from creating commits with an empty
> message we refuse to create an "amend!" commit if commit message
> body is empty.
>
> Example usage:
> $ git commit --fixup=amend:HEAD
> $ git commit --fixup=amend:HEAD -m "clever commit message"
Sorry, but it is not so clear what these examples are trying to
illustrate.
The first one is to add a new commit to later amend the tip commit
(It is a bit of mystery why the user does not do a more usual "git
commit --amend" right there, though, and such a mystery may distract
readers. If the commit were not at the tip, e.g. HEAD~3, it may be
less distracting).
The second one, even with s|HEAD|HEAD~3| is even less clear.
Without the "-m", the resulting commit will have the subject that
begins with !amend but the log message body is taken from the given
commit, but with "-m", what happens? Does a single-liner 'clever
commit message' _replace_ the log message of the named commit,
resulting in an !amend commit that has no message from the original?
Or does 'clever commit message' get _appended_ the log message?
I think we can just remove the "example" from here and explain the
feature well in the end-user facing documentation.
> + if (fixup_message) {
> + /*
> + * check if ':' occurs before '^' or '@', otherwise
> + * fixup_message is a commit reference.
> + */
Isn't it that you only intend to parse:
--fixup
--fixup=amend:<any string that names a commit>
--fixup=<any string that names a commit>
and later extend it to allow keywords other than "amend"?
I can understand that you are trying to avoid getting fooled by
things like
--fixup='HEAD^{/commit message with a colon : in it}'
but why special case only ^ and @? This feels brittle (note that I
said "things like", exactly because I do not know if any string that
can name a commit must have "@" or "^" appear before ":" if it is to
have ":" in anywhere, which is what this code assumes).
Instead, you can find the first colon, check for known keywords (or
a string that consists only of alnums to accomodate for future
enhancement), and treat any garbage that happens to have a colon
without the "keyword" as fixup_commit. I.e. something along this
line...
const char alphas[] = "abcde...xyz";
size_t kwd_len;
kwd_len = strspn(fixup_message, alphas);
if (kwd_len && fixup_message[kwd_len] == ':') {
/* found keyword? */
fixup_message[kwd_len] = '\0';
if (!strcmp("amend", fixup_message)) {
... do the amend:<commit> thing ...
#if in-next-step-when-you-add-support-for-reword
} else if (!strcmp("reword", fixup_message)) {
... do the reword:<commit> thing ...
#endif
} else {
die(_("unknown --fixup=%s:<commit>",
fixup_message));
}
} else {
/* the entire fixup_message is the commit */
}
