Re: [PATCH 1/3] rebase: avoid non-function use of "return" on FreeBSD

From: Kyle J. McKay <mackyle@gmail.com>
Date: Apr 11, 2014, 23:08 UTC
Message-ID: <D3916156-0F84-4DD2-833F-64DF675325D3@gmail.com>
In-Reply-To: <vpq4n1zg4f9.fsf@anie.imag.fr>

On Apr 11, 2014, at 10:30, Matthieu Moy wrote:

Show 11 quoted lines

> "Kyle J. McKay" <mackyle@gmail.com> writes:
>
>> There are already nested functions with file inclusion between both
>> levels of nesting in git-rebase--interactive.sh and git-rebase--
>> merge.sh now, so it's not introducing anything new.
>
> OK, so it's less serious than I thought. But still, we're  
> introducing a
> function with 3 levels of nesting, split accross files, in an area  
> where
> we know that at least one shell is buggy ...

Currently in maint:

The current code in maint does this:

git-rebase.sh: top-level
   git-rebase.sh: run_specific_rebase()
     git-rebase.sh: run_specific_rebase_internal() -- contains "dot"
       git-rebase--interactive.sh: top-level (using --continue or -- 
skip)
         git-rebase--interactive.sh: do_rest
           git-rebase--interactive.sh: do_next
             git-rebase--interactive.sh: record_in_rewritten
               git-rebase--interactive.sh: flush_rewritten_pending

So I really do not see the additional level of nesting as an issue since we've already got much more than 3 levels of nesting going on now. If nesting was going to be a problem, something would have broken already. In fact, since the follow on patch removes the run_specific_rebase_internal function what we would have after the originally proposed first two patches is:

git-rebase.sh: top-level
   git-rebase.sh: run_specific_rebase() -- contains "dot"
     git-rebase--interactive.sh: top-level (using --continue or --skip)
       git-rebase--interactive.sh: git_rebase__interactive
         git-rebase--interactive.sh: do_rest
           git-rebase--interactive.sh: do_next
             git-rebase--interactive.sh: record_in_rewritten
               git-rebase--interactive.sh: flush_rewritten_pending

Which has exactly the same nesting depth albeit the "dot" has moved up one level.

Show 6 quoted lines

>>> IOW, why not move the whole run_specific_rebase_internal function to
>>> git-rebase--$type?
>>
>> So what change are you proposing exactly?
>
> Something along the lines of this:

Show 35 quoted lines

> diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
> index 6046778..5dfbf14 100644
> --- a/git-rebase--interactive.sh
> +++ b/git-rebase--interactive.sh
> @@ -820,6 +820,7 @@ add_exec_commands () {
> 	mv "$1.new" "$1"
> }
>
> +run_specific_rebase_infile() {
> case "$action" in
> continue)
> 	# do we have anything to commit?
> @@ -1055,3 +1056,4 @@ GIT_REFLOG_ACTION="$GIT_REFLOG_ACTION:  
> checkout $onto_name"
> output git checkout $onto || die_abort "could not detach HEAD"
> git update-ref ORIG_HEAD $orig_head
> do_rest
> +}
> diff --git a/git-rebase--merge.sh b/git-rebase--merge.sh
> index d84f412..907aa46 100644
> --- a/git-rebase--merge.sh
> +++ b/git-rebase--merge.sh
> @@ -99,6 +99,7 @@ finish_rb_merge () {
> 	say All done.
> }
>
> +run_specific_rebase_infile () {
> case "$action" in
> continue)
> 	read_state
> @@ -149,3 +150,4 @@ do
> done
>
> finish_rb_merge
> +}

The problem with these changes, particularly the git-rebase-- interactive.sh one is that a bunch of code is still run when the file is "dot" included. With the changes to git-rebase.sh, that code will now run regardless of the action and it will run before it would have now. So if any of the variables it sets affect the functions like read_basic_state or finish_rebase (they don't currently appear to), then there's a potential for new bugs. That initial code would not previously have run in the --abort case at all.

But, you say the tests pass with those changes, so the changes are probably okay. However, they create a potential situation where some code is added to the top of one of the git-rebase--$type.sh scripts and suddenly git rebase --abort stops working right because that code is being run when it shouldn't or the operation of read_basic_state and/or finish_rebase is adversely affected. Hopefully the rebase tests would catch any such issue right away though.

So, in light of the fact that function nesting seems to be a non-issue here, and it seems to me the originally proposed changes have much less potential to introduce breakage either now or in the future, I still prefer them.

--Kyle