Re: Bash tab completion for _git_fetch alias is broken on Git 1.7.7.1

Hi,

 
[Please don't top-post.]

On Thu, Nov 10, 2011 at 3:09 PM, Johannes Sixt [off-list ref] wrote:

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Am 11/10/2011 4:21, schrieb Junio C Hamano:

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Nathan Broadbent [off-list ref] writes:

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Dear git mailing list,

I'm assigning the `_git_fetch` bash tab completion to the alias `gf`,
with the following command:

    complete -o default -o nospace -F _git_fetch gf

I assume you have an

  alias gf="git fetch"

somewhere, right?

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The tab completion then works fine in git 1.7.0.4, but breaks on git
1.7.7.1, with the following error:

I didn't actually tried, but I guess this is a side-effect of da4902a7
(completion: remove unnecessary _get_comp_words_by_ref() invocations,
2011-04-28), which was in v1.7.6.  Since the clean-up in that commit
we only call _get_comp_words_by_ref() in the top-level completion
functions _git() and _gitk() to populate completion-related variables
($cur, $prev, $words, $cword), so invoking any _git_<cmd>() completion
function directly causes an error or wrong behavior, because all those
variables are empty.

Calling a completion function directly was not an issue earlier,
because every _git_<cmd>() completion function invoked
_get_comp_words_by_ref() to populate those variables, or in the
pre-_get_comp_words_by_ref() times they just accessed the
completion-related bash variables $COMP_WORDS and $COMP_CWORD
directly.


On Thu, Nov 10, 2011 at 04:52:33PM +0800, Nathan Broadbent wrote:

So, this is a feature, not a bug... Tab completion for aliases is
really useful. It's important enough to me that I won't stop until
I've found a solution.
I can appreciate that _git_fetch is not currently meant to be called
directly, but we found a way to utilize it when it previously worked.
Perhaps the scope of these completion functions could be expanded to
allow for aliases? I'll attempt to submit a patch if someone can give
me approval.

The quickest way would be to just revert da4902a7, but it would be the
dirtiest, too: it would bring back a lot of redundant calls to
_get_comp_words_by_ref() and it might have side-effects under zsh (but
I didn't think this through).

It would be a bit more clever to revert only parts of da4902a7, i.e.
to bring back _get_comp_words_by_ref() calls in _git_<cmd> completion
functions but not in __git_<whatever>() helper functions.  This way
_git_<cmd>() functions would have their completion-related variables
initialized even when called directly instead through _git(), and
_get_comp_words_by_ref() would be called "only" twice during a single
completion.  But that's still one too many, and again: there can be
issues with zsh.

Alternatively, you could easily create your own wrapper function
around _git_fetch(), like this:

_gf () {
	local cur prev words cword
	_get_comp_words_by_ref -n =: cur prev words cword
	_git_fetch
}


However.

Having said all that, I'd like to point out that even if _git_fetch()
didn't error out when called for the 'gf' alias, it still wouldn't
work properly.  After 'gf origin <TAB>' it offers the list of remotes
again and it never offers refspecs, because it calls
__git_complete_remote_or_refspec(), which

 - depends on the fact that there must be at least two words ('git'
   and 'fetch') on the command line before the remote, and

 - needs to know the git command (i.e. fetch, pull, or push) to offer
   the proper refspecs, but it can't find that out from your alias.


Best,
Gábor