counsel.el: counsel--git-grep-count-func-default submodule support

[mikecrowe]

(counsel--git-grep-count-func-default): Ask Git where the .git directory
is for the repository in the current directory.

Modern Git puts all the git directories for submodules underneath the top
level .git directory and then leaves a "git-file" in the submodule which
points back to the repository inside the top-level .git directory. This
means, that within a submodule, the .git file contains something like:

gitdir: ../../.git/modules/submodule-repo-name

counsel--git-grep-count-func-default runs "du -s .git 2>/dev/null" which is
bound to give a very small answer for just this small file.

So, let's ask Git to tell us where the real .git directory is and calculate
the size of that.

[basil-conto]

$() syntax is preferred over backticks; see https://unix.stackexchange.com/a/126928/230197.

[basil-conto]

You should also wrap the command substitution in double quotes to handle filenames with spaces in them; see the two answers linked in https://stackoverflow.com/a/37932117/3084001 for elaboration.

[basil-conto]

Another flexible way of calling git from Emacs is via vc-git-command.

Pros:

• Allows users to specify their preferred vc-git-program.

• Calls vc-git-program directly.

• Allows flexible error ignoring/handling via the OKSTATUS argument:

  if OKSTATUS is nil, that means to ignore error status, if it is
  `async', that means not to wait for termination of the
  subprocess; if it is t it means to ignore all execution errors
  

Cons:

• Requires ex- or implicitly loading vc-git.
• No other part of Counsel uses vc/vc-git.

Example:

(with-temp-buffer
  (vc-git-command t t () "rev-parse" "--git-dir")
  (buffer-substring (point-min) (1- (point-max))))

[basil-conto]

As always, I would prefer (and be more than willing to provide a PR) to call du and git as processes directly to avoid shell incompatibilities, thus freeing users to use whichever shell they like; see #1502 for precedent on this.

[abo-abo]

be more than willing to provide a PR

Please do. I think I've come around more to your point of view. I'd like to see how it looks like in code, trying to make it look as simple as we can, easily traceable back to a shell command.

[mikecrowe]

Is there any chance of merging my fix for this whilst we wait for @basil-conto's improved version? It's a pain having to patch this every time I upgrade. I've updated the commit to quote the argument and use $() rather than backticks as suggested by @basil-conto.

Thanks.

Mike.

[basil-conto]

Is there any chance of merging my fix for this

I think @abo-abo has been busy / on holiday / AFK for the past week or two, otherwise I'm sure this would have been merged. Thanks for being patient.

whilst we wait for @basil-conto's improved version?

I wouldn't call it an "improved version" so much as a larger refactor of how Counsel invokes subprocesses, so don't hold your breath. :) It's on my todo list, but it'll take a bit of design first, so I don't expect to have anything ready before the end of the month.

[abo-abo]

Merged, thanks.