[PATCH] merge: support --strategy '?' for git-completion.bash

[PATCH] merge: support --strategy '?' for git-completion.bash

[Nguyễn Thái Ngọc Duy]

Bash completion support gets the list of available strategies with a
grep and sed trick which does not work on non-C locale since the anchor
string is translated and it does not cover custom strategies either.

Let's do it a better way and make git-merge provide all available
strategies in machine-readable form.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Another, perhaps better, option is add "git merge --list-strategies".
 It requires some code movement, so I'll try with a simpler approach
 first.

 Documentation/merge-options.txt        | 3 +++
 builtin/merge.c                        | 7 +++++++
 contrib/completion/git-completion.bash | 9 +--------
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/Documentation/merge-options.txt b/Documentation/merge-options.txt
index 3888c3ff85..cd4342844f 100644
--- a/Documentation/merge-options.txt
+++ b/Documentation/merge-options.txt
@@ -97,6 +97,9 @@ option can be used to override --squash.
 	If there is no `-s` option, a built-in list of strategies
 	is used instead ('git merge-recursive' when merging a single
 	head, 'git merge-octopus' otherwise).
++
+The special strategy '?' lists all available strategies and exits
+immediately. No merge operation is done.
 
 -X <option>::
 --strategy-option=<option>::
diff --git a/builtin/merge.c b/builtin/merge.c
index 30264cfd7c..a09d04302c 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -140,6 +140,13 @@ static struct strategy *get_strategy(const char *name)
 		}
 		exclude_cmds(&main_cmds, &not_strategies);
 	}
+	if (!strcmp(name, "?")) {
+		for (i = 0; i < main_cmds.cnt; i++)
+			puts(main_cmds.names[i]->name);
+		for (i = 0; i < other_cmds.cnt; i++)
+			puts(other_cmds.names[i]->name);
+		exit(0);
+	}
 	if (!is_in_cmdlist(&main_cmds, name) && !is_in_cmdlist(&other_cmds, name)) {
 		fprintf(stderr, _("Could not find merge strategy '%s'.\n"), name);
 		fprintf(stderr, _("Available strategies are:"));
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 3683c772c5..6d947be858 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -594,14 +594,7 @@ __git_is_configured_remote ()
 
 __git_list_merge_strategies ()
 {
-	git merge -s help 2>&1 |
-	sed -n -e '/[Aa]vailable strategies are: /,/^$/{
-		s/\.$//
-		s/.*://
-		s/^[ 	]*//
-		s/[ 	]*$//
-		p
-	}'
+	git merge --strategy '?'
 }
 
 __git_merge_strategies=
-- 
2.16.0.47.g3d9b0fac3a

Re: [PATCH] merge: support --strategy '?' for git-completion.bash

[Junio C Hamano]

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

> Bash completion support gets the list of available strategies with a
> grep and sed trick which does not work on non-C locale since the anchor
> string is translated and it does not cover custom strategies either.
>
> Let's do it a better way and make git-merge provide all available
> strategies in machine-readable form.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  Another, perhaps better, option is add "git merge --list-strategies".
>  It requires some code movement, so I'll try with a simpler approach
>  first.

If you run the probing "merge -s help" under C locale, that would
just be a one-liner, no ;-)  I.e.

> -	git merge -s help 2>&1 |
> +	LANG=C LC_ALL=C git merge -s help 2>&1 |

Not rejecting the patch, but just wondering.

Re: [PATCH] merge: support --strategy '?' for git-completion.bash

[Duy Nguyen]

On Thu, Jan 25, 2018 at 10:49:45AM -0800, Junio C Hamano wrote:
> Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:
> 
> > Bash completion support gets the list of available strategies with a
> > grep and sed trick which does not work on non-C locale since the anchor
> > string is translated and it does not cover custom strategies either.
> >
> > Let's do it a better way and make git-merge provide all available
> > strategies in machine-readable form.
> >
> > Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> > ---
> >  Another, perhaps better, option is add "git merge --list-strategies".
> >  It requires some code movement, so I'll try with a simpler approach
> >  first.
> 
> If you run the probing "merge -s help" under C locale, that would
> just be a one-liner, no ;-)  I.e.

That was my first choice but I was worried that it failed to catch
custom strategies which are preceded with a different anchor string
"Available custom strategies are:".

I didn't look carefully at those sed magic. But it looks like it
correctly handles this case too. So v2 follows below. It still feels
dirty to do this kind of text manipulation though. But that can wait.

-- 8< --
Subject: [PATCH] completion: fix completing merge strategies on non-C locales

The anchor string "Available strategies are:" is translatable so
__git_list_merge_strategies may fail to collect available strategies
from 'git merge' on non-C locales. Force C locale on this command.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 contrib/completion/git-completion.bash | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 3683c772c5..88813e9124 100644
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -594,7 +594,7 @@ __git_is_configured_remote ()
 
 __git_list_merge_strategies ()
 {
-	git merge -s help 2>&1 |
+	LANG=C LC_ALL=C git merge -s help 2>&1 |
 	sed -n -e '/[Aa]vailable strategies are: /,/^$/{
 		s/\.$//
 		s/.*://
-- 
2.16.1.196.g4f5118c359



-- 8< --

Re: [PATCH] merge: support --strategy '?' for git-completion.bash

[Junio C Hamano]

Duy Nguyen <pclouds@gmail.com> writes:

> I didn't look carefully at those sed magic. But it looks like it
> correctly handles this case too. So v2 follows below. It still feels
> dirty to do this kind of text manipulation though. But that can wait.

I do like "introduce and use helper feature to produce machine
parseable text" when it is appropriate.  But this alternative looks
more in line with the current design of completion script and can
easily be a maint material as pure bugfix for non C locale folks.

Will queue.

> -- 8< --
> Subject: [PATCH] completion: fix completing merge strategies on non-C locales
>
> The anchor string "Available strategies are:" is translatable so
> __git_list_merge_strategies may fail to collect available strategies
> from 'git merge' on non-C locales. Force C locale on this command.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---


>  contrib/completion/git-completion.bash | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
> index 3683c772c5..88813e9124 100644
> --- a/contrib/completion/git-completion.bash
> +++ b/contrib/completion/git-completion.bash
> @@ -594,7 +594,7 @@ __git_is_configured_remote ()
>  
>  __git_list_merge_strategies ()
>  {
> -	git merge -s help 2>&1 |
> +	LANG=C LC_ALL=C git merge -s help 2>&1 |
>  	sed -n -e '/[Aa]vailable strategies are: /,/^$/{
>  		s/\.$//
>  		s/.*://