Re: [PATCH] [GSoC][MICRO] Forbid "log --graph --no-walk"

[Eric Sunshine <sunshine@sunshineco.com>]

On Fri, Mar 6, 2015 at 3:55 AM, Dongcan Jiang <dongcan.jiang@gmail.com> wrote:
> Forbid "log --graph --no-walk

Style: drop capitalization in the Subject: line. Also prefix with the
command or module being modified, followed by a colon. So:

    log: forbid combining --graph and --no-walk

or:

    revision: forbid combining --graph and --no-walk

> Because --graph is about connected history while --no-walk is about discrete points.

Okay. You might also want to cite the wider discussion[1].

[1]: http://article.gmane.org/gmane.comp.version-control.git/216083

> revision.c: Judge whether --graph and --no-walk come together when running git-log.
> buildin/log.c: Set git-log cmd flag.
> Documentation/rev-list-options.txt: Add specification on the forbidden usage.

No need to repeat in prose what the patch itself states more clearly
and concisely.

Also, such a change should be accompanied by new test(s).

> Signed-off-by: Dongcan Jiang <dongcan.jiang@gmail.com>
> ---
> diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
> index 4ed8587..eea2c0a 100644
> --- a/Documentation/rev-list-options.txt
> +++ b/Documentation/rev-list-options.txt
> @@ -679,6 +679,7 @@ endif::git-rev-list[]
>         given on the command line. Otherwise (if `sorted` or no argument
>         was given), the commits are shown in reverse chronological order
>         by commit time.
> +       Cannot be combined with `--graph` when running git-log.
>
>  --do-walk::
>         Overrides a previous `--no-walk`.
> @@ -781,6 +782,7 @@ you would get an output like this:
>         on the left hand side of the output.  This may cause extra lines
>         to be printed in between commits, in order for the graph history
>         to be drawn properly.
> +       Cannot be combined with `--no-walk` when running git-log.

Nice to see documentation updates. More below.

>  This enables parent rewriting, see 'History Simplification' below.
>  +
> diff --git a/builtin/log.c b/builtin/log.c
> index dd8f3fc..7bf5adb 100644
> --- a/builtin/log.c
> +++ b/builtin/log.c
> @@ -627,6 +627,7 @@ int cmd_log(int argc, const char **argv, const char *prefix)
>         git_config(git_log_config, NULL);
>
>         init_revisions(&rev, prefix);
> +       rev.cmd_is_log = 1;
>         rev.always_show_header = 1;
>         memset(&opt, 0, sizeof(opt));
>         opt.def = "HEAD";
> diff --git a/revision.c b/revision.c
> index 66520c6..5f62c89 100644
> --- a/revision.c
> +++ b/revision.c
> @@ -1399,6 +1399,8 @@ void init_revisions(struct rev_info *revs, const char *prefix)
>
>         revs->commit_format = CMIT_FMT_DEFAULT;
>
> +       revs->cmd_is_log = 0;
> +
>         init_grep_defaults();
>         grep_init(&revs->grep_filter, prefix);
>         revs->grep_filter.status_only = 1;
> @@ -2339,6 +2341,8 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
>
>         if (revs->reflog_info && revs->graph)
>                 die("cannot combine --walk-reflogs with --graph");
> +       if (revs->no_walk && revs->graph && revs->cmd_is_log)

Placing 'revs->cmd_is_log' first would make it clear at a glance that
this restriction impacts 'log' only (but see question below):

    if (revs->cmd_is_log && revs->no_walk && revs->graph)

> +               die("cannot combine --no-walk with --graph when running git-log");
>         if (!revs->reflog_info && revs->grep_filter.use_reflog_filter)
>                 die("cannot use --grep-reflog without --walk-reflogs");
>
> diff --git a/revision.h b/revision.h
> index 0ea8b4e..255982a 100644
> --- a/revision.h
> +++ b/revision.h
> @@ -146,6 +146,9 @@ struct rev_info {
>                         track_first_time:1,
>                         linear:1;
>
> +       /* cmd type */
> +       unsigned int  cmd_is_log:1;

Genuine question: Despite the GSoC micro-project mentioning only
'log', is it ever meaningful for these two options to be specified
together? I suspect not, but it would be nice to hear from someone
more familiar with the issue. If not specific to 'log', then the patch
can be simplified a good deal.

>         enum date_mode date_mode;
>
>         unsigned int    abbrev;
> --