Re: [PATCH] Add code to Mercurial VCS backend to show topic if there is any.

[Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>]

Manuel Jacob wrote on Sun, 07 Jun 2020 09:44 +0200:
> "Topics" is an experimental concept in Mercurial that augments the
> current branching concept (called "named branches").
> 
> For more information, see the not always up-to-date Mercurial Wiki page
> https://www.mercurial-scm.org/wiki/TopicPlan.

I assume "experimental" means "future releases of Mercurial are not
promised to be backwards compatible with the current design".

Is the .hg/topic file name and data format set in stone yet?

What if zsh 5.9 is released and then the Mercurial developers change
the design to make .hg/topic a directory, and release _that_?  Then
everyone who uses zsh 5.9 with hg will be stuck with vcs_info errors
until their distro upgrades to newer zsh.

Cheers,

Daniel

> ---
>  Functions/VCS_Info/Backends/VCS_INFO_get_data_hg | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/Functions/VCS_Info/Backends/VCS_INFO_get_data_hg b/Functions/VCS_Info/Backends/VCS_INFO_get_data_hg
> index cd5ef321d..e898f7298 100644
> --- a/Functions/VCS_Info/Backends/VCS_INFO_get_data_hg
> +++ b/Functions/VCS_Info/Backends/VCS_INFO_get_data_hg
> @@ -5,7 +5,7 @@
>  
>  setopt localoptions extendedglob NO_shwordsplit
>  
> -local hgbase bmfile branchfile rebasefile dirstatefile mqseriesfile \
> +local hgbase bmfile branchfile topicfile rebasefile dirstatefile mqseriesfile \
>      curbmfile curbm \
>      mqstatusfile mqguardsfile patchdir mergedir \
>      r_csetid r_lrev r_branch i_bmhash i_bmname \
> @@ -27,6 +27,7 @@ mergedir="${hgbase}/.hg/merge/"
>  bmfile="${hgbase}/.hg/bookmarks"
>  curbmfile="${hgbase}/.hg/bookmarks.current"
>  branchfile="${hgbase}/.hg/branch"
> +topicfile="${hgbase}/.hg/topic"
>  rebasefile="${hgbase}/.hg/rebasestate"
>  dirstatefile="${hgbase}/.hg/dirstate"
>  mqstatusfile="${patchdir}/status" # currently applied patches  
> @@ -69,6 +70,13 @@ fi
>  # If we still don't know the branch it's safe to assume default
>  [[ -n ${r_branch} ]] || r_branch="default"
>  
> +# Show topic if there is any (the UI for this experimental concept is not yet
> +# final, but for a long time the convention has been to join the branch name
> +# and the topic name by a colon)
> +if [[ -r ${topicfile} ]] ; then
> +    r_branch=${r_branch}:$(< ${topicfile})
> +fi
> +
>  # The working dir has uncommitted-changes if the revision ends with a +
>  if [[ $r_lrev[-1] == + ]] ; then
>      hgchanges=1