Re: [GSoC][RFC] Convert mergetool to builtin

>
> Hello Christian
>
> Sorry for the late reply - the work on the interval based graph labels has
> been pretty chaotic. I am going to roll out the second version of this
> proposal soon.

> In the meantime,
>
> > [...]
> >> ### Conversion of mergetool--lib
> >>
> >> As mentioned earlier, conversion of the mergetool-related scripts has to be
> >> spread over 2-3 SoC or similar projects due to the size of scripts involved.
> >> Conversion of mergetool would set up most of the plumbing required for
> >> mergetool--lib and makes the subsequent conversion possible.
> >
> > I wonder if it would be better to convert git-mergetool--lib.sh first
> > and then git-difftool--helper.sh and git-mergetool.sh that are using
> > it.
>
> I had been agonizing over this decision while I was initially writing
> the proposal.
>
> My justifications for mergetool.sh over mergetool--lib.sh at the time were:

> >> ## Plan
> >>
> >> Similar to the conversion of difftool, I plan to create a builtin that shells
> >> out to a helper script. Once mergetool--lib is converted, we can retire the
> >> helper script and conversion would be complete.
> >
> > So you plan to create a builtin that would shell out to git-mergetool--lib.sh?
> >
> > Could you be clearer about what the conversion of difftool did and how
> > you plan to imitate that?
>
> Conversion of difftool had three patches:
>
> 1. difftool: add a skeleton for the upcoming builtin
> - Rename git-difftool.perl to git-legacy-difftool.perl
> - Create builtin/difftool.c which executes git-legacy-difftool.perl
> - Add difftool to builtin.h
> - Add "difftool.usebuiltin" configuration option
> - Modify build process
>
> 2. difftool: implement the functionality in the builtin
>
> 3. difftool: retire the legacy script
> - Remove git-legacy-difftool.perl from the build process
> - Remove outdated "NEEDWORK" comments
> - Remove perl dependency from test file
>
> Since most of the conversion was done in a single commit, it is hard to talk
> about the exact order of changes.

> Similar to this, my changes can be grouped as:
>
> 1. Create a skeleton builtin.
> 2. Implement scaffolding, implement shared functions, teach builtin to resolve
> symlink, submodule and deleted file conflicts, and others. They form the core
> functionality of mergetool.
> 3. Teach builtin to shell out for file conflict (at which we retire
> mergetool.sh)

> >> 8. Teach builtin to assign merge tool (July 10 - July 15)
> >> - Convert `get_configured_merge_tool` from mergetool--lib
> >> - Around 50 lines
> >
> > Ok, so at this point you start to convert git-mergetool--lib.sh. Where
> > is the converted code going to be? Does git-difftool--helper.sh needs
> > what you will convert?
>
> Yes. Some functions like get_configured_merge_tool, guess_merge_tool are only
> used by mergetool and can be moved to builtin/mergetool.c.

> >> 9. Teach builtin to shell out for file conflict (July 15 - July 31)
> >>  - Write a minimal mergetool--helper.sh (similar to difftool--helper.sh)
> >> - Call the helper script from the builtin
> >> - Retire the legacy script.
> >
> > Which legacy script?
>
> git-mergetool.sh was renamed to git-legacy-mergetool.sh back in first step.