stash/reset/checkout -p: optionally use the add --patch backend written in pure C

[dscho]

At this stage on the journey to a fully built-in git add, we already have everything we need, including the --interactive and --patch options, as long as the add.interactive.useBuiltin setting is set to true. This config setting is kind of a feature flag that is currently turned off by default, and will be for a while, until we get confident enough that the built-in version does the job, and retire the Perl script.

However, the internal add--interactive helper is also used to back the --patch option of git stash, git reset, git checkout and git worktree.

This patch series (based on js/add-p-in-c) brings them "online".

Changes since v1:

• Renamed patch_mode_stage to patch_mode_add (and ADD_P_STAGE to ADD_P_ADD).
• Renamed the fields diff, apply and apply_check (that were inherited from the Perl script) to diff_cmd, apply_args and apply_check_args, respectively.
• Clarified the magic array size 4 of diff_cmd and friends.
• Introduced pseudo value PROMPT_MODE_MAX to make the array size of prompt_mode more obvious.
• Got rid of the unneeded = 0 initializers for is_reverse.

[dscho]

/submit

[gitgitgadget]

Submitted as pull.174.git.1576579264.gitgitgadget@gmail.com

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This patch series was integrated into pu via git@96a9bb8.

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This patch series was integrated into next via git@a767b89.

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This patch series was integrated into pu via git@fcb2543.

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This patch series was integrated into pu via git@7b1a26c.

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This patch series was integrated into pu via git@c1da1bc.

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This patch series was integrated into pu via git@01d074e.

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This patch series was integrated into pu via git@2eccd3b.

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This patch series was integrated into pu via git@74090b1.

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This patch series was integrated into pu via git@2682869.

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This patch series was integrated into pu via git@db21dfb.

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This patch series was integrated into pu via git@1be1585.

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This patch series was integrated into pu via git@12c1bc5.

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This patch series was integrated into pu via git@c67036e.

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This patch series was integrated into pu via git@92323a0.

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This patch series was integrated into pu via git@76bc47e.

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This patch series was integrated into pu via git@4bff803.

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This patch series was integrated into pu via git@c68418f.

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This patch series was integrated into next via git@36f6756.

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This patch series was integrated into pu via git@3a45b3c.

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This patch series was integrated into pu via git@9a5315e.

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This patch series was integrated into next via git@9a5315e.

[gitgitgadget]

This patch series was integrated into master via git@9a5315e.

[gitgitgadget]

Closed via 9a5315e.