Re: [PATCH 2/2] add -i: default to the built-in implementation

> From: Johannes Schindelin <johannes.schindelin@gmx.de>
>
> In 9a5315edfdf (Merge branch 'js/patch-mode-in-others-in-c',
> 2020-02-05), Git acquired a built-in implementation of `git add`'s
> interactive mode that could be turned on via the config option
> `add.interactive.useBuiltin`.
>
> The first official Git version to support this knob was v2.26.0.
>
> In 2df2d81ddd0 (add -i: use the built-in version when
> feature.experimental is set, 2020-09-08), this built-in implementation
> was also enabled via `feature.experimental`. The first version with this
> change was v2.29.0.
>
> More than a year (and very few bug reports) later, it is time to declare
> the built-in implementation mature and to turn it on by default.
>
> We specifically leave the `add.interactive.useBuiltin` configuration in
> place, to give users an "escape hatch" in the unexpected case should
> they encounter a previously undetected bug in that implementation.
>
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>  Documentation/config/add.txt |  6 +++---
>  builtin/add.c                | 15 +++++----------
>  ci/run-build-and-tests.sh    |  2 +-
>  t/README                     |  2 +-
>  t/t2016-checkout-patch.sh    |  2 +-
>  5 files changed, 11 insertions(+), 16 deletions(-)
>
> diff --git a/Documentation/config/add.txt b/Documentation/config/add.txt
> index c9f748f81cb..3e859f34197 100644
> --- a/Documentation/config/add.txt
> +++ b/Documentation/config/add.txt
> @@ -7,6 +7,6 @@ add.ignore-errors (deprecated)::
>  	variables.
>  
>  add.interactive.useBuiltin::
> -	[EXPERIMENTAL] Set to `true` to use the experimental built-in
> -	implementation of the interactive version of linkgit:git-add[1]
> -	instead of the Perl script version. Is `false` by default.
> +	Set to `false` to fall back to the original Perl implementation of
> +	the interactive version of linkgit:git-add[1] instead of the built-in
> +	version. Is `true` by default.

> diff --git a/builtin/add.c b/builtin/add.c
> index ef6b619c45e..8ef230a345b 100644
> --- a/builtin/add.c
> +++ b/builtin/add.c
> @@ -237,17 +237,12 @@ int run_add_interactive(const char *revision, const char *patch_mode,
>  	int use_builtin_add_i =
>  		git_env_bool("GIT_TEST_ADD_I_USE_BUILTIN", -1);
>  
> -	if (use_builtin_add_i < 0) {
> -		int experimental;
> -		if (!git_config_get_bool("add.interactive.usebuiltin",
> -					 &use_builtin_add_i))
> -			; /* ok */
> -		else if (!git_config_get_bool("feature.experimental", &experimental) &&
> -			 experimental)
> -			use_builtin_add_i = 1;
> -	}
> +	if (use_builtin_add_i < 0 &&
> +	    git_config_get_bool("add.interactive.usebuiltin",
> +				&use_builtin_add_i))
> +		use_builtin_add_i = 1;
>  
> -	if (use_builtin_add_i == 1) {
> +	if (use_builtin_add_i != 0) {