Re: [PATCH 6/7] xdiff: simplify style assignments

[Phillip Wood <phillip.wood123@gmail.com>]

On 09/06/2021 20:28, Felipe Contreras wrote:

I don't find the commit message explains this change very well

> There is little value in checking that git_xmerge_style isn't 0 before
> changing it's default value.

I think the check is actually that git_xmerge_style isn't -1. Why is 
there little value in the check?

> Most of the time it isn't 0 anyway, so just assign the value directly.

Why to the times when it is zero (or -1) not matter?

> Also, add the missing constant for the default value: XDL_MERGE_STYLE_MERGE.
> 
> Additionally this change has the benefit that it gets rid of a Yoda
> condition.
> 
> No functional changes.

I think that is probably correct but it would be helpful if the commit 
message offered a bit more explanation.

Best Wishes

Phillip

> 
> Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
> ---
>   builtin/merge-file.c | 3 +--
>   ll-merge.c           | 3 +--
>   xdiff-interface.c    | 4 ++--
>   xdiff/xdiff.h        | 1 +
>   4 files changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/builtin/merge-file.c b/builtin/merge-file.c
> index a4097a596f..01951762ec 100644
> --- a/builtin/merge-file.c
> +++ b/builtin/merge-file.c
> @@ -55,8 +55,7 @@ int cmd_merge_file(int argc, const char **argv, const char *prefix)
>   	if (startup_info->have_repository) {
>   		/* Read the configuration file */
>   		git_config(git_xmerge_config, NULL);
> -		if (0 <= git_xmerge_style)
> -			xmp.style = git_xmerge_style;
> +		xmp.style = git_xmerge_style;
>   	}
>   
>   	argc = parse_options(argc, argv, prefix, options, merge_file_usage, 0);
> diff --git a/ll-merge.c b/ll-merge.c
> index 9a8a2c365c..4ce8d3f9cc 100644
> --- a/ll-merge.c
> +++ b/ll-merge.c
> @@ -124,8 +124,7 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
>   	xmp.level = XDL_MERGE_ZEALOUS;
>   	xmp.favor = opts->variant;
>   	xmp.xpp.flags = opts->xdl_opts;
> -	if (git_xmerge_style >= 0)
> -		xmp.style = git_xmerge_style;
> +	xmp.style = git_xmerge_style;
>   	if (marker_size > 0)
>   		xmp.marker_size = marker_size;
>   	xmp.ancestor = orig_name;
> diff --git a/xdiff-interface.c b/xdiff-interface.c
> index 64e2c4e301..19a030fbe2 100644
> --- a/xdiff-interface.c
> +++ b/xdiff-interface.c
> @@ -299,7 +299,7 @@ int xdiff_compare_lines(const char *l1, long s1,
>   	return xdl_recmatch(l1, s1, l2, s2, flags);
>   }
>   
> -int git_xmerge_style = -1;
> +int git_xmerge_style = XDL_MERGE_STYLE_MERGE;
>   
>   int git_xmerge_config(const char *var, const char *value, void *cb)
>   {
> @@ -309,7 +309,7 @@ int git_xmerge_config(const char *var, const char *value, void *cb)
>   		if (!strcmp(value, "diff3"))
>   			git_xmerge_style = XDL_MERGE_STYLE_DIFF3;
>   		else if (!strcmp(value, "merge"))
> -			git_xmerge_style = 0;
> +			git_xmerge_style = XDL_MERGE_STYLE_MERGE;
>   		/*
>   		 * Please update _git_checkout() in
>   		 * git-completion.bash when you add new merge config
> diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
> index 45883f5eb3..d24cd9f6ae 100644
> --- a/xdiff/xdiff.h
> +++ b/xdiff/xdiff.h
> @@ -64,6 +64,7 @@ extern "C" {
>   #define XDL_MERGE_FAVOR_UNION 3
>   
>   /* merge output styles */
> +#define XDL_MERGE_STYLE_MERGE 0
>   #define XDL_MERGE_STYLE_DIFF3 1
>   
>   typedef struct s_mmfile {
>