Subject: Re: [PATCH] unpack-trees: pass checkout state explicitly to check_updates()

From: Junio C Hamano <[email-masked]>
Date: Tue, 13 Sep 2016 16:25:47 -0700

René Scharfe <[email-masked]> writes:

> Add a parameter for the struct checkout variable to check_updates()
> instead of using a static global variable.  Passing it explicitly makes
> object ownership and usage more easily apparent.  And we get rid of a
> static variable; those can be problematic in library-like code.
> ...
> diff --git a/unpack-trees.c b/unpack-trees.c
> index 11c37fb..74d6dd4 100644
> --- a/unpack-trees.c
> +++ b/unpack-trees.c
> @@ -218,8 +218,8 @@ static void unlink_entry(const struct cache_entry *ce)
>  	schedule_dir_for_removal(ce->name, ce_namelen(ce));
>  }
>  
> -static struct checkout state;

> ...
> @@ -1094,6 +1094,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
>  	int i, ret;
>  	static struct cache_entry *dfc;
>  	struct exclude_list el;
> +	struct checkout state;

Does the distinction between this thing in BSS implicitly cleared
and the new one on stack that does not seem to have any
initialization matter?

	... goes and looks ...

OK, after this hunk we clear and set up everything in state, so
there is no difference in behaviour.  Just we got rid of an
unnecessary file-scope global.

Nice.  Thanks.
  
>  	if (len > MAX_UNPACK_TREES)
>  		die("unpack_trees takes at most %d trees", MAX_UNPACK_TREES);
> @@ -1239,7 +1240,7 @@ int unpack_trees(unsigned len, struct tree_desc *t, struct unpack_trees_options
>  	}
>  
>  	o->src_index = NULL;
> -	ret = check_updates(o) ? (-2) : 0;
> +	ret = check_updates(o, &state) ? (-2) : 0;
>  	if (o->dst_index) {
>  		if (!ret) {
>  			if (!o->result.cache_tree)