Subject: Re: [PATCH v3 4/4] cache-tree: do not generate empty trees as a result of all i-t-a subentries

From: Junio C Hamano <[email-masked]>
Date: Tue, 12 Jul 2016 13:49:18 -0700

Nguyễn Thái Ngọc Duy  <[email-masked]> writes:

> diff --git a/cache-tree.c b/cache-tree.c
> index c2676e8..2d50640 100644
> --- a/cache-tree.c
> +++ b/cache-tree.c
> @@ -380,6 +380,13 @@ static int update_one(struct cache_tree *it,
>  			continue;
>  		}
>  
> +		/*
> +		 * "sub" can be an empty tree if subentries are i-t-a.
> +		 */
> +		if (sub && sub->cache_tree->entry_count < 0 &&
> +		    !hashcmp(sha1, EMPTY_TREE_SHA1_BIN))
> +			continue;
> +

Looks sensible, except that it is unclear if it is correct to assume
that "subentries are ita" always equals to "entry_count < 0" here.
I _think_ it is OK, as the function itself does use the latter as
the sign that it hit to_invalidate=1 case when it returns.

Thanks.

>  		strbuf_grow(&buffer, entlen + 100);
>  		strbuf_addf(&buffer, "%o %.*s%c", mode, entlen, path + baselen, '\0');
>  		strbuf_add(&buffer, sha1, 20);
> diff --git a/t/t2203-add-intent.sh b/t/t2203-add-intent.sh
> index 24aed2e..f4b2fac 100755
> --- a/t/t2203-add-intent.sh
> +++ b/t/t2203-add-intent.sh
> @@ -99,5 +99,19 @@ test_expect_success 'cache-tree does not ignore dir that has i-t-a entries' '
>  	)
>  '
>  
> +test_expect_success 'cache-tree does skip dir that becomes empty' '
> +	rm -fr ita-in-dir &&
> +	git init ita-in-dir &&
> +	(
> +		cd ita-in-dir &&
> +		mkdir -p 1/2/3 &&
> +		echo 4 >1/2/3/4 &&
> +		git add -N 1/2/3/4 &&
> +		git write-tree >actual &&
> +		echo $_EMPTY_TREE >expected &&
> +		test_cmp expected actual
> +	)
> +'
> +
>  test_done