Re: [PATCH v2] tree-walk.c: fix overoptimistic inclusion in :(exclude) matching

[Junio C Hamano <gitster@pobox.com>]

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

> tree_entry_interesting() is used for matching pathspec on a tree. The
> interesting thing about this function is that, because the tree
> entries are known to be sorted, this function can return more than
> just "yes, matched" and "no, not matched". It can also say "yes, this
> entry is matched and so is the remaining entries in the tree".
>
> This is where I made a mistake when matching exclude pathspec. For
> exclude pathspec, we do matching twice, one with positive patterns and
> one with negative ones, then a rule table is applied to determine the
> final "include or exclude" result. Note that "matched" does not
> necessarily mean include. For negative patterns, "matched" means
> exclude.
>
> This particular rule is too eager to include everything. Rule 8 says
> that "if all entries are positively matched" and the current entry is
> not negatively matched (i.e. not excluded), then all entries are
> positively matched and therefore included. But this is not true. If
> the _current_ entry is not negatively matched, it does not mean the
> next one will not be and we cannot conclude right away that all
> remaining entries are positively matched and can be included.
>
> Rules 8 and 18 are now updated to be less eager. We conclude that the
> current entry is positively matched and included. But we say nothing
> about remaining entries. tree_entry_interesting() will be called again
> for those entries where we will determine entries individually.

Thanks.  Will queue.

> Reported-by: Christophe Bliard <christophe.bliard@trux.info>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  v2 fixes the too broad "git add ." in the test
>
>  t/t6132-pathspec-exclude.sh | 17 +++++++++++++++++
>  tree-walk.c                 | 11 ++++++++---
>  2 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/t/t6132-pathspec-exclude.sh b/t/t6132-pathspec-exclude.sh
> index eb829fce97..2462b19ddd 100755
> --- a/t/t6132-pathspec-exclude.sh
> +++ b/t/t6132-pathspec-exclude.sh
> @@ -194,4 +194,21 @@ test_expect_success 'multiple exclusions' '
>  	test_cmp expect actual
>  '
>  
> +test_expect_success 't_e_i() exclude case #8' '
> +	git init case8 &&
> +	(
> +		cd case8 &&
> +		echo file >file1 &&
> +		echo file >file2 &&
> +		git add file1 file2 &&
> +		git commit -m twofiles &&
> +		git grep -l file HEAD :^file2 >actual &&
> +		echo HEAD:file1 >expected &&
> +		test_cmp expected actual &&
> +		git grep -l file HEAD :^file1 >actual &&
> +		echo HEAD:file2 >expected &&
> +		test_cmp expected actual
> +	)
> +'
> +
>  test_done
> diff --git a/tree-walk.c b/tree-walk.c
> index 77b37f36fa..79bafbd1a2 100644
> --- a/tree-walk.c
> +++ b/tree-walk.c
> @@ -1107,7 +1107,7 @@ enum interesting tree_entry_interesting(const struct name_entry *entry,
>  	 *   5  |  file |    1     |    1     |   0
>  	 *   6  |  file |    1     |    2     |   0
>  	 *   7  |  file |    2     |   -1     |   2
> -	 *   8  |  file |    2     |    0     |   2
> +	 *   8  |  file |    2     |    0     |   1
>  	 *   9  |  file |    2     |    1     |   0
>  	 *  10  |  file |    2     |    2     |  -1
>  	 * -----+-------+----------+----------+-------
> @@ -1118,7 +1118,7 @@ enum interesting tree_entry_interesting(const struct name_entry *entry,
>  	 *  15  |  dir  |    1     |    1     |   1 (*)
>  	 *  16  |  dir  |    1     |    2     |   0
>  	 *  17  |  dir  |    2     |   -1     |   2
> -	 *  18  |  dir  |    2     |    0     |   2
> +	 *  18  |  dir  |    2     |    0     |   1
>  	 *  19  |  dir  |    2     |    1     |   1 (*)
>  	 *  20  |  dir  |    2     |    2     |  -1
>  	 *
> @@ -1134,7 +1134,12 @@ enum interesting tree_entry_interesting(const struct name_entry *entry,
>  
>  	negative = do_match(entry, base, base_offset, ps, 1);
>  
> -	/* #3, #4, #7, #8, #13, #14, #17, #18 */
> +	/* #8, #18 */
> +	if (positive == all_entries_interesting &&
> +	    negative == entry_not_interesting)
> +		return entry_interesting;
> +
> +	/* #3, #4, #7, #13, #14, #17 */
>  	if (negative <= entry_not_interesting)
>  		return positive;