Re: [PATCH] diff --no-index: fix -R with stdin

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

On 09/09/2023 23:12, René Scharfe wrote:
> When -R is given, queue_diff() swaps the mode and name variables of the
> two files to produce a reverse diff.  1e3f26542a (diff --no-index:
> support reading from named pipes, 2023-07-05) added variables that
> indicate whether files are special, i.e named pipes or - for stdin.
> These new variables were not swapped, though, which broke the handling
> of stdin with with -R.  Swap them like the other metadata variables.
> 
> Reported-by: Martin Storsjö <martin@martin.st>
> Signed-off-by: René Scharfe <l.s.r@web.de>
> ---
> Great bug report, thank you!

Yes thank you Martin for reporting this and thank you to René for fixing 
it - I saw the report just before I went to bed and it was already fixed 
by the time I got up! The patch looks good and thanks for adding a test.

Best Wishes

Phillip

>   diff-no-index.c          |  1 +
>   t/t4053-diff-no-index.sh | 19 +++++++++++++++++++
>   2 files changed, 20 insertions(+)
> 
> diff --git a/diff-no-index.c b/diff-no-index.c
> index 8aead3e332..e7041b89e3 100644
> --- a/diff-no-index.c
> +++ b/diff-no-index.c
> @@ -232,6 +232,7 @@ static int queue_diff(struct diff_options *o,
>   		if (o->flags.reverse_diff) {
>   			SWAP(mode1, mode2);
>   			SWAP(name1, name2);
> +			SWAP(special1, special2);
>   		}
> 
>   		d1 = noindex_filespec(name1, mode1, special1);
> diff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh
> index 6781cc9078..5f059f65fc 100755
> --- a/t/t4053-diff-no-index.sh
> +++ b/t/t4053-diff-no-index.sh
> @@ -224,6 +224,25 @@ test_expect_success "diff --no-index treats '-' as stdin" '
>   	test_must_be_empty actual
>   '
> 
> +test_expect_success "diff --no-index -R treats '-' as stdin" '
> +	cat >expect <<-EOF &&
> +	diff --git b/a/1 a/-
> +	index $(git hash-object --stdin <a/1)..$ZERO_OID 100644
> +	--- b/a/1
> +	+++ a/-
> +	@@ -1 +1 @@
> +	-1
> +	+x
> +	EOF
> +
> +	test_write_lines x | test_expect_code 1 \
> +		git -c core.abbrev=no diff --no-index -R -- - a/1 >actual &&
> +	test_cmp expect actual &&
> +
> +	test_write_lines 1 | git diff --no-index -R -- a/1 - >actual &&
> +	test_must_be_empty actual
> +'
> +
>   test_expect_success 'diff --no-index refuses to diff stdin and a directory' '
>   	test_must_fail git diff --no-index -- - a </dev/null 2>err &&
>   	grep "fatal: cannot compare stdin to a directory" err
> --
> 2.42.0